Sunday February 28, 2021

Satellite helps to monitor natural phenomena, environmental changes

Published : 25 Jul 2020, 02:07

  DF Report

The Sentinel-2 satellites of the European Union and the European Space Agency pass over Finland daily, taking pictures of the surface on a 290-kilometerwide swath. Press Release Photo by ESA/ATG medialab.

The Finnish Environment Institute (SYKE) monitors the state of the environment with the help of satellite technology and is a European forerunner in the efficient use of satellites, said a press release of SYKE on Friday.

The TARKKA service, which contains plenty of open data, can be accessed by anyone who wants to check on various natural phenomena and environmental changes.

“True colour images based on satellite data show astonishing details, ranging from algal rafts and ships to waves and foam on waves breaking in storms, as well as the structure of ice and passages formed therein by vessels traveling in the sea,” said SYKE researcher Sakari Väkevä.

Satellite remote sensing is based on the measurement of sunlight reflected from land or water, or the thermal radiation emitted by the Earth. The orbits of satellites, 500 – 1000 kilometres above the surface of the Earth, have been synchronised with the movements of the sun in such a way that they all pass over the areas that they are imaging in all places at the same time of the day, usually about noon.

The most important satellites used by SYKE are the Sentinels (Sentinel-2A/B, Sentinel-3A/B) that are part of the Copernicus programme of the European Union and the European Space Agency (ESA), and the Landsat-8 of the United States Geological Survey (USGS). In addition, NASA's Modis Terra satellite is used for monitoring the ice cover on lakes and the fractional snow cover on land.

The satellite images are processed at the Sodankylä National Satellite Data Centre in northern Finland, whose main Finnish users are SYKE and the Finnish Meteorological Institute.

The Centre is part of the Copernicus Sentinel Collaborative Ground Segment, which makes the first observed data available usually a few hours after the overpass of a satellite.

The centre uses the Calvalus computer cluster for the processing of large volumes of satellite material. In the early hours of the morning the system uses observational data from satellites to derive observables describing water quality, such as turbidity, Secchi disk transparency, chlorophyll concentration, and humus absorption.