In case the path length has been set incorrectly during the installation of an LAS scintillometer, WINLAS can correct the Cn2 data.
In order to do so please use the following procedure.
After entering the relevant info in the parameters section, enter the path length setting set with the potentiometer of the LAS receiver in meters and enter the correct path length in the input field below.
Select ‘Run…’ in the WINLAS file menu.
WINLAS will now process the Scintillometer Cn2 data using a correction algorithm for the actual path length.
WINLAS corrects the path length in the following way:
Using the following equation to derive the intensity fluctuation data from the recorded Cn2 values calculated by the LAS using the incorrect path length setting.
(Wang et al., 1978)
Aperture diameter ~ 15cm
Initial path length
Variance of log intensity
The equation is re-written to yield the variance of the intensity fluctuations:
And finally re-calculate Cn2 with the correct path length:
End of FAQ.
A scintillometer measures the path weighted structure parameter of air, Cn2, using an optical transmitter and receiver.
In certain cases of relatively high Cn2 values the signal can become saturated depending on the diameter of the lens, wavelength and path length.
The so called saturation limit for Cn2 can be derived using the following formula (Ochs and Hill 1982)
Cn2 < 0.18.D5/3.L-8/3.λ2/6
the diameter of the scintillometer
[0.15m or 0.3 m]
the path length
the emitted wavelength
In the calculation tool below, you can calculate the saturation limit for the LAS and X-LAS scintillometer as a function of Path length.
Once the LAS has been installed and properly aligned the Path Length dial knob at the receiver control panel must be set for the correct distance between the transmitter and the receiver. The Path Length dial knob has 10 turns maximum with a vernier counter and a locking mechanism.
These graduations are NOT in units of distance! The precise path length must first be converted to a dial knob setting (Pot) using the following relationship for the LAS. The equations below can be used to find the correct Potentiometer setting as a function of pathlength for the LAS and X-LAS.
In addition you can use the calculation tool below to calculate the correct potentiometer setting for the (X)LAS.
The LAS and X-LAS scintillometer can be connected to the CR10x and CR1000 data loggers from Campbell Scientific.
Configuration examples for these data loggers can be viewed on this page, here:
Campbell CR10x Data Logger
A (X)LAS scintillometer can be connected to a Campbell CR10x data logger using a 2:1 voltage divider like VDIV2.1 from Campbell. The reason for this is the fact that the LAS has an output of 0..-5V and the standard input range of the CR10x is ± 2.5V.
The procedure is as follows:
Collect data using the data logger and check for normal operation of the Scintillometer data collection.
Campbell CR1000 Data logger
The connection procedure for the CR1000 is similar to the CR10x. The same connection to the terminals for differential measurement of the LAS signals can be used. However, the input range of this data logger is ± 5V so a voltage divider is not required.
A example configuration for the CR1000 in LoggerNet format can be found here: LAS_CR1000.CR1
Point measurements (alternative methods to LAS)
The LAS MkII Large Aperture Scintillometer provides continuous measurements over path lengths from 100 m up to 4.5 km. It is the only scintillometer currently available with a built-in display and control-pad. It has internal digital processing to make calculations in-situ and to store data and results. Measurements are on a comparable scale to the pixel size of satellite instruments, making LAS MkII ideal for ground-truthing applications. The LAS MkII is convenient to use due to low power consumption, integrated data logger, accurate reference time from GPS, and works reliably in cold environments.
The advantages of the LAS MkII are the following:
Yes you can, but there are a few points you have to take care with as the analogue data output has changed in format.
See appendix H of the latest manual, for details of the conversion of the analogue voltage output, UCn2. Note, the manual is written for the improved LAS MkII with GPS, so there will be differences in the hardware, and there are a couple of data formatting issues that are different (voltage ranges).
Most likely the format of your UCn2 data is incorrect for the latest version of Evation, as the software was developed to work with the LAS MkII, which has a different analogue voltage output (positive instead of negative).
For the LAS MkI, the Cn2 voltage output, UCn2, is output as -5 to 0V, where:
-5V analogue voltage output is equivalent to a Cn2 of 1 x 10^-17 [m-2/3]
0V is equivalent to 1 x 10^-12 (m^-2/3)
Cn2 (m^-2/3) = 10^(-12+ UCn2) (this applies to the LAS150, not to the LAS MkII !)
The latest version of the Evation software V2R5 and the new manual (vs1511) which explains the use of Evation, are available online, under downloads:
[The manual is now very comprehensive and covers all the recent improvements to the LAS MkII, such as the time from GPS, new firmware and processing software. It also includes clearer instructions for operation of the instrument and software, and several appendixes to cover additional information such as logging the serial or analogue output with an external logger, such as from Campbell Scientific.]
To derive fluxes of sensible heat (H) from the LAS measurements (Cn2), one needs to know the height of the LAS beam above the ground, also known as the effective height. Because the flux is almost linearly related to the height it is important to determine the effective height as accurate as possible (see Appendix F of the LAS manual). Over flat terrain it is relative easy to determine the LAS height: take the average of the height of the transmitter unit and receiver height (i.e. the height between the centre of the beam and the ground).
Over non-flat terrain it is a bit more complicated, because now we also need to consider the path-weighting function of the LAS. This weighting function reveals that the centre of the LAS path contributes more to the measured Cn2 data, than near the transmitter and receiver units. This calculation is easily done by using the effective height calculator built-in to the Evation software, which takes care of the weighting function.
Note: for very long path lengths (> 5km), such as when using the XLAS it is also important to consider the earth’s curvature (decreases the height in the centre of the path by approx. 2 m over a path length of 10 km.
More detailed information of deriving the effective height of scintillometers over complex terrain and the effect of atmospheric stability on the effective height can be found in: Hartogensis et al., Derivation of an Effective Height for Scintillometers: La Poza Experiment in Northwest Mexico, Journal of Hydrometeorology, 2003.
Yes, the LAS transmitter and receiver unit can be placed inside behind glass or Perspex windows, preferably at normal incidence to minimise light loss and refraction of the beam. However, it must be noted that windows absorb a fraction of the light beam (~8 to 25%) thereby limiting the maximum path length of the LAS or XLAS.
An error in the path length L of 1% results in an error of 3% in Cn2 (and thus H). This shows that the path length should be determined accurately.
The effective height or height of the LAS beam should be measured to 1 cm (a tape measure can be used for this).
