martin lange and christoph schraff [email protected] [email protected]
DESCRIPTION
Latest Results on Variational Soil Moisture Initialisation. Martin Lange and Christoph Schraff [email protected] [email protected]. ELDAS experiments for May – December 2000. model setup LM version 3.15 ELDAS configurations, 2-layer soil model - PowerPoint PPT PresentationTRANSCRIPT
05.08.2005 - 1 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
Martin Lange and Christoph [email protected]
Latest Results on Variational Soil Moisture Initialisation
05.08.2005 - 2 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
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 + RH2m observed (‘Rubel’) precipitation
‘no SMA’ - -
ELDAS experiments for May – December 2000
05.08.2005 - 3 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
time series of running monthly mean
model increments
ELDAS domain average of soil moisture increments in bottom layer
SMA increments
evaporation > precipitation in summer SMA increments have more variability
top-layer mean increments are much smaller (not shown)
05.08.2005 - 4 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
time series of running monthly mean
model increments
root mean square over ELDAS domain of bottom-layer soil moisture increments
SMA increments
SMA increments >> model increments,
further increased if RH2m in cost function
05.08.2005 - 5 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
time series of running monthly mean
model increments
root mean square over ELDAS domain of top-layer soil moisture increments
SMA increments
( model increments smaller if
observed precipitation used )
SMA increments < model increments,
yet increased if RH2m in cost function
05.08.2005 - 6 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
time series of running monthly mean
bias
T2m forecasts for 12 and 15 UTC (ELDAS domain and time average for 00-UTC LM runs)
r m s e
SMA reduces bias in warm season SMA reduces rmse by ≥10% in warm season,
use of RH2m slightly beneficialuse of observed precip slightly beneficial
05.08.2005 - 7 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
time series of running monthly mean
bias
RH2m forecasts for 12 and 15 UTC (ELDAS domain and time average for 00-UTC LM runs)
r m s e
use of RH2m reduces bias in May - July SMA reduces rmse by 10 – 30 %,
use of RH2m beneficialuse of observed precip beneficial
05.08.2005 - 8 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
time series of running monthly mean
frequency bias
6- to 30-hour precipitation forecasts (ELDAS domain average for 00-UTC LM runs)
5 mm threshold
SMA strongly reduced bias, increases TSS by about 5 – 10 %
use of RH2m : neutral impactuse of observed precip : beneficial
TSS
05.08.2005 - 9 -
COSMO General MeetingZürich, 20 - 23 Sept 2005 [email protected]
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
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
Note
• the soil moisture initialisation adapted to the multi-layer soil model is running in the pre-operational LME suite