Results of numerical simulations of the hurricane Bret (1999) obtained with the non-hydrostatic model meso-NH (LA & CNRM, France) were used to compute the brightness temperatures at the frequencies of the TRMM Microwave Imager (10H-V, 19H-V, 21V, 37H-V, 85H-V GHz).

For the simulation of these brightness temperatures we used a simple plan-parallel radiative transfer model based on Eddington 2nd approximation. The results obtained will be discussed in terms of comparisons with the actual observations made by the TMI, interpreting the differences as a signature for the representativeness of the microphysics parameterisation of meso-NH. The presented results are obtained for the 21st of August overpass of Bret by the TRMM satellite. The hurricane was experiencing intensification while approaching the coasts of Texas.

In this study, we used Yanai's (1973) approach to compute average Q₁ (Apparent Heating) and Q₂ (Apparent Moisture Sink) within different rings centred on the hurricane’s eye from 0.5 to 18 km altitude. The approach proposed by Yang and Smith (2000) is also used for comparison. Different snapshots of the Bret’s model simulation are used to calculate Q₁(t) and Q₂(t) in order to study the link that might exists with the hurricane evolution.