The measurement principle of the LAS is based on the scattering of EM radiation by the turbulent atmosphere that result in fluctuations of the intensity of light. The turbulent eddies that produce these scintillations have a size of the order of the aperture diameter of the LAS (or XLAS). The figure below shows that in general these fluctuations lie mostly between 1 and 10 Hz (exact positing of the curve with respect to the x-axis is slightly dependant on the crosswind). The bandwidth of the LAS electronics is set around these fluctuations (0.1 Hz to 400 Hz). In this way electronic noise (> 400 Hz) and low frequency fluctuations related to absorption by the atmosphere (< 0.1 Hz) are removed.
Figure 1: Theoretical spectrum of a 0.15 m LAS (path length = 1 km, wind speed = 1.5 m/s).
Any type of fluctuations, e.g. caused by tower vibrations that lie within this bandwidth, in particular the ones that lie between 0.5 to 10 Hz can have significant effects on the measurements. It is therefore, strongly recommended to use stable and robust mounting platforms for the LAS units.
Yes, this is possible by logging the analogue output with a fast (500 Hz) data logger, and looking at the shift in the peak of the scintillation spectrum (the scintillation power spectrum shifts linearly along the frequency domain as a function of the crosswind). In the optical microwave sintillometer, the raw data is already logged at 500Hz, so this could be implimented. Built-in data processing to calculate the crosswind may be added in the future.
See the following publication for more information: van Dinther, D., O. K. Hartogensis, and A. F. Moene, 2013: Crosswinds from a single-aperture scintillometer using spectral techniques. J. Atmos. Oceanic Technol., 30, 3–21.
The LAS MkII includes an inbuilt data logger, but sometimes you may which to add the data to an existing meteorological station with its own data logger.
The LAS transmitter and receiver both have multiple analogue output signals, which can be measured by most standard data loggers. These signals allow the user to monitor the internal temperature as well as some raw signals to check the performance of the electronics. In most experiments these signals don’t have to be measured.
For general flux measurements two signals are important: the Cn2 signal and Demod signal. Both signals are measured at the receiver unit. The first signal, re-scaled Cn2, provides information of the turbulent intensity of the atmosphere and is used to derive the sensible heat flux (H). It’s range lies between 0 to 2.4 V for the LAS MkII (-5 and 0 Volt for the LAS150). The second signal: the demod signal is a measure of the signal strength and it’s range lies between 0 to 2 V for the LAS MkII (-2 and 0 Volt for the LAS150). The more positive (more negative for the LAS150), the more signal the receiver has. In general the signal strength depends on the distance between the transmitter and receiver and the opacity of the atmosphere.
The reason it is advised to measure the demod signal is that it can help with the interpretation of the Cn2 signal. In some cases the Cn2 can be difficult to understand, e.g. during rainy and foggy periods, while the demod signal shows clearly whether or not the receiver has a signal, or some signal is lost due to the weather.
The LAS instrument provides the structure parameter of the refractive index of air, Cn2. The latter can be considered as a parameter that describes the turbulent intensity of the atmosphere, in particularly related to the turbulent temperature fluctuations. This is way the LAS can be used to measure the sensible heat flux. However, the derivation of the sensible heat flux requires some steps. In each step additional meteorological data is required (see also processing data in the LAS manual):
Step 1: from Cn2 to CT2 requires data of:
Step 2: from CT2 to the sensible heat flux H requires data of:
Step 3: from H to evaporation requires data of:
In additional the gravitational acceleration, surface roughness and sensor heights are required.
It is recommended to have the additional data at the same measurement interval as the LAS data.
Step 4: selection of unstable or stable solution H:
For land surface the typical diurnal course of H shows positive values during the day and negative values at night. Explanation: during (sunny) daytime conditions (roughly between sun rise and sun set) the earth’s surface heats up the atmosphere from below. This means H is pointed upward and defined positive. This situation is known as the unstable period. At night (roughly between sun set and sun rise) the surface cools due to long wave radiative cooling. As a result heat from the atmosphere is transported downwards to the surface. Hence, H is negative. This situation is defined as the stable period. The LAS is able to measure the magnitude of the sensible heat flux (H) but not the sign, i.e. is H directed upward (> 0) or downward (< 0)?
There several ways to choose either the unstable or stable solution of H:
Net radiation: During most situations when the net radiation is positive, the atmosphere is unstable. Once the net radiation becomes negative the atmosphere becomes stable. Note that this option is not applicable over intensively irrigated fields.
Global/solar radiation: Although less accurate than net radiation data, but still useable. When the global radiation is higher than approximately 20 Wm-2, the atmosphere is unstable. When it drops below 20 Wm-2, assume stable conditions. The exact values are site/surface dependant.
Temperature profile data: for example air temperature data collected at 0.25m and 3m height. During daytime close to the surface (0.25m) it is warmer than higher up in the atmosphere (3m), i.e. unstable conditions (dT/dz < 0). At night the situation is opposite, cold close to the surface and warm at higher levels, the condition is stable (dT/dz >0). This method is the most reliable one, but requires accurate temperature measurements.
Cn2 data: During clear sunny days the Cn2-signal shows a very distinctive behaviour. Every time the atmosphere changes transition, the Cn2-signal drops to a very small value (® 1e-17). By determining the exact time when this occurs, the average time periods of unstable and stable conditions can be simply determined. During cloudy conditions the exact transition times are difficult to detect and is therefore difficult to automate.
The LAS manual shows a terrain classification for typical landscapes with corresponding surface roughness lengths. General meteorological literature can provide more detailed information of surface roughness length for specific surfaces and/or crops.
The surface roughness can also be determined experimentally, using e.g. eddy-covariance stations or from wind profile measurements.
This has been done, see publication by: McJannet, D. L., F. J. Cook, R. P. McGloin, H. A. McGowan, and S. Burn (2011), Estimation of evaporation and sensible heat flux from open water using a large‐aperture scintillometer, Water Resour. Res., 47, W05545, doi: 10.1029/2010WR010155.
But there are several reasons why LAS measurements of open water is rather complicated:
To measure both evaporation / latent heat flux and sensible heat flux directly (and without the restrictions when using a LAS on it own), a combined optical and microwave scintillometer can be used. This system measures both CT2, Cq2, and the co-variant term, CTq, between them, so no assumptions are made. Along with meteorological data from the receivers side mounted weather station, latent heat and sensible heat fluxes are calculated internally. See the Optical Microwave Scintillometer system page for more details.
