RESEARCH OPPORTUNITIES FROM EMERGING ATMOSPHERIC OBSERVING AND MODELING CAPABILITIES

The Second Prospectus Development Team (PDT-2) of the U.S. Weather Res earch Program was charged with identifying research opportunities that are best matched to emerging operational and experimental measurement and modeling methods. The overarching recommendation of PDT-2 is that inputs for weather forecast models can best be obtained through the u se of composite observing systems together with adaptive (or targeted) observing strategies employing both in situ and remote sensing. Optim al observing systems and strategies are best determined through a thre e-part process: observing system simulation experiments, pilot field m easurement programs, and model-assisted data sensitivity experiments. Furthermore, the mesoscale research community needs easy and timely ac cess to the new operational and research datasets in a form that can r eadily be reformatted into existing software packages for analysis and display. The value of these data is diminished to the extent that the y remain inaccessible. The composite observing system of the future mu st combine synoptic observations, routine mobile observations, and tar geted observations, as the current or forecast situation dictates. Hig h costs demand fuller exploitation of commercial aircraft, meteorologi cal and navigation [Global Positioning System (GPS)] satellites, and D oppler radar. Single observing systems must be assessed in the context of a composite system that provides complementary information. Mainte nance of the current North American rawinsonde network is critical for progress in both research-oriented and operational weather forecastin g. Adaptive sampling strategies are designed to improve large-scale an d regional weather prediction but they will also improve diagnosis and prediction of flash flooding, air pollution, forest fire management, and other environmental emergencies. Adaptive measurements can be made by piloted or unpiloted aircraft. Rawinsondes can be launched and sat ellites can be programmed to make adaptive observations at special tim es or in specific regions. PDT-2 specifically recommends the following forms of data gathering: a pilot field and modeling study should be d esigned and executed to assess the benefit of adaptive observations ov er the eastern Pacific for mesoscale forecasts over the contiguous Uni ted States; studies should be done over the western Atlantic and Carib bean-Gulf of Mexico regions, particularly during hurricane season; and enhanced observations should be implemented for the mountainous weste rn states and for the Mississippi and Missouri River Valleys. Data sen sitivity tests and observing system simulation experiments (OSSEs) are important tools for gauging the benefit of existing or proposed obser ving systems. OSSEs involve only model predictions and are essentially self-contained. Data sensitivity tests require the full consideration of modeling infrastructure, namely, observation ingest quality contro l, objective analysis, and numerical prediction. Sensitivity tests inv olving both wind and moisture profiles are particularly needed to dete rmine their impact on improved precipitation forecasts. New variationa l analysis techniques are capable of assimilating so-called proxy obse rvations. These techniques should be fully exploited. Diabatic initial ization should be addressed through the assimilation of satellite clou d data and very high resolution WSR-88D radar measurements into very h igh resolution models with sophisticated cloud microphysics. Success i n this area should improve quantitative precipitation forecasts in the first few (model) hours. There is a pressing need to better understan d the interaction of moist convection with large-scale flow. One key i s better characterization of the impact of precipitation formation and evaporation on the fluxes of mass, momentum, and heat in moist convec tion. Humidity measurement in precipitating downdrafts is a crucial me asurement, which currently cannot be made reliably. The capabilities o f polarization-diversity radar should be explored in a quasi-operation al context to determine whether WSR-88D radars should be upgraded. Pro gress in quantitative precipitation forecasting is impeded by poorly r esolved and inaccurate water vapor measurements. Further improvements in numerical weather prediction demand improved monitoring of Earth su rface characteristics so that spatial and temporal variations in air-s urface fluxes are realistically simulated. Over land, priority should be given to the coupling of mesoscale meteorological models with hydro logical models and to routine assimilation of surface (soil, moisture, and plant) characteristics. Improved air-sea fluxes are essential to proper modeling of marine cyclogenesis. The most important, practical ocean measurements include sea surface temperature, thermocline depth, wave spectra, and ice coverage and thickness.