Eleven Years of Earth’s Skin Temperature from IASI
Résumé
While long-term temperature time series mostly rely on weather stations, only satellite data are able to providesystematic global temperature data, from pole to pole on a regular basis, over both land and sea. Satellitesmeasure the “skin” temperature derived from upwelling radiation at the Earth’s land surface. The evolution of skintemperature is not yet fully exploited as its measurement is fairly recent.One of the IASI-Flux and Temperature ERC project tasks aims at providing new climate benchmarks byusing skin temperature observations from the calibrated radiances measured twice a day at any location by theIASI thermal infrared instrument on the suite of Metop satellites (2006-2025). The uniqueness of this project isthat the IASI-data record will be completely independent from third party information, with no other data fromobservations or models used, and can therefore serve as an independent reference to e.g. reanalysis, or otherclimate data records.In this presentation, we first describe our iterative method based on entropy reduction combined with artifi-cial neural networks to derive an independent record of IASI temperature, we next compare and validate our novelmethod with different datasets (e.g. EUMETSAT, ECMWF reanalysis, SEVIRI satellite products and groundmeasurements). We then show our results of global skin temperature over land and sea and in different regionsin the world over the period [2008- present]. The observed trends are analyzed at seasonal and regional scales inorder to disentangle natural (weather/dynamical) variability and human-induced climate forcing. Finally, we showhow expanding cities are hotspots for skin temperature reflecting the usefulness of skin temperature as a tracer forhuman-induced land use and climate change