How frequent the alignment has to be checked is dependent on the installation set-up. Tripods fixed in the ground can have the tendency to move, in particularly as the soil can become soft after periods of rain. In that case the alignment has to be checked at a regular interval. Once steel constructions are used on top of buildings, or tripods on a concrete foundation, the setup is much more stable and has to be checked less frequently.
In-case one has the ability to check the data in real-time, the demod signal can help to monitor the alignment. A slow decreasing trend of the demod signal can suggest possible changes in the optical alignment (ignoring degradation of the LED).
For a long term installation, stable steel constructions such as a steel frame or post, on a concrete foundation, are recommended to avoid vibration or miss-alignment. If tripods are used for field work, they should be fixed or tied to the ground when left unattended for a period to avoid damage from storms nocking the tripod over. To do this a ground anchor can be screwed into the ground under the tripod, and the tripod tied to this using a ratchet or cargo strap. Insure the tripod feet are firmly pushed into the ground first.
If there are animals in the area protect the equipment from being pushed over, disturbed, or the cables chewed, by surrounding the installation with electric fencing.
The Brewer azimuth tracker has a driving mechanism based on friction between the drive shaft and the drive plate. These items will get dirty over time and the azimuth tracker is likely to slip. This can be noticed by a tracker discrepancy after AZ or SR tests.
The drive mechanism can be cleaned by using a clean lint-free cloth with alcohol or with “garage” soap (soap with grains of sand in it). Switch the tracker power off! Remove the rear tracker cover (the cover on the side opposite to the power switch). Use the cloth with alcohol or soap to rub the dirt off the drive plate and the drive shaft. Rotate the tracker to clean the entire drive plate. Be careful not to break the wire of the safety switch. After cleaning the entire drive plate and shaft, rub them once more with a dry piece of clean lint-free cloth to remove any remaining residue of soap/alcohol.
When this is done, rotate the tracker to aim the Brewer approximately at the sun . Put the tracker cover back on and switch on the tracker power. Now the Brewer needs to perform some tracker resets. In the Brewer software, type “PD AZ SR 10” to perform these resets. Watch the data to check that the tracker resets without discrepancies and then put the Brewer software back into its normal schedule.
The Brewer instrument is capable of operating in different conditions from the tropics to the Antarctic. As the Brewer is used outside the whole year round, its Ozone measurements should not have any temperature dependency.
During the factory testing of the Brewer it undergoes a test in the temperature chamber from 0°C to +45 °C. Standard Lamp measurements are taken throughout this entire temperature range. This is a simulated Ozone measurement based on the halogen lamp inside the Brewer. Although the intensity of the lamp does change with temperature, the wavelength shift is negligible.
After the temperature test, the data of the SL measurements is analysed. During the analysis, the temperature correction coefficients are created. These coefficients compensate for the change in spectral response of the Brewer at the Ozone wavelengths. With the coefficients installed in the Brewer software, the Ozone measurements will not be affected by the temperature of the instrument.
The Brewer software will give this error message when it tries to make a HG measurement but cannot see the light of the Mercury lamp. There are several causes why the Brewer could give this error message. One of the motors could be in an incorrect position, so that the Brewer does not see the light. The PMT could not be measuring correctly or the lamp could need replacement.
The first step in troubleshooting is doing a full reset (RE command) in the Brewer software. Then try to perform the HG test again.
If the HG test still returns the error message one should find out if this also occurs for tests with the standard lamp. Type SL<enter> in the Brewer software.
If Both the HG test and the SL test fail, then either a motor is not moving correctly or there is a problem with the PMT/photon counting circuitry. Use the maintenance manual for further troubleshooting.
If the SL works but the HG fails, then there might be a problem with your lamp. For single board Brewers: Type AP to get the voltage of the Mercury Lamp (HG lamp). The voltage should be around 10 V. If the Voltage is off by 2 Volts, one should inspect the lamp.
The HG or mercury lamp is the lowest lamp in the lamp housing. Usually, if the lamp needs replacement, the glass will have black spots or the filament will be broken.
If the lamp needs to be replaced, do not touch the quartz envelope with your hands. Use a tissue or a piece of cloth. The lamp should be tightened firmly. Also, from the top, both filaments should be visible.
For the Brewer spectrophotometer, regular recalibration is necessary for the reliability of the Brewer’s Ozone measurements. The World Meteorological Organisation (WMO) recommends that each Brewer is calibrated at least once every two years. The Brewer is a stable instrument and drifts in the instruments can be monitored and corrected because of the diagnostic tests such as Standard Lamp and Dead Time measurements.
Some Brewer users prefer to have their Brewers calibrated every year. By doing this, they assure their Brewer data is of the highest quality. Drifts in the instrument are corrected sooner and the regular check with a reference Brewer increases the reliability of the data.
If you would like to discuss calibration of your Brewer at the factory or at your location please contact us.
The temperature dependence of the sensitivity is a function of the individual CHP 1. For a given instrument the response lies in the region between the curved lines in Error! Reference source not found. The temperature dependence of each pyrheliometer is characterized and supplied with the instrument. Each CHP 1 has built-in temperature sensors to allow corrections to be applied if required.
Typical Radiometer temperature dependence
RaZON+ is 100% operational ready. The only thing a customer has to provide is a 24VDC power supply.
There is a website hosted on RaZON+ that can be accessed on any device with Ethernet and Wi-Fi that has a web browser (pc, tablet or Smart phone)
The complete set-up and local check can be done on your smartphone or tablet.
Data logging is done via the Ethernet or RS-485 port.
No, only the sensors need calibration every 2 years. Because the sensors are smart you can easily exchange them with another sensor to prevent data gaps.
There are four ways:
1 minute averages for 365 days
Every two years, the RaZON+ sensors need calibration. They can be sent to Kipp & Zonen for recalibration
A firmware upgrade is planned for Q1 2017 to accept extra Modbus sensors (pyranometer, temperature sensors) and Modbus weather stations to expand the RaZON+.
The standard warranty of 2 years applies. However, you can register the PR1 pyranometer and PH1 pyrheliometer and extend the warranty on those instruments to 5 years.
To register go to www.kippzonen.com/register
When we calibrate the sensors there is no signal bounce other than the time that the pyranometer needs to reach its final value (time constant) if however there are electrical inferences and the shielding of the cable and data logger is not good then you can expect noise. A good way of testing this is by connecting a dummy pyranometer with the same cable (length and position) to the data logger. (Dummy pyranometer is a 1 kOhm resistor) This will show any interference coming from the cable.
