MT validation

A key component of the Megha-Tropiques  project is the Validation  of the products and algorithms to ensure the highest quality. The validation plan has been designed in close link with the product developers in order to account for their specific need. The feedback loop from validation results to developers will be maintained throughout MT validation phase. The basis of validation is to compare  MT measurements with reference data acquired through dedicated campaigns or from operational networks, round the tropics thanks to international collaborations.


MT Ground validation Super site and gages networks in West Africa

The French led effort for the Ground Validation of rainfall products and water vapor products is focused on West-Africa ; Africa is indeed the greatest continental surface in the Tropics. A super site is set up in Ouagadougou, with a polarimetric radar to acquire the high-resolution rainfields and vertical profiles that are needed to validate the Instant rainfall products, and intense radio-sounding campaigns for the validation of water vapor products. Several densified raingages network provide a high quality ground reference for the accumulated rainfall products. Operational weather services or regional organization provide larger scale data from gages network or radio-sounding. The data is quality-controlled, and then validation products (including the necessary error bars) are produced for comparison with MT satellite measurements.

The Ouagadougou Super-site
The AMMA-CATCH densified networks
Regional scale


MT Aircraft/radar based Microphysics Validation Campaigns

An important source of uncertainty in the rain retrieval from microwave radiometric measurements arises from a lack of information on the characteristics of the icy hydrometeors. Over land in particular, the radiometric signal sensed by MADRAS will come essentially from the ice phase (85GHz and 157GHz channels) and the rainfall profile below will be deduced from it.  The radiometric signature of ice is related to both i) the density  number  of  particles ii) the ice density of the particles. Both need to be well parameterized in the radiative transfer model included in the BRAIN retrieval scheme.

To address this important issue two specific campaigns combining  aircraft based in situ information on the microphysics and radar observations have been organized. Both times the instrumented Falcone 20 from the French Airborne Environment Research Services (SAFIRE was mobilized for 4 weeks, allowing more than 10 scientific  flights. The campaigns  combine i) direct but punctual information from dedicated aircraft sensors and ii) longer time series and extended 3D coverage  provided by  polarimetric radar retrieval to extend the statistics.

The Niamey 2010 Campaign in Niger

The 2011 Dynamo campaign in the Indian Ocean


Other validation data sets and international collaborations

Important collaborative actions complement the French led MT GV dedicated sites and provide information from different eco-climatic zones. This is important to assess regional or rainfall regimes related bias in the products.



Darwin Australia Cpol radar data

The Meteo-France Outre-Mer radar data

Collaborations are also being set up with several weather services and atmospheric research centers throughout the Tropical band ; this site will be updated when they will be formalized.


The Precipitation Measuring Missions Ground Validation  meetings  (PMM GV ) and  validation activities in the framework of the International Precipitation Working Group IPWG ( offer great  opportunities and resources for discussing  validation issues, methodologies and to access reference data sets.


Who are we?

The french GV Team


More details

Please download the latest version of :

The extended validation plan for Rainfall products

The extended validation plan for Water Vapor products

The cal/val plan for the Instantaneous radiative flux at the Top of the Atmosphere