World Land Mapping with Sentinel-3

The last week we have advertised our new born project aiming to reach a global land and marine monitoring of the World with Sentinel-3. Indeed this mission offers a large dataset of geophysical data really usefull in the framework of the evaluation of climate change effects on Earth. In order to do that and thus to create time series images the first goal is to picture the entire Planet in a single image. To this end we have considered a monthly dataset of data, focusing on the August of the last year, to mosaic hundreds of cloudfree scene and finally get some unique images of the Earth. Of course the next step will be to show the monthly sequence of those data.

Chlorophyll Index

The first scene above shows the Chlorophyll Terrestrial Index acquired by the OLCI instrument, namely an important parameter in order to assess the health of the vegetation. It is dimensionless and the colour palette above spans from 0 (purple/red) to 6.5 (dar green). Greener regions have obviously a good health with reference to the other land parts, namely Indonesia, the central part of Africa, the North America region south to the Great Lakes and the eastern part of China. Deserts and arid regions are pictured in red/yellow or with no data at all being no vegetation. This distribution is similar to the one pictured below, the vegetation index. In the same way this index is dimensionless and shows the flora distribution all around the World. The colour palette scale spans from yellow (0) to dark green (1).

Global Vegetation Index

The image below pictures the Integrated Water Vapour for atmospheric column, expressed in kg.m-2. Water vapor is a critical component of Earth’s climate systems and allows to detect humid and arid regions over the World. As a global trend we can see that the higher values are near the equator and the water vapor is decreasing going to the poles. Very arid zones are the southern part of Africa and the South America western coast. Indeed those regions face extremely long period of drought and this is linked to a particular phenomenon involving sea currents from the Antarctica, aka the Humbold Current (see https://en.wikipedia.org/wiki/Humboldt_Current for a follow-up). This is obviously reflected in the vegetation and chlorofyll index too. The region appearing as one with the higher values of water vapour is the Republic of India. The Himalaya is a real shield between the central part of Asia and India and thus being of the greatest causes of the climate around India and Indochina and the Monsoon genesis. Indeed the dividing line is clear and we can easily distinct the mountain range.

Integrated Water Vapour Column

The next step will be to focus on marine data and so to health evaluation of our water biomasses.

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