This error is related to the zero offset type A. Normally this zero offset is present when the inner dome has a different temperature from the cold junctions of the sensor. Practically this is always the case when there is a clear sky. Because of the low effective sky temperature (<0 °C) the earth surface emits roughly 100 W/m2 longwave infrared radiation upwards. The outer glass dome of a pyranometer also has this emission and is cooling down several degrees below air temperature (the emissivity of glass for the particular wavelength region is nearly 1). The emitted heat is attracted from the body (by conduction in the dome), from the air (by wind) and from the inner dome (through infrared radiation). The inner dome is cooling down too and will attract heat from the body by conduction and from the sensor by the net infrared radiation. The latter heat flow is opposite to the heat flow from absorbed solar radiation and causes the well known zero depression at night. This negative zero offset is also present on a clear day, however, hidden in the solar radiation signal.
Zero offset type A can be checked by placing a light and IR reflecting cap over the pyranometer. The response to solar radiation will decay
with a time constant (1/e) of 1 s, but the dome temperature will go to equilibrium with a time constant of several minutes. So after half a minute the remaining signal represents mainly zero offset type A.
Good ventilation of domes and body is the solution to reducing zero offsets even further. Kipp & Zonen advises the CVF 3 Ventilattion Unit for optimal ventilation and suppression of zero offset type A. Using the CVF 3 zero offset type A will be less than 3 W/m2.
It is indeed possible to reach a value of 1400 W/m² or slightly higher. The maximum radiation from the sun above the atmosphere is 1367 W/m². However at high altitudes with a clear sky and some bright white cumulus clouds (not covering the sun) it is possible to get above the 1400 W/m². These clouds will act like a mirror and reflect (extra) solar radiation to the sensor and through this effect reach these high values. So it is possible, but only under these extreme conditions. Under a clear sky without clouds the radiation is definitely below the 1367 W/m².
Radiation incident on a flat horizontal surface originating from a point source with a defined zenith position will have an intensity value proportional to the cosine of the zenith angle of incidence. This is sometimes called the ‘cosinelaw’ or ‘cosine-response’ and is illustrated in figure 11. Ideally a pyranometer has a directional response which is exactly the same as the cosine-law. However, in a pyranometer the directional response is influenced by the quality, dimensions and construction of the domes. The maximum deviation from the ideal cosine-response of the pyranometer is given up to 80° angle of incidence with respect to 1000 W/m2 irradiance at normal incidence (0°).
If the Pyranometer remains horizontal the error involved is the directional error listed in the Pyranometer brochure.
For CMP 3 < 20 W/m2 and for CMP 22 < 5 W/m2
The CMP series can also be used under water, the depth is limited to 1 meter and can only be used for short measurements.
It is advisable not to keep the Pyranometer of the CMP series under water for longer than 30 minutes.
The SP Lite2 pyranometer and the PQS 1 PAR Quantum Sensor can be used for a longer period under water, the depth is limited to 2 meters. Please also take “breaking of light on the water surface” in consideration.
Yes, however the data logger needs to be placed on the surface (it is weather resistant, but cannot be lowered into the water).
We advise to re-calibrate the Pyranometer every two years.
The 50 % points are the wavelengths where the output of the instrument is 50 % reduced with 100 % input.
The instrument has an analog output, therefore the resolution is infinite. Every change is noticed, no matter how small it is.
The bandwidth of most pyranometers is 285 to 2800 nm. This covers the full solar spectrum as shown below.
There are some exceptions:
The disturbance on the cables on the CMP 11 is difficult to judge from a distance. A test would give the best criteria in this case.
Simply cover the CMP 11 so it is fully dark (in box with cloth etc.) Log the data over a period that disturbance is expected, at least one day.
If the data is zero no problem is to be expected.
No, we do not have filters for any of our pyranometers. The only way to do this in a correct way is to use a filter dome. Otherwise the directional response would be affected.
The AMPBOX is the best solution.
You will need a suitable PSU and a shunt resistor of 500 Ω to convert the current output (4..20mA) to a voltage output of 2-10V , or you will need a shunt resistor of 50 Ω to convert the current to a voltage output of 0.2-1V.
CMP 6 in combination with PQS1 PAR Quantum Sensor is advised. CMP 6 for outside usage to measure Global solar radiation. PQS1 to measure PAR radiation inside which is most sensitive for plants and crops.
For this application the CMP10 and SMP10 are advised as they have an internal drying cartridge that will last for at least 10 years.
Please note that the pyranometer needs to be mounted in the same angle (POA) as the PV panel.
For users that prefer the desiccant visible Kipp & Zonen offers the CMP11 and SMP11 with visible and user changeable desiccant.
None, solar concentrators are reflecting the direct solar radiation to a concentrator and are tracking the sun. You will need a pyrheliometer on a sun tracker to measure direct solar radiation.
Yes, we do have a Pyranometer with the same spectral characteristics as a PV panel. This is the SP Lite(2) Pyranometer.
Our SP-Lite is based on a silicon diode which has a response from 400 – 1100 nm.The advantage is the response time, which is as fast as any PV panel ( milli seconds).The disadvantage is that not all PV panels have the same spectral range. A thermopile pyranometer covers the full spectral range of the sun and will give a more accurate measurement of the total (global) solar radiation.
The output from thermopile Pyranometers, such as our CMP Series, is very low – typically around 10 milli-volts on a clear sunny day. To resolve changes of 1 W/m2 requires an ADC with an accuracy and resolution of around 5 micro-volts. These PC interfaces are very expensive and difficult to find in a form that is easily interfaced to the PC. This is why meteorological data loggers are normally used that can cope with the low signal levels.
Kipp & Zonen has solutions like handheld- or fixed location data loggers.
The CMP 6, as with all our solar radiometers based on thermopiles has a continuous small analoge voltage output. For CMP 6 an irradiance of 1 W/m2 generates an output signal in the region of 5 to 15 micro-volts. We have additional solutions to increase this voltage.
NIST in the USA supplies calibration services to industry – in case of light they characterise sensors, detectors and lamps for use in manufacturing and for luminance measurement (LUX).
They are not set up for the calibration of sensors for solar radiation and they are not a traceable reference.
