1224 
A study showed how PBMR data could be used to map soil moisture variations (Mahantango 
watershed-Pennsylvama) for use in a spatially distributed hydrologic model. [A similar approach was depicted in 
Moran's talk]. 
Finally, several presentations were devoted to field measurements campaigns aimed at refining our 
understanding / modelling of surface characteristics. The extensive work performed on snow (1-90 GHz) at the 
university of Bon was presented as well as work related to the PORTOS experiment in Avignon. The latter were 
mainly focused on surface roughness / moisture profiles / vegetation influence on the microwave signal at 
frequencies ranging mainl y from 1.4 to 10 GHz. Also presented was the work done by the Florence group on the 
relative influence of plant constituents on the microwave emission. 
Most of the studies presented showed that extensive and good quality data sets are being collected 
main ly for modelling and validation purposes 
3 - MODELLING 
Even though modelling results ware presented in almost all the presentations it seemed that two could be singled 
out since they were completely "modelling oriented". 
A review paper was given on direct modelling approaches and model invasion in passive microwaves. 
It gave an overview of the state of the art, the most pro mi zing avenues by aiming at a dual approach (discrete + 
continuous approaches). Also of intaest, a presentation whae -for the first to our knowledge- a microwave 
emission model has been coupled to a vegetation growth model. Such approaches are innovative and worth 
furtha consideration 
4 - CONCLUSION 
A severe gap was noted during this session. The retrieval of atmospheric parameters (except for rain) ova land 
was not covered, partially due to the withdrawal of one papa from the plenary session. 
Apart from this all the fields are covaed with a stress on vegetation charactaisties. The modelling 
activities are quite healthy with significant efforts devoted to the simplification of sophisticated models. We felt 
also that the work on surface temperature retrieval and coupling passive microwaves with aop or hydrologic 
models is very promizing and should be encouraged. 
From the results gained in instrumentation, we believe that more should be allotted to materialize the 
"ESTAR" concept as synagistic with classical concepts (SSM/I - MIMR) for soil moisture retrieval. The 
PORTOS instrument should prove to be an ideal tool for developing algorithms for MIMR and should be widely 
used. 
Finally, we believe that passive miaowaves are probably best suited to get direct measurements of 
surface parameters such as soil moisture. We should thus strive to validate robust algorithms to retrieve useful 
geophysical parameters from remotely sensed passive microwave data.