GCSS/ISCCP CLOUD REGIME ANALYSIS POINTS THE WAY FOR GCM MODEL IMPROVEMENT (Page 6) BSRN LONGWAVE DOWNWARD RADIATION MEASUREMENTS SHOW PROMISE FOR GREENHOUSE DETECTION STUDIES LBA SHOWS IMPACT OF AEROSOLS ON CLOUDS

Evolution of the concentration of aerosols with a diameter less than 10 µm (PM 10) measured in central Rondônia in a pasture site during September to No-vember 2002. The arrows indicate the first significant rainfall on October 7 and the onset of regular rainfall in the beginning of November. Data from LBA/Smoke, Aerosols, Clouds, Rainfall and Climate (SMOCC) Project. See article on page 4. Ratio between the GCM-projected global annual mean change signal in a transient GCM experiment (Roeckner et al., 1999) and the interannual variability in terms of standard deviations in an unperturbed control run ("sig-nal-to-noise ratio") for longwave downward radiation (solid line) and surface temperature (dotted line). See article on page 9. Since its inception GEWEX has had close ties with a number of national meteorological centers, such as the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Prediction (NCEP), the Japanese Meteorological Agency (JMA), and the European Center for Medium-Range Weather Forecasts (ECMWF). These ties have been mutually beneficial as these centers have provided guidance to GEWEX research and they have benefitted from GEWEX results. However, with few exceptions, progress in developing a similar rapport with national hydrologic services has been slower. GEWEX has expended considerable effort on research that could benefit hydrological forecast services. GEWEX efforts, such as the Global Soil Wetness Project (GSWP) and regional hydrologic modeling projects launched in the Continental Scale Experiments (CSE) have provided a basis for regional hydrologic applications. These efforts have benefited numerical weather prediction systems because the hydrological understanding has led to improved land surface schemes. However, their benefits to hydrologic services have been more limited. GEWEX is exploring strategies for working more closely with hydrologic services through the Water Resources Application Project (WRAP) and the Hydrology Ensemble Prediction Experiment (HEPEX). One complexity in dealing with operational hy-drologic services is the absence of common approaches between the national services, or, even regional branches of the same service. In some countries the national services do not have strong ties to the meteorological services, the hydrologic services are limited and the techniques used are quite empirical in nature. These differences make it difficult for a program like GEWEX, which fo-cuses on large scale hydrologic models, to develop linkages across all the wide-ranging needs of hydro-logic services worldwide. For a number of years, the GEWEX Americas Prediction Project (GAPP) has been funding a core project in the NOAA hydrologic services …