⑴ Ground radiation related theories
The formation of the climate on the earth is determined by the effect of solar radiation on the earth. About 51% of the solar radiation is absorbed by the surface of the earth, 19% is absorbed by the atmosphere and clouds, and about 30% is directly reflected back by the ground, atmosphere, and clouds. The solar radiation heat absorbed by the surface and the atmosphere is mainly It is emitted back to space in the form of long-wave radiation. It is through the absorption of solar radiation from the earth’s surface and the long-wave radiation from the earth’s surface to space that the thermal balance of the earth’s surface can be maintained, and the long-term and stable climatic conditions suitable for human survival unique to the earth can be maintained.
Outdoor climate factors related to the built environment, including solar radiation, atmospheric pressure, wind, air temperature, and air humidity, are all determined by solar radiation and the physical conditions of the earth itself.
The working principle of the pyrometer is the thermoelectric effect principle, that is, the hot node is on the sensing surface, the cold node is located in the body, the cold and hot nodes generate thermoelectric force, and the output signal is proportional to the solar irradiance in the linear range, in order to reduce the temperature For influence, use a two-layer glass cover (such as a total pyranometer), or to prevent the influence of wind, use a polyethylene film cover (such as a net radiant meter).
⑵Equipment composition
In addition to the equipment shown in Figure 1, the system configuration of the PC-2-T solar radiation standard observation station should also include an empty box barometer, glass
Glass tube liquid thermometer, hot bulb anemometer and manual ventilation dry and wet bulb thermometer, etc.
⑶Introduction to Solar Radiation Standard Observation Station
As the test host, the recorder is connected to various radiation sensors through the communication line to observe and record the total radiation of the sun (total pyrometer, first channel), net radiation (net pyrometer, second channel), and direct radiation (direct radiation) Meter, third channel), reflected radiation (reflective radiometer, fourth channel) and scattered radiation (scattered radiometer, fifth channel) and other radiation quantities. The recorder is easy to operate, has high test accuracy, strong anti-interference ability, and can be used for both AC and DC. Note: Be sure to turn off the recorder when plugging or unplugging the communication line.
⑷Display content of recorder
Each channel displays the instantaneous radiation value E (unit: W/m2), the hourly maximum value∩ (unit: W/m2), the hourly cumulative amount H (unit: MJ/m2), and the daily maximum value U (unit: W /m2) and the daily cumulative amount d (unit MJ/m2).
⑸The installation and installation points of the radiation meter
Ensure that the sensing surface of the pyranometer is 1.5m above the ground, so that the horizontal bubble is in a horizontal position, and the output cable of the meter is connected to the input end of the recorder for measurement.
①Total pyranometer TBQ1, reflection pyranometer TBQ2 The total pyranometer is used to measure the total radiant intensity (W/m2) of direct sunlight and sky scattering received by the sun with a wavelength of 0.3-3μm within a solid angle of 2π on a horizontal surface.
The reflective radiometer, that is, the total radiation sensor, is equipped with a dedicated connecting rod, with the sensing surface facing down, to measure short-wave reflected radiation of 0.3-3μm.
Install in an open place around, there are no obstacles on the sensing surface, the glass cover should be kept clean, the desiccant should be replaced regularly, and the output cable plug should be in the north.
②The net pyranometer TBBI is the difference between the full-band radiation projected downwards from the sky (including the sun and atmosphere) and upwards projected from the earth’s surface (including soil, plants and water surface). It is the main data for studying the status of the earth’s heat budget.
The measuring range is 0.27 ~ 3μm shortwave radiation and 3 ~ 50μm earth radiation.
Install in an open place around, there are no obstacles on the sensing surface, the film cover should be kept clean, the desiccant should be replaced regularly, and the output cable plug can be connected to the input end of the recorder.
③The direct radiation meter TBS2 measures the vertical solar surface (viewing angle of about 0.5°) radiation and the scattered radiation of the narrow annular sky around the sun.
Measure the amount of direct solar radiation in the spectral range of 0.3 ~ 3μum.
④Scattering radiometer TBD1 total radiation sensor is equipped with a light-shielding ring device, that is, the scattered radiation or sky radiation is measured after shielding the direct part of the sun.
The light-shielding ring has a width of 65mm and a diameter of 400mm. It is fixed on the adjustment screw on the ruler. The ruler has latitude, longitude and declination scales.
The edge of the chassis is aligned with the north-south direction, so that the gauge of the instrument points to the north-south (shading ring screw adjustment knob handle is facing north), and the scale is fixed according to the latitude of the location. The total pyrometer is installed horizontally on the platform in the shading ring so that the output plug faces north. The blackened sensing surface of the pyranometer should be located at the center of the light shielding ring, and the light shielding ring should be adjusted to the corresponding position according to the sun’s declination of the day, so that it just completely covers the sensing surface and glass cover of the meter.
⑹Measure and record
After the instrument is installed, it is necessary to prepare the original data record table, please record several times until the data in the table is completely recorded, and the unit is required