The only accepted world standards for the calibration of radiometers for the measurement of global or direct broadband solar radiation are as below:
ISO 9060 Specification and Classification of Instruments for Measuring Hemispherical Solar and Direct Solar Radiation
ISO 9846 Calibration of a Pyranometer Using a Pyrheliometer Guide to Meteorological Instruments and Methods of Observation, Fifth ed., WMO-No. 8
By physical laws any object having a certain temperature will exchange radiation with its surroundings. The domes of upward facing radiometers will exchange radiation primarily with the relatively cold atmosphere. In general, the atmosphere will be cooler than the ambient temperature at the Earth’s surface. For example, a clear sky can have an effective temperature up to 50°C cooler, whereas an overcast sky will have roughly the same temperature as the Earth’s surface. Due to this the Pyranometer domes will ‘lose’ energy to the colder atmosphere. This causes the dome to become cooler than the rest of the instrument. This temperature difference between the detector and the instrument housing will generate a small negative output signal which is commonly called Zero Offset type A. This effect is minimized by using an inner dome. This inner dome acts as a ‘radiation buffer’.
The Zero Offset A can also be reduced by using a Ventilation Unit CVF 3.
No, all the Pyranometers have a 180 degree field of view. When mounted horizontally, they cannot see light reflected from the ground due to its design.
The CMP 11 uses a default temperature compensation setting and the dependency is ±1% from -10 to +40°C.
The CMP 21 is individually tested and the temperature compensation is optimised. It is ±1% from -20 to +50°C. However, from -10 to +40°C it is within ± 0.5%, typically ± 0.3%. In addition a temperature sensor is fitted and the temperature response curve is supplied. Each CMP 21 has the directional (cosine) response tested, and this is also supplied. This means that for the serious scientist the irradiance values can be corrected for temperature and solar elevation – increasing the accuracy. This is not possible with the CMP 11.
BSRN requirements state that the solar radiometers must be fitted with an internal temperature sensor and the data recorded, so CMP 21 is compliant to this, but CMP 11 is not.
Our thermopile-based instruments, including the CMP range of pyranometers and the CH(P) 1 pyrheliometer, do not require power to operate. They generate a small voltage output in response to the solar radiation.
The CGR 4 differs from all other Pyrgeometers in that it allows accurate daytime measurements on sunny days without the need for a shading device. Due to the unique construction of the CGR 4, solar radiation of up to 1000 W/m² induces window heating of less than 4 W/m² in the overall calculated downward radiation. In the Baseline Surface Radiation Network (BSRN) manual (WMO/TD-No.897) an extended formula is described. This formula corrects for window heating and so called “solar radiation leakage”. Due to the very low window heating offset and optimal spectral cut-on wavelength, these corrections are not necessaire for the CGR 4.
We advise to re-calibrate the Pyrgeometer every two years.
More information about our calibration service can be found here.
If the CVF 3 is used for a Pyrgeometer the effect of sunrise is not valid and continuous 5 Watt is preferred. In extreme cold climates , polar / mountain tops, the 10 Watt heater can be used continuously.
Yes. Normally 4 of these side-mounted sensors is the maximum, however we are able to make an extension on one pyrheliometer mount for the extra sun-sensor.
The power use of the 2AP itself is about 1.5 A to 2 Amps. (internal fuse is 3 Amps slow)
The power use of the 2AP itself is about 1.5 A to 2 Amps. (Internal fuse is 3 Amps slow)Part number for the 24V heater kit is: 12136346.This kit contains two 50 Watt heaters.So the current for these heaters is 4.2 A (at 24V), fuse is 5 A slow blow.If we add up the total power we have:5A (heaters) + 3.15 (2AP)= 8.15 ANormal conditions:4.2 A (heaters) + 1.25A (2AP) = 5.5 A normalTherefore a 5 Amp power supply will not survive very long.We recommend to take a power supply that can deliver the 8.15 A. (when heaters are used)
The 2AP works fully autonomously, after the setup. Setup is done in combination with a PC. (Entering Longitude, Latitude etc.) Indeed a data logger is needed to collect data from the sensors, but this logger has no (hardware) connection with the 2AP.
To connect the 2AP with a PC for communication, a 3-wire cable is used (or 2 wires plus shield) as described on page 5 of the manual.Advised is a shielded cable, where the shield can be the ground connection.
This cable length can be 30 meter. We can supply this cable, but it can be bought "around the corner".The communication software is included with the 2AP.
The CMD and sun tracker software will work on COM1 or COM2 only, specified as the first parameter after the program name in the command line. Make sure the 2AP is connected to one of these two ports. Problems can also occur if another program has taken over the COM port and will not give it up. Also, some Compaq computers have non-standard COM ports, which the CMD and sun tracker programs cannot communicate through. The solution for this problem could be found in a simple add-on card with a standard extra serial port, if it can be set as COM 1 or 2.
The temperature range for the 2AP tracker is:Standard temp range: 0 - 50 degrees CelsiusWith cold cover: -20 - 50 degrees CelsiusWith cold cover and heater -50 - 50 Degrees CelsiusNormally the heater is built in, in the factory. However we can supply you with a kit plus instructions to do it yourself.
The 2AP has the following errors:
The first 2 are user controlled and the last 2 are fixed.Assuming that the leveling is done optimal the only error remaining that can be corrected is time. If we assume that the clock is reset every 1,000,000 seconds (11.5 days) there will be an expected error of 5 seconds. If we assume that the sun rotates 360 degrees in 24 hour then RMS 0.72 * 5 seconds = an actual time error of 3.6 seconds. For a period of 11.5 days the total time error contribution is 0.015 degrees (the diameter of the solar disk is 0.25 degrees). Per year this would result in 0.5 degree.If this time correction and the check on leveling are done on a regular interval there is no need for a sun sensor. If however this interval can or will not made, the sun sensor will correct for both (leveling and time).The sun sensor is normally used for first checking the tilt error. Assuming that there is sunshine for at least 2 full days over the full day. This information is stored in an internal log file and used to correct (in combination with PC). Over this period the user has to correct time. (if more than 2 weeks). After this initial run and correction for tilt, the sun sensor is used for time correction. This means that optimal accuracy is maintained without user (time) correction. This means that the 2AP is within specs the whole year without intervention.Please note that the sensors used on the 2AP also need maintenance on a regular base (drying cartridge and dirt on domes).Better than giving an error in percentage we would like to show the benefit of not having to correct to clock. The 2AP error in degrees can be calculated as percentage of 360 degrees, but the error in sensor reading depends on the type of sensor.
