(1)The sun/sky radiometer (CE318-NE/DP)
The automatic sun/sky radiometer (CE318) is an instrument used to measure sun and sky radiances, which is used to get the sun and sky radiance of different wavelength in UV, VISR and NIR, different direction and different time to calculate the characters of atmospheric aerosol, moisture and ozone. This instrument has many features: higher precision, mature technology, a wide range of applications for atmospheric environmental monitoring, calibration of satellite products and so on. Furthermore, the radiometer is the main instrument of SONET, AERONET, and others observational network with a series of advantages: flexible and portable, automatic observation and transformation of data.
The automatic sun/sky radiometer is composed of optical sensor, biaxial stepping motor system, control box and accessory. The optical sensor is made of light shaft and optical head. The light shaft is a binocular sight which is used to filter the stray light of the sky. The optical head is equipped with quadrant, optical element and photoelectric detectors. The quadrant is in accordance with distribution of direct solar radiation intensity in four quadrants and displacement to receive the position of the radiation intensity maximum and follow the sun precisely. Biaxial stepping motor system is the mechanical transmission of sun/sky radiometer which can make rotation in zenith direction and azimuth direction. Control box is used to control the model of instrument observation, parameter setting, and automatic data recording and so on. The accessory includes exothermal battery connection, locking course, data transmission line, solar panel, humidity receptor.
SONET mainly adopts CE318-DP, which has 10 spectral channels: 340nm, 380nm, 440nm, 500nm, 675nm, 870nm, 936nm, 1020nm, 1020i and 1640 nm, and 936nm is among the range of vapor in the air absorption.
Figure 1. the sun/sky radiometer (CE318-NE/DP)
(2)Hand-held sun photometer (Microtops)
MICROTOPS II is an hand-held sun photometer used to achieve accurate measurements of optical thickness. It can measure and storage direct solar radiation of 5 discrete wavelengths. Through one algorithm, it could get optical thickness. A complete hand-held sun photometer includes Microtops sun photometer, GPS receiver, tripod, data transmission line (as shown in figure below). The instrument has several features: portable and getting the real-time result of AOD. The band width: 10nm; FOV: 2.5°; Precision: 1%~2%; the resolution of solar radiation: 0.01w/m2; weight: 600g; equipped with 4*AA alkaline cells.
Figure 2. Hand-held sun photometer
(3) CO2 sun photometer (CE318-CO2)
CO2 sun photometer could observe the solar radiation intensity of land surface and acquire the information of CO2 content, based on the absorption of the sun light by CO2 molecules. CO2 sun photometer is the same as ordinary CE318. including four parts: optical sensor that used to locate the sun accurately and receive the solar radiation and convert it to output electrical signal; Biaxial mechanical transmission parts which can make optical head rotate in the horizontal and vertical direction and trace solar in real time; control box in charge of system setting, operation and data logging; other units which includes storage battery (supply energy for mechanical parts rotating and control box running), solar panel (supply power for field observation), and hygrometer (if rain, the instrument would be stopped).
The 14 narrow channels in SWIR of CO2 sun photometer achieve the column burden of CO2. Photoelectric transducer transform the sun’s rays signal to the exportable voltage signal and record it in the corresponding storage unit.
Figure 3. CO2 sun photometer (CE318-CO2)
