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Interpretation of the new high-resolution model LMK Heike Hoffmann heike.hoffmann@dwd.de Volker Renner volker.renner@dwd.de. Aims . - high-resolution numerical weather forecasts include stochastic elements even in the short range
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Interpretation of the new high-resolution model LMK Heike Hoffmann heike.hoffmann@dwd.de Volker Renner volker.renner@dwd.de Interpretation of the new high resolution model LMK
Aims - high-resolution numerical weather forecasts include stochastic elements even in the short range - direct model output should therefore be transformed for point forecasts - probability information of the exceedance for given thresholds and/or warning events should be derived by statistical means Interpretation of the new high resolution model LMK
Method We plan a two step approach 1. Using information of a single model forecast by applying the Neighbourhood Method (NM) 2. Using information resulting from LMK-forecasts that are started every 3 h (LAF-Ensemble) Interpretation of the new high resolution model LMK
Products • Probabilistic information for hazardous weather warnings • - exceedance probabilities for certain threshold values and • warning events for different parameters, (e.g. strong gales, heavy • rain; long list with warning criteria from our forecast department) • „Statistically smoothed” fields for point forecasts • - Expectation Values from spatiotemporal neighbourhood • -simple averaging over quadratic grid boxes Interpretation of the new high resolution model LMK
LMK Total Precipitation [mm/h] 04/01/13, 00 UTC, vv=17-18 Interpretation of the new high resolution model LMK
Exceedance Probability of 1 mm/h, 04/01/13, 17-18 UTC [%] calculated with the NM with 10 grid increments, 3 time levels (t-1, t, t+1) Interpretation of the new high resolution model LMK
Verification results deterministic verification probabilistic verification Interpretation of the new high resolution model LMK
Verification Data LMK forecasts; 2004, Jan 3-17; July 13-27, 1 h values, 00 UTC and 12 UTC starting time; 7-18 h forecast time all SYNOPs available from German stations comparison with nearest land grid point Neighbourhood-Method-Parameters temporal: 3 time levels (3 h); spatial: radius: 10s ( 28 km) Simple Averaging square areas of different size (3*3, 5*5, 7*7, 9*9, 11*11, 15*15, 25*25) temperatures adjusted with -0.65 K/(100 m) Interpretation of the new high resolution model LMK
LMK and LM, Jan 3-17, vv = 7-18, 00 UTC, ETS LMK DMO LMK expectation value LMK median LM DMO LM expectation value LM median threshold [mm/h] Interpretation of the new high resolution model LMK
LMK, Jan 3-17, vv = 7-18, 00 UTC, FBI Interpretation of the new high resolution model LMK
LMK, Jan 3-17, vv = 7-18, 00 UTC, ETS Interpretation of the new high resolution model LMK
LMK, July 13-27, vv = 7-18, 00 UTC, ETS Interpretation of the new high resolution model LMK
Reliability diagram precipitation Jan 2004 Frequency ofobservation Frequency of forecast Interpretation of the new high resolution model LMK
LMK, Jan 3-17, July 13-27 vv = 7-18, 00 UTC, BSS Interpretation of the new high resolution model LMK
Summary • NM seems to work similarly for the LMK fields like for the LM • results for original and postprocessed LMK-fields are slightly better than for LM fields • 00 UTC runs show slightly better scores than 12 UTC runs • scores in winter are much better than in summer, in summer there is more effect in postprocessing • expectation values do not integrate into simple averaging, show advantages especially for intermediate thresholds • BSS vs. climate also show better quality in winter, BSS vs. LMK indicate stronger influence of postprocessing in summer Interpretation of the new high resolution model LMK
Outlook - further work on the NM - investigations on the influence of neighbourhood size and shape - investigations on spatiotemporal autocorrelations of the forecast fields - conceptual and technical optimization of the NM - work on Probabilistic Products for different parameters - development of a new weather-interpretation for the LMK ------------------------------------------------------------------------------- - development of products from the LMK-LAF-Ensemble Interpretation of the new high resolution model LMK
Acknowledgements Many thanks to ... - Andreas Hense and Susanne Theis for the idea and the imple-mentation of the NM for the LM - Ulrich Damrath for his help with the verification - Elke Wolff for introducing me into the NM program package - the DWD for enabling the “Aktionsprogramm 2003” and providing a great working environment - you for your attention and your contribution to the discussion Interpretation of the new high resolution model LMK