Foresight in sight

Nihon Unisys

About "Sky Radiation Simulator"

About "Sky Radiation Simulator"

We are conducting technological research on "Sky Radiation Simulator" that simulates the sun's rays looking up from the ground. This technological research is conducted for each wavelength of solar ultraviolet rays related to deterioration of structures and human health, visible solar rays related to plant growth and landscape, and solar infrared rays related to heat. The energy intensity and integrated value are calculated according to the date and time, the place, and the irradiation direction.
For example, you can quantify and visualize the sun's rays, such as calculating the hourly insolation intensity of a location by wavelength band or drawing an image of a sky map.
Quantify and visualize the sun's rays
Fig.1 Quantify and visualize the sun's rays

Features of "Sky Radiation Simulator"

  • Anytime
    You can specify the year, month, day, hour, minute, and second.
  • Anywhere
    Using the world's atmospheric observation data, it is possible to specify the location without limiting the area. You can also specify the altitude.
  • Any direction
    Direction and elevation / depression angle can be specified.
  • Any wavelength
    You can specify UV, visible, infrared, or your own wavelength band and specify the step size of the calculation in 1 nm increments.
  • High accuracy
    The current calculation accuracy is about 85%, but we are working to further improve the accuracy.
  • Patent pending
Features of
Fig.2 Features of "Sky Radiation Simulator"

Light scattering model by the atmosphere

Daylight is classified as a light source and can be divided into direct light, scattered light, and reflected light.
In the “Sky Radiation Simulator”, after calculating the sun altitude from the specified latitude, longitude, and date and time, the radiation transfer equation is used for the scattering / absorption phenomenon in the atmosphere, with the spectral distribution obtained by separating the sun rays at the upper end of the atmosphere for each wavelength as the initial value. By solving, the energy intensity of the sun's rays (ultraviolet rays, visible rays, infrared rays) that reach the ground is calculated.
Light scattering model by the atmosphere
Fig.3 Light scattering model by the atmosphere
Since direct light and scattered light can be calculated in this way, reflected light can also be calculated using the energy intensity of direct light and scattered light by modeling the ground or ground objects. In addition, by using the cloud cover prediction and/or actual data together with the "Sky Radiation Simulator", a more accurate model can be constructed, and highly accurate calculations become possible.

Utilization image of “Sky Radiation Simulator”

By using "Sky Radiation Simulator", it is possible to perform precise simulations by modeling physical phenomena related to sunlight with mathematical formulas. For example, calculation of the degree of influence of ultraviolet rays on the human body, prediction of deterioration of paint and material, prediction of effect of heat-shielding paint, prediction of temperature of solid, liquid, soil, and human body, prediction of solar power generation, prediction of growth of plants, it is a time series simulation such as.
Utilization image of
Fig.4 Utilization image of "Sky Radiation Simulator"