1 / 9

Martin Lange and Christoph Schraff martin.lange@dwd.de christoph.schraff@dwd.de

Latest Results on Variational Soil Moisture Initialisation. Martin Lange and Christoph Schraff martin.lange@dwd.de christoph.schraff@dwd.de. ELDAS experiments for May – December 2000. model setup LM version 3.15 ELDAS configurations, 2-layer soil model

saeran
Download Presentation

Martin Lange and Christoph Schraff martin.lange@dwd.de christoph.schraff@dwd.de

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Latest Results on Variational Soil Moisture Initialisation Martin Lange and Christoph Schraff martin.lange@dwd.de christoph.schraff@dwd.de 05.08.2005 - 1 -

  2. ELDAS experiments for May – December 2000 • model setup • LM version 3.15 • ELDAS configurations, 2-layer soil model • continuous assimilation cycle, 00-UTC forecasts • parameters setup related to soil moisture initialisation (SMA) for 4 experiments • variables in cost function precipitation fields used to update • (for which prediction should soil moisture from one day to next • be improved by design) (evaporation always from model) • ‘SMA-T2m’ T2m precipitation of model forecast • ‘SMA-T2m+Rh2m’ T2m + RH2m precipitation of model forecast • ‘SMA-T2m+Rubel prec.’ T2m observed (‘Rubel’) precipitation • ‘SMA-T2m+Rh2m+Rubel’ T2m + RH2mobserved (‘Rubel’) precipitation • ‘no SMA’ - - 05.08.2005 - 2 -

  3. ELDAS domain average of soil moisture increments in bottom layer time series of running monthly mean model increments SMA increments evaporation > precipitation in summer SMA increments have more variability top-layer mean increments are much smaller (not shown) 05.08.2005 - 3 -

  4. root mean square over ELDAS domain of bottom-layer soil moisture increments time series of running monthly mean model increments SMA increments SMA increments >> model increments, further increased if RH2m in cost function 05.08.2005 - 4 -

  5. root mean square over ELDAS domain of top-layer soil moisture increments time series of running monthly mean model increments SMA increments ( model increments smaller if observed precipitation used ) SMA increments < model increments, yet increased if RH2m in cost function 05.08.2005 - 5 -

  6. T2m forecasts for 12 and 15 UTC (ELDAS domain and time average for 00-UTC LM runs) time series of running monthly mean bias r m s e SMA reduces bias in warm season SMA reduces rmse by ≥10% in warm season, use of RH2m slightly beneficial use of observed precip slightly beneficial 05.08.2005 - 6 -

  7. RH2m forecasts for 12 and 15 UTC (ELDAS domain and time average for 00-UTC LM runs) time series of running monthly mean bias r m s e use of RH2m reduces bias in May - July SMA reduces rmse by 10 – 30 %, use of RH2m beneficial use of observed precip beneficial 05.08.2005 - 7 -

  8. 6- to 30-hour precipitation forecasts(ELDAS domain average for 00-UTC LM runs) time series of running monthly mean frequency bias 5 mm threshold TSS SMA strongly reduced bias, increases TSS by about 5 – 10 % use of RH2m : neutral impact use of observed precip : beneficial 05.08.2005 - 8 -

  9. Conclusions • current implementation of soil moisture initialisation is strongly beneficial for prediction of daytime T2m and RH2m, and also beneficial for precipitation forecasts • inclusion of RH2m in addition to T2m in cost function further improves predicted RH2m • use of observed precipitation to update soil moisture in time further improved prediction of daytime RH2m and of precipitation • best results with both modifications Note • the soil moisture initialisation adapted to the multi-layer soil model is running in the pre-operational LME suite Further Plan • investigation to replace the variationally derived relationship between 2-m temperature (+ 2-m humidity) and soil moisture by a parameterized regression. • this would render obsolete the extra model forecast integrations required in the current SMI implementation 05.08.2005 - 9 -

More Related