Pacific Thorpex Vision Cliff Mass, UW

A Vision for THORPEX C. Mass, Univ. of WA Forecast Error

A Few Assumptions There are still significant initialization problems over the Pacific Ocean that have substantial negative impacts on forecast skill over and downstream of this body of water. Even with the current observing network, initializations and forecasts can be greatly enhanced by improving data assimilation approaches to make better use of the data (e.g., 4DVAR, EnKF, hybrid) Increasing remote-sensing assets (e.g., hyperspectral soundings, COSMIC data, lightning) will results in substantially improved prediction skill if we learn how to use them effectively.

A Few Assumptions The impact of additional in-situ data sources is not clear, given the context of the rapidly increasing remote sensing data. –If they are of value are they best applied in a targeting or surveillance mode or both? –To what degree are additional in-situ data needed to calibrate the remote sensing assets? –OSSEs are needed now to evaluate the value of proposed insitu platforms. We need a rational way to decide where data is need given the new remote sensing assets. –We can not afford to develop all of the proposed systems.

Assumptions To promote the maximum scientific creativity, THORPEX data assimilation research and experimental operations must not be limited to personnel at a handful of major centers. –Either resources at the major centers must become more open to academic and other researchers or data assimilation must become less centralized, as has been done for NWP. A comprehensive evaluation of quality of initializations and forecasts of major modeling systems is critically needed. To some degree we are flying blind and this needs to be remedied.

A Few Assumptions There are still major scientific and technical issues that should be examined as part of THORPEX. Some examples include: –The relationship of predictability to flow configuration. –The impact of tropical-extratropical transition on predictability. –Intelligent observing system design. A holistic view is needed to determine redundancies and deficiencies of the current and future observing systems, undoubtedly making use of OSSEs as a primary too. –University group, led by Jim Hansen and Steve Mullen, have a well-considered list of scientific issues.

A Few Assumptions Economical and flexible unmanned in situ observing systems (e.g., UAVs) should be developed and tested. –This is based on the unproven, but reasonable, assumption that insitu lower tropospheric data will be needed. Management and decision making for THORPEX should be made by a wide-ranging group that is not limited to operational centers and government agencies. Hard numbers for societal benefits are needed to make the case for Pacific THORPEX benefits.

The Pacific Predictability Experiment Several years of research and OSSEs/OSEs will lead to two multi-month experimental periods (winter and ) in which ideas will be tested. The experimental periods will demonstrate improved short and medium term predictability using approaches that are viable for operational application.

Details 2005, second half: Develop a specific plan including costs and potential sources of funding. Establish a scientific oversight committee with wide representation OSSEs and real-time data assimilation efforts evaluate the following issues, using the Pacific Ocean basin as the major testbed: –1. Evaluation of new data assimilation approaches such as EnKF, ETKF and 4DVAR applied to the current observational network to determine to what degree forecasts might be improved with some combination of the above data assimilation approaches.

Details –2. Evaluation of the impact of new remote sensing systems (hyperspectral soundings, more extensive use of cloud/water vapor winds, application of lightning data, application of the new COSMIC data sets, etc). This research will extend to the study of how such remote sensing data might be combined/thinned (superobs) or used in a targeted mode. –3. Evaluation of the benefit of new insitu observing systems (e.g., UAV, driftsondes, etc) or traditional manned aircraft within the context of current and future remote sensing systems. This task will include the evaluation of new insitu measurements in both targeted and surveillance modes. This evaluation should extend to evaluating increased deployment (or redeployment) of conventional observational platforms (e.g., buoys, radiosondes) or the additional of new observing capabilities to commercial aircraft or commercial container ships (e.g. ASAP).

Details : Engineering and testing of new insitu observing technologies : Basic science research as noted above First THORPEX Pacific Experimental Period (FTPEP). Real-time data assimilation and forecasts (0 to 7 days) will be run in parallel by several groups, testing the most promising approaches found during the previous two years. The forecasts will be verified in a uniform way both against each other and with operational data assimilation and prediction efforts. This experimental period will benefit from additional Arctic observations available during the polar IGY.

Details Analysis of the results of the First THORPEX Pacific Experimental Period. Further refinement of data assimilation approaches and insitu observations (if warranted). Continue research activities Second THORPEX Pacific Experimental Period, taking advantage of lessons learned during the first period and additional research in the intervening years. This period coincides with the Winter Olympics in Vancouver/Whistler, which should provide some additional resources for data gathering and verification.

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