Institute of Applied Physics Atmospheric Research Group A T M O S P H E R I C

About the project

Characteristics of the measuring equipment

Automatic solar tracking platform 2AP BD (Kipp&Zonen, the Netherland ) with sensors for diffuse and direct solar radiation measurements.

Automatic solar tracker unit 2AP BD (Kipp&Zonen BV, the Netherlands)
To carry out measurements for direct and diffuse components of incoming solar radiation we need to use an active solar tracking system equipped with pyrheliometer(s) and pyranometer(s), and Shading Arm Kit. The 2AP BD tracker is an all-weather, reliable and affordable tracking and positioning instrument. It is widely used in typical applications which include solar tracking as a part of Scientific Solar Monitoring Station.
   Fully automated system with two stepper motors (in azimuth and zenith directions) is used simultaneously for precise pointing pyrheliometers at the sun ( direct irradiance measurement) and for shading pyranometers (diffuse irradiance measurement); accuracy of tracking < 0.15°, resolution reaches the value of 0.0036°. 2AP BD unit runs unattended for a long period of time after initial setup and it requires only occasional checks of the internal clock.
The pyranometer CM 11 for measurements radiation in W/m2
  • Spectral range 305 2800 nm (50% points)
  • Sensitivity 4 - 6 V/W/m2
  • Impedance (nominal) 700 - 1500 ohms
  • Response time (95%) 15 sec.
  • Non-linearity < 0.6% (<1000 W/m2)
  • Temp. dependence of sensitivity < 1% (-10 to +40 °C)
  • Directional error < 10 W/m2 (beam 1000 W/m2)
  • Tilt error None
  • Zero-offset due to temp. changes < 2 W/m2 at 5 K/h temp. change
  • Operating temperature -40°C to +80°C
  • ISO-9060 Class Secondary Standard
  • Dimensions W x H 150.0 mm x 91.5 mm
  • Weight 850 grams
  • Cable length 10 m
Pyrheliometer CH 1 for measurements direct solar radiation in W/m2
  • ISO classification First Class
  • Maximum irradiance 4000 W/m2
  • Spectral range 200 - 4000 nm (50 % points)
  • Sensitivity (nominal) 11 V/W/m2
  • Impedance (nominal) 50 - 70 ohms
  • Response time (95 %) 7 s
  • Non-linearity 0.2 % (0 - 1000 W/m2)
  • Temp. dependence of 1.0 % (-20 °C to +50 °C) sensitivity
  • Zero-offset due to temp. changes 3 W/m2 at 5 K/h temp. change
  • Full opening view angle 5 0.2 (acc. to WMO)
  • Slope angle 1 0.2 (acc. to WMO)
  • Required tracking 0.5 from ideal accuracy
  • Operating temperature -40 °C to +80 °C
  • Traceability WRR
  • Weight 700 g
  • Cable length 10 m
UV-S-B-C Radiometer for measurements of solar ultraviolet UVb radiation in W/m2
  • Spectral response 280 315 nm
  • Sensitivity of (nominal) as 1 V output corresponds 1.8 W/m2 UV-B
  • Temperature dependence 0.15 %/°C
  • Response time (99%) 0.5 s
  • Non-stability (% change/year) max 3 %
  • Non-linearity (over full measurement range) max 0.05 %
  • Contribution at wavelengths >400 nm <0.1 % of output
  • Expected accuracy for daily sums max 5 %
  • Cosine response error max 2.5 % (between 0 and 70° zenith angle)
  • Output - Analog voltage proportional to irradiance
  • Operation temperature range -40 to +50 °C
  • Supply voltage 6 32 VDC (5 mA)
  • Zero offsets (no UV radiation exposure) max +/- 2 mV
  • Impedance (nominal) 500 ohms
  • Expected signal output in atmospheric measurement conditions max 3 V
  • Material Case: protected aluminium, polyester coated; Dome: quartz
  • Cable length 10 m; Optional: 20 m (max. length)

Stationary platform with sensors for global solar radiation measurements and with datalogger CR10X-4M

