Presentation on theme: "INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION Ben Maathuis Department of Water Resources ITC-Enschede The Netherlands From."— Presentation transcript:
INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION Ben Maathuis Department of Water Resources ITC-Enschede The Netherlands From Cloud Top Temperature to Rainfall; Blending MSG and TRMM
From temperature to rainfall (1) Use TRMM to calibrate Meteosat Cloud Top Temperature (10.8 micron band) and transform a time series of MSG images into Precipitation.
View TRMM data using Orbit Viewer and select area, export data to lat/long/rainfall intensity table From temperature to rainfall (2) Available from http://tsdis.gsfc.nasa.gov
Import time series of MSG data using the MSG Data Retriever, converted to TOA Temperature From temperature to rainfall (3) Some Key-features: Based on open source GDAL drivers; Fully controlled geometry & radiometry, conversions to diff. data formats: DN, radiances, reflectance, temperature; Diff. user defined output formats and resolutions (interpolation); Easy date/time range selection and series construction.
Import of tabular TRMM observations, linking the point map and corresponding MSG image using ILWIS Large number of TRMM rainfall observations From temperature to rainfall (4)
Low correlation due to spatial and temporal offsets when aligning geostationary IR and LEO PMW datasets on a per-pixel basis; Improvement of correlation by averaging procedure. From temperature to rainfall (5) After: “Validation of an operational global precipitation analysis at short time scales”. By: F. Joseph Turk, et al Marine Meteorology Division, Naval Research Laboratory, Monterey, California 93943
TRMM rainfall pixels are averaged based on MSG–IR temperature class intervals (in classes of 0.5 or 1 degree K) to obtain for a temperature range (e.g. from 180 to 260 Kelvin) for each temperature class the average corresponding rainfall intensity From temperature to rainfall (6)
Develop an improved relationship between averaged rainfall intensity and temperature From temperature to rainfall (7)
Transform temperature time series to rainfall by single statement From temperature to rainfall (8) rain08sept:=maplistapplic(t_2005 09080000_ir_108.mpl, "iff((##)<260,4.3505278e- 005*(exp(2550.0127/(##))),0)") Can also be displayed as animation
Rainfall per time step Accumulated 24 hour rainfall From temperature to rainfall (9)
TRMM observations can be used for MSG-IR calibration after an averaging procedure but needs better cloud mask and type determination; For validation synoptic station data has to be used (at appropriate temporal resolution -> tipping bucket); Low cost ground receiving station and free software sources make such a near real-time system suitable for e.g. National Hydrological Services and Basin Authorities; Especially suitable for short duration rainfall events, e.g. for flash floods. Conclusion