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Session 1 – summary (1). Several new satellite data types have started to be assimilated in the last 4 years, all with positive impacts, including Metop-B (in addition to Metop-A) CrIS and ATMS on Suomi-NPP MW sounder in low-inclination orbit (Megha-Tropiques/SAPHIR)
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Session 1 – summary (1) • Several new satellite data types have started to be assimilated in the last 4 years, all with positive impacts, including • Metop-B (in addition to Metop-A) • CrIS and ATMS on Suomi-NPP • MW sounder in low-inclination orbit (Megha-Tropiques/SAPHIR) • ISS Rapidscat – impact on TC track forecasts • MWHS-2 183 and 118 GHz channels • AMSR-2 • In general, little evidence of “redundancy” or “saturation”. • Assimilation experiments on COMS AMVs and CSRs are under way - Impact currently small - work in progress to improve it. • Some data denial results: • A. The “secondary” satellites in an orbital plane have BIG impact – their data are NOT redundant • B. Removing NOAA p.m. orbit gives substantial impact. • C. Removing polar RO has substantial impact (but not as much as B).
Session 1 – summary (2) • Scientific progress on assimilation: • Increasing impact from MW observations affected by cloud and precipitation. Main mechanism is via dynamical adjustment. Makes use of improved RT modelling for cloud. • MWHS-2 FY-3B data used over land and over snow surfaces with some positive impacts. • Positive impact of surface-sensitivity MW channels over land and over sea-ice. Use of retrieved MW emissivity improves results. • Generally good impact for MW and IR radiances using inter-channel correlated observation errors. • Temporally correlated error of GB-GNSS negligible beyond 1.5h • Messages for space agencies: • Scatterometer“virtual constellation” could be improved to give better space/time coverage. • NWP centres rely on high-quality Level-1 data. Efforts still needed to improve quality, including via GSICS. • NWP centres also rely on some high-quality Level-2 processing e.g. AMVs and their coverage and qc information
Session 1 – summary (3) • Radio occultation (GNSS-RO): • Direct impact of GNSS-RO on global NWP skill confirmed. • Indirect impact also confirmed through impact on radiance bias correction. • These data have potential for improving bias correction of radiosondes. • COSMIC-1 system is degrading • RO: FORMOSAT-7/COSMIC-2: A – 6 equatorial, B – 6 polar • “NOAA is fully committed to COSMIC-2” • Importance of extra-tropical RO data confirmed • Expected impact of greatly enhanced future RO system demonstrated, with no saturation at ~100000 profiles per day.
Session 1 – summary (4) • Compared to LEO, a GEO hyperspectral sounder gives higher temporal resolution - OSSE study shows this leads to improved TC track forecasts. • 183 GHz multi-spectral GEO radiometer concept is being studied, focussing on improving the analysis of humidity. Study shows that it is very difficult with this instrument concept to make significant improvements. • Effects of aerosols in NWP: • WGNE case studies – 7(?) institutes participating • Data assimilation – large uncertainties – too few high-quality data sets available • [Wise words from Ralph] • [NWP centres are encouraged to perform impact studies on the effects of varying radiosonde launch times.]
Session 1 – summary (5) • A question: • USA GB-GNSS data are “going commercial” – issues for international dissemination? • Comments to the workshop participants: • Please use standard DA and ensemble DA terminology where possible (add ref.) • ...