The controller board has a temperature compensated oscillator module for the microprocessor. While power is applied the firmware keeps accurate time and updates the real time clock (which is not very accurate) every 8 hours.We enter a room temperature correction, which compensates for initial calibration of the oscillator module. The oscillator module can drift up to ±11 ppm over the 0 °C to 70 °C temperature range. The module can also drift up to ±2 ppm in a year.The temperature drift is different for each oscillator so cannot be compensated for in firmware.
The air pressure that is required should be an average value for the site the instrument is operated. It does not need to be updated over time. The meaning of it is to correct for (a small) optical shift due to atmospheric pressure. A normal value depends of course on the heath of operation. A value of 1000 mBar is typical for sea level.
You can try the following:If you send the command “CO”, the 2AP will cold start. This means ignore all present settings and start without using any previous (possibly wrong) settings.If you then start the sun tracker program, it will start up with the message “”recovering from cold start””Then longitude and latitude etc. will be recovered from the .ini file, the time and date of course cannot be stored and has to be entered again. If no further error message is given, the 2AP is most likely operational again.
This could solve the problem, if not please contact us and we will discuss further options.
The 2AP BD altitude specification (2000m) is limited by the CE and CSA (Canadian Standards Association) recommendation for main power board design. CSA recommends that AC boards have certain spacings between the board tracings for various elevation (pressures). As the pressure decreases there is more probability for arcing when the wires are close. Unfortunately there is not enough room internally, in the 2AP BD, to increase the size of this board (to make the spacings bigger).The best solution is to sell/quote a 2AP Gear Drive with 24VDC, as this would eliminate the altitude restrictions associated with high voltage AC.
Standard one CHP 1 mount is included. An extra mounting clamp can be added on top of this CHP 1 mounting. The same can be done on the other side. So standard, 4 CHP 1’s is possible.
The SOLYS Gear Drive can easily handle more, but for mounting more instruments (e.g. 8 pyrheliometers) a larger mounting plate is required.
Pointing accuracy is better than 0.02°, when active tracking, under all conditions.
Yes, like on the SOLYS 2 a special mounting clamp is available for the PMO-6.
The power supplies used in the SOLYS have EN60950-1 approvals. This means approved up to 5000m. If higher altitudes are required we can check or test if this is feasible.
It takes a few minutes for the SOLYS to return to its home position. Then the SOLYS goes to sleep mode (for power reduction).
Yes, both the Solar Zenith and Azimuth positions and the SOLYS motor Zenith and Azimuth positions are available in the log file.
The power requirement is for both AC and DC is 25 Watt during operation and 13 Watt at night. For the SOLYS “night” is from ~ 5 minutes after sunset to ~ 5 minutes before sunrise.
When used in cold climates, the heater switches on to keep the interior above -20°C
This is switched automatically and only used when powered from AC.
The cold cover can be used to reduce the required heating power.
The Sun Sensor is supplied as standard with the SOLYS Gear Drive. It can be removed (or not mounted) then the SOLYS will follow the sun based on its internal calculation.
This is normally accurate enough, but does not correct for any misalignment or unstable mounting.
Like our radiometers, the SOLYS’s are made of anodised aluminium. Until now we did not see any effect on the functioning of the trackers that are mounted on the sea shore.
The SOLYS has in addition to the radiometers a paint coating to further protect it.
Absolutely! Great care has been put in extending the temperature range and minimising the possible disturbance from dry air (ESD) to make the SOLYS Gear Drive suitable for this climate.
Filters can be ordered in sets of 5.
The AMPBOX can be delivered in two versions:
The AMPBOX has a 20 bits A/D on the input and a 16 bits A/D on the output.
The maximum error from the AMPBOX is ±0.05% of span or ±10 µV (over the full temp range)
This means in daily use that the additional error of the AMPBOX is far below 1 W/m2 for all radiometers.
The gain range is the ability to adjust the amplification to the sensitivity of the radiometer:
As mentioned above the amplification can be adjusted to 0- 1600 W/m2 = 4 – 20 mA.In this case 100 W/m2 change on the input gives 1 mA change on the output.The benefit is that two different sensors with different sensitivities have an identical output from the AMPBOX.
The zero adjust is used for the pyrgeometer to allow negative inputs.The pyrgeometers are adjusted for -300 to +100 W/m2 = 4 to 20 mA.So 100 W/m2 change on the input gives 4 mA change on the output. The zero point for the pyrgeometer is set to 16 mA. This is because a pyrgeometer can be more negative than positive.
To keep the outer dome at the same temperature as the surrounding air temperature. This will keep the zero (a) offset as low as possible. But also to keep the dome as dry and clean as possible (from rain snow, ice and dirt).
Advised is to use the 5 Watt heater to keep the offset (a) as low as possible. This can be used during the whole day. If the surrounding temperature is above zero this could be sufficient. Below zero degree Celsius the extra 5 Watt (10 Watt total) can be used. We recommend to use the 10 Watt heater only during the morning (few hours around (preferable before) sunrise) to get the dome clean when measurement starts. After that the heater can be set back to 5 Watt.
Yes you can, by using a shunt resistor and a suitable power supply unit (PSU). You will need a shunt resistor of 500 Ω to convert the output current (4..20mA) to a voltage output of 2-10V. Or you will need a shunt resistor of 50 Ω to convert the current to a voltage output of 0.2-1V.
The AMPBOX is set for 0 - 1600 W/m2 for 4 – 20 mA
For CMP 3 with 16.51 μV sensitivity, this is 0 - 16.51 * 1600 μV =0 - 26.416 mV for 4 - 20mA (delta = 16 mA)
Sensitivity AMPBOX = 26.416 mV per 16 mA = 1.651 mV per 1 mA or 1651 μV per 1 mA
Now connected PAR with 5.59 μV/μmol. 1651 / 5.59 = 295.35 μmol per mA
0 μmol = 4 mA
295.35 μmol = 5 mA etc.
4725.6 μmol = 20mA as maximum input
No, 0,1 μmol/m²s input will result in a very small change on the output of the AMPBOX (around 4,00033 mA). This is outside the accuracy of the AMPBOX and the accuracy of the PAR Lite.
No, the METEON will not work together with an AMPBOX.
With a 10 Ohm resistor the 20 mA output from the AMPBOX can be converted to 0.2 V max signal (max for the METEON). But the METEON cannot deal with the zero offset from the AMPBOX (4 mA).
