The net radiation sensor is used to measure the exchange of radiation energy between the earth's surface and the atmosphere. Its data range covers two key bands: shortwave radiation and longwave radiation, as follows:1、 Shortwave radiation data range
spectral range
Shortwave radiation mainly comes from the sun, with a spectral range of 0.3-3 micrometers (300nm-3000nm), accounting for about 99.5% of the total energy of solar radiation. This band includes the ultraviolet, visible, and near-infrared regions, and is the main source of surface energy input.
measurement range
Typical value: The shortwave radiation measurement range of most net radiation sensors is 0-2000W/m ², which can cover the solar radiation intensity under different weather conditions such as sunny and cloudy days.
Extreme values: In areas with strong sunlight such as plateaus and deserts, shortwave radiation may briefly exceed 2000W/m ², but sensors typically ensure data accuracy through redundant design or calibration algorithms.
Application scenarios
Shortwave radiation data is used to calculate surface reflectance, solar radiation potential (such as photovoltaic power plant evaluation), and vegetation photosynthetically active radiation (PAR), and is a key parameter in agriculture, meteorology, and energy fields.
2、 Range of longwave radiation data
spectral range
Long wave radiation is emitted from the surface and atmosphere, with a spectral range of 3-100 micrometers (3000nm-10000nm), and is closely related to the temperature of objects. The surface releases energy to the atmosphere through longwave radiation, while greenhouse gases such as water vapor and carbon dioxide in the atmosphere return energy to the surface through longwave radiation.
measurement range
Typical value: The measurement range of longwave radiation is usually -200 to 200W/m ². Negative values indicate that the longwave radiation emitted from the Earth's surface is greater than the radiation returned by the atmosphere (such as nighttime surface cooling), while positive values indicate stronger atmospheric inverse radiation (such as when cloud cover is present).
Extreme values: In extremely cold or hot environments, long wave radiation may exceed this range, but sensors correct errors through temperature compensation algorithms (such as built-in platinum resistance temperature sensors) to ensure data stability.
Application scenarios
Long wave radiation data is used to analyze surface energy balance, greenhouse effect intensity, and urban heat island effect, and is an important basis for climate research, ecological monitoring, and building thermal design.
3、 Net radiation data range
Net radiation is the algebraic sum of shortwave radiation and longwave radiation, and its data range is determined by the following formula:
Net radiation=(incident shortwave - reflected shortwave)+(downward longwave - upward longwave)
Typical value: The measurement range of net radiation is usually -300 to+2000W/m ², depending on the surface type, weather conditions, and diurnal variations.
During the day: The solar radiation is strong, and the net radiation is usually positive, indicating that the energy absorbed by the surface is greater than the energy released.
At night: there is no solar radiation, and the net radiation is usually negative, indicating that the surface releases energy into the atmosphere through longwave radiation.
Extreme values: In special environments such as plateau permafrost and deserts, net radiation may exceed typical ranges due to high or low surface albedo, but sensors ensure data integrity through high-precision thermopile detectors and multi-layer coated optical systems.
4、 The impact of sensor design on data range
Detector type: The dual channel thermopile detector can measure short wave and long wave radiation separately, covering the full spectral range (0.3-50 μ m or wider), avoiding the spectral truncation error of traditional single channel sensors.
Temperature compensation: Built in temperature sensors (such as platinum resistors) monitor the temperature of the detector in real time, and correct the impact of temperature drift on measurement accuracy through software algorithms to ensure stable operation in an environment of -40 ℃ to+70 ℃.
Protective design: The hemispherical polyethylene film cover or silicon cover can prevent wind, rain, and dust interference, reducing the impact of environmental factors on the data range.