Solar radiation research

Solar energy, distributed across the electromagnetic spectrum, warms the Earth, causes weather, and makes plant and animal life possible. At the remote sensing group the focus lies on modelling solar radiation in the range between 250 and 4600 nm. This leaves out a major part of the infra-red radiation, whose waves are much lower-frequency and transmit much of the heat from the sun.

The most harmful ultraviolet (UV) rays (wavelengths below 280 nm) are almost completely absorbed by Earth’s atmosphere. Less powerful UV radiation travel through the atmosphere, and can cause sunburn (Erythmea). Almost all life on Earth relies on solar energy for food. Sunlight can be absorbed and converted into nutrients through photosynthesis. This part of the spectrum (400 - 700 nm) is known as photosynthetically active radiation (PAR)

Back in the 1990's people at the remote sensing group developed a system for analysis of solar radiation in North-western Europe. The work was funded by SMHI together with the Swedish environmental and radiation protection agencies. The model system, known as STRÅNG (Swedish acronym for "RADiation using the ÅNGström model"), has been operational since 1999 and maps hourly radiation in near real time. Output from STRÅNG is used for a number of purposes, e.g. to follow up some of Sweden's environmental objectives, estimating potential solar energy production and modelling photosynthetically dependent processes on land and in the water.

Some examples of ongoing solar radiation research:

- STRÅNG development; adaptation and improvement of the SMHI operational radiation model system STRÅNG. The objective of the project is twofold. First the STRÅNG system needs to be adapted to the region and output of the new operational numerical weather prediction model, second the model should be improved in a number of areas (e.g. albedo, aerosols, inconsistency between global and direct radiation).

- DNICast; Direct Normal Irradiance Nowcasting methods for optimized operation of concentrating solar technologies. The objective of the project is to provide operators of power plants using concentrating solar technologies (CST) with reliable forecasts of the direct normal irradiance (DNI).

- Improved evaluation of solar electricity production for increased investments in PV technology. The project goal is to increase the investments in PV technology by describing how data of solar irradiance and temperature can be processed to generate accurate evaluations of forecasted solar electricity generation in Sweden.