The CG 1 Pyrgeometer for IR (infrared) radiation measurement
  • Sensitivity (nominal) 14 V/W/m2
  • Spectral Range 4.5 42 m
  • Window Heating Offset (under direct solar irradiance) 25 W/m2 (nominal)
  • Operating Temperature -30 °C to +40 °C
  • Response Time (1/e) < 8 s
  • Thermopile Output Range -250 to +250 W/m2
  • Temperature Dependence of Sensitivity 2 % (-20 °C to +30 °C)
  • Thermal Gradient Offset 1 W/m2 (5 K/h)
  • Field of View 150 degrees
SP Lite for routine measurement of solar radiation
  • Spectral range 400 - 1100 nm
  • Sensitivity (nominal) 100 V/W/m2
  • Response time less than 1 s
  • Max. irradiance 2000 W/m2
  • Temperature dependence +0.15 %/°C (typical)
  • Operating temperature -30 °C to +70 °C
  • Directional error 5 % at 80 degrees
PAR Lite is designed for outdoor measurement of photosynthetically active radiation (PAR) in natural daylight
  • Range 0 ... 10.000 umol/m2s
  • Sensitivity (nominal) 4 ... 6 µV/µmol/m2s
  • Spectral range 400 ... 700 nm
    • cut on 400 15 nm
    • cut off 700 15 nm
  • Spectral response matching error (450 ... 650 nm) 10 %
  • Directional error (up to 80 degrees) 10 %
  • Response time less than 0.1 s
  • Operating temperature -30 °C to +70 °C
  • Temperature dependence of sensitivity -0.1 %/°C (typical)
UV-S-A-C Radiometer for measurements of solar ultraviolet UVa radiation in W/m2
  • Spectral response 315 400 nm
  • Sensitivity of (nominal) as 1 V output corresponds 75 W/m2 UV-A
  • Temperature dependence 0.1 %/°C
  • Response time (99%) 0.5 s
  • Non-stability (% change/year) max 3 %
  • Non-linearity (over full measurement range) max 0.05 %
  • Contribution at wavelengths >400 nm <0.1 % of output
  • Expected accuracy for daily sums max 5 %
  • Cosine response error max 2.5 % (between 0 and 70° zenith angle)
  • Output - Analog voltage proportional to irradiance
  • Control output for internal temperature 2.5 V ~ 25 °C
  • Operation temperature range -25 to +50 °C, full spec.; -40 to +50 °C, reduced spec.
  • Supply voltage 7 18 VDC (8 W)
  • Zero offsets (no UV radiation exposure) max +/- 2 mV
  • Impedance (nominal) 500 ohms
  • Expected signal output in atmospheric measurement conditions max 3 V
  • Material Case: protected aluminium, polyester coated; Dome: quartz
  • Cable length 10 m; Optional: 20 m (max. length)
Data Logger CR-10X 4M (Campbell Scientific Co. ,UK)
   Data Logger CR-10X 4M is a rugged instrument with a research-grade performance. CR-10X 4M is a rugged measurement and control system that delivers accurate, reliable measurements in a variety of applications. Such characteristics as the measurement precision, flexibility, long-term reliability, and economic price of the Data Logger CR-10X 4M, make this instrument highly suitable for our research activity, and measurement and store applications.    The instrument has precise 13 bits A/D converter of signals, assures of 0.1% accuracy; fulfills data acquisition, temporary stores in battery backed 128K memory extended up to 4 Mb (with using non-volatile Flash memory card) and transfers data to PC through direct links using SC32A RS-232 Interface. Data logger has 12 single ended mV inputs with common ground or 6 fully floating differential inputs, which are individually configured. Channel expansion is provided by low level voltage AM25T multiplexer on 25 differential voltages in one differential input channel. Extensive calculation functions are available. Scan rates are programmable from 1/64 sec to 2.5 hours. Output intervals for row or processed data are user-specified. Full scale of analog inputs ranges from +/- 2.5mV to +/- 2.5V. Memory extension up to 2Mb will allow to carry out measurements in unattended regime for 2-4 months depending on number of channels used by sensors and other devices.
   Our configuration: memory extension up to 4 Mb(external), number of channals - 9, type of channals - differential, sample rate - 1 sec, interval of averaging - 1 min.

Automatic weather station MiniMet  with DataHog 2 datalogger.

Portable automatic weather station MiniMet (Skye Instruments, Ltd., UK).
   To supplement data sets obtained from long-term continuous measurements of solar irradiance it is necessary to utilize ground based weather station for measurements of main meteorological parameters.
   MiniMet is a modular multi-channel weather station for environmental monitoring. It is equipped with the following sensors: wind speed and direction, air pressure, temperature and relative humidity, solar radiation (pyranometer) for wavelength spectrum range from 280 to 1100 nm , and with the UV-B radiation sensor. It also includes data logger DataHog 2 with 15 bit A/D conversion of signals. Data logger is used for data acquisition, temporal store in battery backed 128K memory and transfer to PC through the direct links RS-232.
   Temperature and relative humidity sensors are integrated into the DataHog. Channels can be individually programmed with logging interval and gain to suit each sensor type. DataHog is battery operated with a choice of additional power supply solar and mains. DataHog is backbone of the weather station. It is an accurate and reliable multi-channel system with a choice of voltage, current or digital count inputs. It is easy to use, completely waterproof, robust, durable and low cost with no hidden extras, yet utilizes precision components and sensors. Ready configured on arrival. No complicated setup routines. Sensors just plug-in; no complicated wiring up. Extremely portability makes the MiniMet an ideal for short-term research or monitoring projects. MiniMet is supplied with SkyeLynx Standard, an easy-to-use communications, package for offloading data as a simple ASCII file.
   Our configuration: number of channals - 7, type of channals - differential, sample rate - 10 sec, interval of averaging - 5 min.
WIND VANE (Wind Direction) Accuracy: +/- 2% obtainable in steady winds over 5m/s
ANEMOMETER (Windspeed) Starting Speed (Threshold): 0.3m/s; Maximum Windspeed: Over 75m/s; Accuracy: +/- 2% + 0.1m/s
RELATIVE HUMIDITY Sensor type: Capacitive silica substrate, chrome alloy electrodes; Measurement range: 0-100% (at -20 to +70C); Resolution: 0.1%; Accuracy: 2% maximum, typical 1% or better
AIR TEMPERATURE Sensor type: Precision 10k thermistor (Fenwal) sealed to IP67. Low thermal mass; Measurement range: -20 to +70C; Resolution: 0.01C; Accuracy: 0.2 at 25C
AIR PRESSURE Range: 500mbar to 1050mbar; Resolution: better than 0.1mbar; Absolute error: at 20C and 1000 mbar typically 0.5mbar (maximum 1.0mbar); Error over: 0-50C, typically 1.5 mbar (maximum 3.6mbar)
PYRANOMETER Sensor: Silicon photocell, cosine corrected head; Spectral response: 400 - 1100 nm; Working range: 0-5000 W/m2; Linearity error: <0.2%; Cosine error: 3%; Azimuth error: <1%; Temperature coefficient: +/- 0.2 %/C; Longterm stability: +/- 2%; Temperature range: -30 to + 75C; Humidity range: 0-100% RH
UVB sensor Sensor: SiC Photodetector, cosine corrected head, specially formulated diffuser; Spectral response: 280 - 315 nm; Working range: 0-5 W/m2; Linearity error: better than 1%; Cosine error: 3%; Azimuth error: <1%; Temperature coefficient: +/- 0.2 %/C; Longterm stability: +/- 2%; Operating range: -30 to +60C, 0-100% RH
Sunphotometer Cimel CE-318 (Cimel Electronique, France)
Sunphotometer Cimel CE-318