If the AMPBOX is purchased together with a new pyranometer, or for use with an existing pyranometer, it has the sensitivity of that pyranometer programmed internally. In this case 0-1600 W/m2 of irradiance on the pyranometer produces 4-20mA from the AMPBOX. The serial number of the pyranometer matching the AMPBOX should be present on a label on the AMPBOX.
No, it cannot separate UV-A from UV-B, it measures both together, for measurement of these parameters individually we recommend our UVS Series of radiometers.
We advise to re-calibrate the UV radiometers every two years.
No, the input range of the METEON is limited to 200 mV (the output from the UVS-X goes up to 3V)
The ‘Mean Adjustment Factor’ on the calibration certificate is equivalent to the sensitivity of a pyranometer. It applies to specific Ozone column and Air-mass (solar elevation) values used as the standard test conditions. Data files are provided to correct the measured values for other Ozone and Air-mass conditions (see Radiation Amplification Factor).
No, we do not have a UV-C sensor. UV-C from the sun is almost completely absorbed by Ozone in the atmosphere and virtually none reaches the ground.
Actually our thermostat is better than a temperature compensation. We used to have UVS-X-C versions of our instrument (these were temperature compensated). We stopped that line because the UVS-X-T version performed much better. Temperature compensation means correcting the output for changes in sensor temperature. Because our sensor is always the same temperature there is no compensation required. The internal Peltier element heats or cools the actual complete detection system that measures the UV light.
The bandwidth of the CUV 4 is 280 - 400nm. The 50 % points are defined to be 290 - 385 nm.
The radiation amplification factor is a correction for solar zenith angle and Ozone column. This is required because these two factors strongly influence the UV measurement.
The UVIATOR can work with any data logger that is capable of storing UVS measurements. The UV-data must to be stored in the correct format, and Campbell loggers can do this. More details can be found in the UVIATOR manual.
For easy correction for solar zenith angle and Ozone column.
This is required because these two factor strongly influence the UV measurement. With the UVIATOR software you can collect the Ozone column data from the OMI satellite data per date, time and location. With this Ozone data and the solar zenith angle the UVIATOR will calculate the optimal correction for every data point.
The UVS series of UV radiometers have an output in the range from 0 - 3 V.
No. According to the WMO / WHO guidelines for the Global UV Index, UV-I should only be derived from UV-E measurements (or from a spectral instrument such as our Brewer Spectrophotometer).
Yes, the UVS-AB has two independent detection systems.
The UVS-AB has two continuous, simultaneous, analog outputs; one for UV-A and one for UV-B. See below drawing of the UVS-AB for details.
Beneath the dome and diffuser two sets of filters and detectors are positioned. Detector 1 is 4 times bigger than detector 2. Detector 2 is located exactly in the middle, on top of detector 1. Filter 1 has an opening in the middle for filter 2 plus detector 2. In this way we can make sure both detectors have a 180 degree field of view.
Sometimes it happens that the colors of the cables are different when you order extended cables. Usually there is added a page in the manual where this is mentioned.Standard = extendedWhite = whiteGreen = blueBlack = black
The correction factor in the manual could indeed be written more carefully. It says dividing by (1+x.V3/4) this refers to the calibration factor. Better is to say the output should be multiplied with a factor (1+x.V3/4).
There is no general value to use but some criteria to keep in mind to select a Pt-100 current.Because the Pt-100 (unlike a thermocouple) needs current, it is advised to keep this current as low as possible to avoid self-heating of the Pt-100 by its own current. The Pt-100 measuring device (like our data loggers CC 48, CR10X) has a fixed current, in such a way that the voltage over the Pt-100 is matched with the Pt-100 (voltage) measuring input of these loggers.In general the current for a Pt-100 is indeed between 0.1 and 1 mA. This would result (@ 0ºC) in a voltage over the Pt-100 of 10 mV or 100 mV. Therefore the current can also be selected depending on the available input range of the measuring device. The error introduced by self-heating, when using a 1 mA current, is quite low (< 0.2ºC) also because the Pt-100 is very well connected to the body of the CNR1. When the heater of the CNR1 is on, the error introduced by the heater in measuring the body temperature is typical 2ºC (see manual).The benefit of a larger current (1 mA) is that electrical disturbances have less effect when the current is larger.To summarize these facts I would say, 1 mA measuring current is accurate enough, but the output voltage in this case (0.1 Volt) has to match the measuring input range.
Response time for CNR1 sensors: 5 s (63%) en 18 s (95%)
Both instruments use thermopiles, but the dome over the thermopile determines what kind of radiation passes through and reaches the thermopile. A thermopile is normally protected by a single or double dome to reduce offsets caused by sudden temperature changes like wind.
The CNR 2 uses two glass domes to cover the pyranometer and two silicon domes to cover the pyrgeometers. It uses TWO thermopile detectors (1 for each of the two pyranometers and 1 for each of the two pyrgeometers) and provides two separate outputs. One NETTO for short wave (solar spectrum) and one NETTO for long wave radiation.(Far Infrared spectrum).
So yes, the CNR 2 has separate thermopiles to measure Far Infrared and Solar radiation and so do the other CNR net radiometers.
The detector from the NR Lite(2) is not protected and I sin direct contact with the weather conditions. Therefore it cools down a lot faster by the wind, which effects the accuracy of the measurements. The NR Lite(2) uses NO dome. It uses only TWO detectors with a PTFE coating and provides ONE single output for NETTO short wave- and long wave radiation. It uses one thermopile to measure the full spectrum of Far Infrared and solar radiation.
The difference between the NR Lite(2) and CNR 2 lies in the material used to cover the thermopiles.
CNR 2 uses glass domes for the pyranometers (that measure short wave radiation) that have a bandwidth of 300 nm to 2800 nm. It uses silicon domes for the pyrgeometers (that measure long wave radiation) that have a bandwidth of 4500 nm to 42000 nm. This leaves a gap between 2800 nm and 4500 nm. This is the so called atmospheric window where very little radiation comes in (see picture below).
The NR Lite(2) uses NO domes. It uses two detectors with a PTFE coating which have a bandwidth of 200 nm to 100.000 nm.
We do not have charts or tables indicating irrigation requirements for various plots of land (i.e. based on differing vegetation and climatic factors). There are many scientific publications that refer to evaporation rates from crops, but none, to our knowledge, that specifically link PAR readings from our sensor to irrigation.
