While conventional surface-based measuremeñts have, in some cases, a long historical record, they are horizontally sparse; this is particularly true in the Southern Hemisphere and over the oceans. Upper air measurements of even the basic variables of temperature and humidity are even rarer. The only practical way of monitoring the current climate and its variability is via satellite observations coupled with numerical climate models. However, neither of these two systems are currently well validated in the areas of clouds and precipitation, which are two critical components in the Earth's radiative and water cycle budgets. The CLOREVAL project will provide such validations, on a regional basis, so that we may confidently apply the same satellite and modelling techniques globally.
The primary aims of this proposal are:
a) To verify, and potentially improve, the radiative transfer models used to retrieve various meteorological and oceanographic parameters from current and future microwave sensors, including SSM/I, SSM/T-2, ATSR/M, AMSU-A/B and MIMR, and thence
b) to validate estimates of liquid water path (LWP) derived from the Special Sensor Microwave Imager (SSM/I) on the US Defense Meteorological Satellite series and from other satellite-borne microwave instruments. in order to provide the optimum quality global LWP and other products for climate studies and for use within operational weather forecasting under all meteorological conditions.
These objectives will be addressed by obtaining in-situ data, mainly coincident in space and time with the SSM/I swaths, e.g. with airborne cloud sensors and microwave radiometers, during a series of short campaigns dedicated to the SSM/I instrument over sea (e.g. the Northern and Sub-Tropical Atlantic) during 1996-7. A wide variety of cases need to be sampled, including precipitating and non-precipitating clouds.
Following this data gathering phase, the aircraft, satellite and ground-based instrument data will be analysed by the participants using existing techniques. The results of this analysis will address the above objectives, and will be made freely available.
Funding SchemeCSC - Cost-sharing contracts
78140 Velizy Villacoublay
BS8 1SS Bristol