   Sunphotometer consists of the sensor head, electronics box with microprocessor and store module, and robot. The sensor head of this instrument has 1.2° full angle field of view, two collimators with length of 33 cm for 10-5 stray light rejection and two silicon detectors for measurements of the direct sun and sky radiances.
   Eight ion assisted deposition interference filters are located in the filter wheel (in front of detectors) which is rotated by drive stepping motor. The sensor head is pointed by stepping azimuth and zenith motors with a precision of 0.05°. These pointing and solar tracking procedures are fulfilled by robot under the control of the microprocessor, which computes the position of the sun based on time, longitude and latitude coordinates of the site of observation.
   The accuracy of computation and directing of the sensor head is within approximately of 1° of the Sun. To track the Sun position more precisely four-quadrant detector built into the sensor head is used. Electronic box consists of two microprocessors for real time operation for data acquisition and motion control. Data from memory module of the sunphotometer can be transferred to a PC or via a Data Collection Systems, to one of the geostationary satellites: GOES, METEOSAT or GMS, and then retransmitted to the respective ground receiving station.
   Robot fulfills operations with the sun pointing and tracking. Sunphotometer Cimel CE-318 provides measurements of the direct solar radiance at 8 wavelengths in visible spectrum: 340, 380, 440, 500, 670, 870, 940 and 1020 nm; sky radiance in almucantar and in a solar principal plane at 4 wavelengths: 440, 670, 870 and 1020 nm. The channel at 940-nm is used to retrieve the precipitable water vapour content in atmosphere. The bandwidth of these interference filters is varied from 2 (UV channels) to 10 nm for visible and near-IR channels.
   The total uncertainty of spectral aerosol optical thickness measurements is varied from 0.01 to 0.02, and is spectrally dependent with high errors in the UV spectral range. Total water vapour content in the atmospheric column (in cm of precipitable water) is consistent to within ~ 10% of radiosonde or microwave radiometer measurements.

MICROTOPS II Ozonemeter (Solar Light Co., Inc., USA)
Microtops II Ozonometer

This instrument, equipped with the highest grade and long stability filters (with ion-beam assisted deposition) 305, 312, 320, 936 & 1020 nm, which embedded into a solid cast aluminum housing, assures accurate, stable optical alignment.
   MICROTOPS II is a hand-held device for simultaneous measuring of direct solar ultraviolet radiation at 3 discrete wavelengths within UV-B range and total columnar ozone content, accurately and dependably, and also for measuring total water vapor and aerosol optical thickness.
   MICROTOPS II has low noise electronics and 20 bit A/D converter to give an accuracy (< 2% for ozone) comparable to much larger and more expensive instruments; it has non-volatile memory, and can be connected to the PC through the RS232 port for data transfer, easy of use and portable, and has low cost.
   MICROTOPS II has built-in internal barometric pressure and temperature sensors that provide the information to compensate for Rayleigh scattering both for the ozone and aerosol optical depth measurements. An optional external GPS receiver facilitates field measurements. Ozone and total water vapor content calculation algorithms are programmed in the MICROTOPS II and the final results of all stored scans can be viewed on the LCD.
   The raw data are also stored in non-volatile memory to allow retrospective adjustment of algorithms. Each data point is annotated with date, time, site coordinates, solar angle, altitude, pressure and temperatures. By implementing the latest technology, instrument cost has been brought well below that of comparable ozonemeters, without sacrificing accuracy or features.