There is something as a "reference crop evaporation" or "actual evaporation" that can be derived from net radiation (solar plus thermal) together with surface temperature, soil and vegetation data. Unfortunately we don't have the information how to do it. There is a simpler approach in which the expected evaporation is coupled to the total dose of global radiation as measured by a horizontal pyranometer.
If the metoffice gives such figures for your area it should be of importance to know the relation between PAR intensity and total global irradiance for at least a solar spectrum at air mass 1.5 (solar elevation 53°).
This relation is for:
Clear sky: 681 W/m² total, 308 W/m² in the 400 to700 nm band 1408 µmol/s.m² PAR
Light cloud cover: 200 W/m² total, 109 W/m² in the 400 to 700 nm band 493 µmol/s.m² PAR
Be aware that many green leaves are highly reflective for near IR but absorb strongly in the 400 to 700 nm band (PAR region). For evaporation only W/m² counts and for photosynthesis only photons counts.
Normally 1 should be enough. If in the greenhouse the conditions differ, like different glass type, shielding or glass cover, it is advised to use more than one PQS 1 PAR quantum sensor per typical condition.
Yes, however the depth is limited to 2 meters. Please also take the “breaking of light on the water surface” in consideration. This affects the calibration factor.
Yes, however the data logger needs to be placed on the surface (it is weather resistant, but cannot be lowered into the water).
We advise to re-calibrate the PQS 1 (PAR Lite) radiometer every two years.
0,001 µmol represents a voltage of 5nV (nano Volt). As you can understand this very low voltage cannot be measured with a data logger. Besides the absolute error from the data logger, the PQS 1 PAR quantum sensor (PAR Lite) also has some specifications to consider.
There is the non- stability, non linearity, temperature dependence and the quantum response. Measurements under 1 µmol/m²s are not to be trusted as accurate. (effective limit)
The extension is .TXT or .XLS. Using the software interface you can select to save this as a text -or Excel file.
The format uses columns, for example:
The picture shows how a PT100 is connected. PT100 uses four input channels nr 1,2 ,3 and 4. Leaving 4 channels left, nr 5,6,7, and 8, to connect other sensors.
Please note that the picture uses 2 analogue inputs for the instrument (differential). Of course you can decide to use it single ended, by connecting the – from the instrument to the GND.
The LOGBOX SD has one input for power. You either connect the internal battery or an external power source. So external power will not switch of the battery.
PWR OUT will provide whatever power is connected as power source for the LOGBOX SD.
Every logger has an A/D converter with a certain resolution (number of bits) - often 10, 12, 16 or 24 bits resolution. A logger also has a fixed number of analog input ranges - often 20 mV, 100 mV, 1 V, 5 V and 10 Volt ranges.
For example we use a logger with 12 bits resolution and 5 Volt input range. This means that the 5 Volt is divided in 2¹² steps. This is 5/4096 = 0.00122 Volt per step. So the smallest detectable change on the input is 1.22 mV.
If we connect an SP Lite(2) with a sensitivity of 75 microVolt/W/m^2, one Watt (change) will give 0.075 mV (change) on the output. So we need a change of 1.22 / 0.075 = 16.2 Watt/m² before we see a change in the Logger output.
As you can understand this is not acceptable. A minimum of 1 W/m² should be detected (preferably a factor 10 times better). This can be achieved by lowering the input range to 100 mV (50 times better). Or by selecting a higher resolution e.g. 16 bits (in stead of 12 bits) this is 16 times better ( 2¹⁶- 2¹² = 2⁴ = 16 ).
No, the METEON will not work together with the AMPBOX. With a 10 Ohm resistor the 20 mA output from the AMPBOX can be converted to 0.2 V max signal (max for the METEON). But the METEON cannot deal with the zero offset of the AMPBOX (4 mA).
Yes, inside the software, at the graphical chart, there is an export button. You can select the default .txt option or customize the extension into .xls.
No, the output of the UVS is 0-3V and this is too high for the METEON.
The logging interval can be selected from 2 to 65.535 seconds.
Two AA size internal Alkaline batteries will operate for approximately 1200 hours / 50 days.
With two AA size internal Alkaline batteries.
The METEON is not suitable for unprotected outdoor use. However, the operating temperature range is – 10 ºC to + 40 ºC. When it is placed in an enclosure protected from dust and rain, it would be possible in practice.
The SOLRAD can be used as a very cost-effective and well performing real-time interface to a PC serial port, logging the data on the PC with the supplied software.
The METEON however, cannot do this. You need to download the data periodically using the supplied software. The METEON interface is USB.
Please check the calibration factor of the pyranometer which is set in the METEON. A wrong calibration factor of the instrument will result in wrong measurements. Also check if the correct instrument is selected.
Adding the intervals without dividing this by the (interval) time.
For example: Radiation in the morning 4 hours 400 W/m². Radiation in the afternoon 4 hours 600 W/m². If you would take a 60 minute interval on the same day: Morning = 4 intervals of 400 W/m2 Afternoon = 4 intervals of 600 W/m2 Total over the day 4 x 400 + 4 x 600 = 1600 + 2400 = 4000 W/m2 (over hourly interval) This is 4000 W/m2 per hour or 4000 Wh
The stored interval in METEON is 30 minutes. During the morning you will get 8 intervals of 400 W/m2 During the afternoon you will get 8 intervals of 600 W/m2 16 intervals (of 30 minutes) with a total of 8 x 400 + 8 x 600 = 8000 W/m2 (over 30 min interval) This is 8000/2 = 4000 W/m2 per hour or 4000 Wh
Yes, the SOLRAD is perfect because it has a 0-10V input range available (the output of the UVS meter is 0-3V ).
Please consider that the SOLRAD is intended to display real-time values and/or to store the integrated values for a day. If you fully want to use data logger options it is better to use a LOGBOX SD.
The UVS has a ‘Mean Adjustment Factor’ on the calibration certificate. This is equivalent to the sensitivity of a Pyranometer. This can be entered into the SOLRAD and the readings will be in W/m2.
The SOLRAD is not a data logger. It is intended to display real-time values and/or to store the integrated values for a day. 31 records allows a month of daily integrated values to be stored.
The internal battery will only run it for a little more than one day. For longer periods it requires an external DC supply.
It is not suitable for unprotected outdoor use. However, if it is in an enclosure protected from dust and rain it would be OK in practice.
This depends on the number of recorded channels and storage interval. A detailed description of the storage capacity can been found in the COMBILOG manual, available on it's product page.
In case you want to quickly calculate the storage capacity in days for your application, please use the calculation tool below.
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