SEASONAL SNOW COVER EXTENT FROM MICROWAVE REMOTE SENSING DATA: COMPARISON WITH EXISTING GROUND AND SATELLITE BASED MEASUREMENTS
A significant response of global warming is expected to occur over the high latitudes. Due to the presence of permafrost and snow cover these regions are very sensitive to an increase in air tem-perature. Our objective is to derive a daily Snow Cover Extent variation from satellite microwave sensors...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.460.1461 http://las.physik.uni-oldenburg.de/eProceedings/vol04_2/04_2_mialon1.pdf |
| Summary: | A significant response of global warming is expected to occur over the high latitudes. Due to the presence of permafrost and snow cover these regions are very sensitive to an increase in air tem-perature. Our objective is to derive a daily Snow Cover Extent variation from satellite microwave sensors over Canada-Alaska and Northern Eurasia (latitudes>50°N), as in situ measurements do not allow a study over northern high latitudes. Passive microwave data from SSMI (Special Sensor Microwave Imager) sensors are adequate for this study as they can measure the energy emitted by the earth surface, independent of solar illumination and cloud cover. Here, we are presenting a simple method based on vertically polarized brightness temperatures at 19 and 37 GHz and the determination of an adaptative threshold. The study of the 1988-2002 mean seasonal snow extent shows a maximum snow cover for mid-February of (9.69+/-0.06)·106 km2, for the Canada/Alaska area, and of (20.75+/-0.32)·106 km2 over Northern Eurasia. We compare the seasonal variation with two existing satellite datasets: one from the NSIDC (National Snow and Ice Data Center, Boulder, USA) derived from optical sensors, and one from IMS (Interactive Multisensor Snow and Ice Mapping System) derived from different sen- |
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