[email protected] status of pp kenda cosmo general meeting, sibiu, 2 – 5 sept. 2013 1...

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christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst, Offenbach, Germany Contributions / input by: Hendrik Reich, Andreas Rhodin, Annika Schomburg, Ulrich Blahak, Yuefei Zeng, Roland Potthast Yuefei Zeng, Klaus Stephan, Africa Perianez, Michael Bender (DWD) Chiara Marsigli, Tiziana Paccagnella (ARPA-SIM) Lucio Torrisi (CNMCA) Daniel Leuenberger, Luca Weber (MeteoSwiss) Mikhail Tsyrulnikov, Igor Mamay (HMC) Amalia Iriza (NMA) general overview assimilation of SEVIRI-derived cloud top height in LETKF

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Page 1: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1

Status Report PP KENDA

Christoph SchraffDeutscher Wetterdienst, Offenbach, Germany

Contributions / input by:

Hendrik Reich, Andreas Rhodin, Annika Schomburg, Ulrich Blahak, Yuefei Zeng, Roland Potthast

Yuefei Zeng, Klaus Stephan, Africa Perianez, Michael Bender (DWD)

Chiara Marsigli, Tiziana Paccagnella (ARPA-SIM)

Lucio Torrisi (CNMCA)

Daniel Leuenberger, Luca Weber (MeteoSwiss)

Mikhail Tsyrulnikov, Igor Mamay (HMC)

Amalia Iriza (NMA)

• general overview

• assimilation of SEVIRI-derived cloud top height in LETKF

Page 2: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 2

LETKF: implementation

experiment chain in NUMEX set up

• GME LETKF exp. (Nens = 40) June 2011 for lateral BC:

somewhat too little spreadparticularly over Europe,but LBC spread at least aslarge as from COSMO-SREPS

(Nens = 12)

ana. spread

ana. rmse

• for COSMO-LETKF: .

lateral BC by direct interpolationfrom 60 km to 2.8 km(moderate noise at model top & surface, acceptable)

• MCH / ARPA-SIM: resolution gap IFS-EPS(32 km to 2.8 km) tested: ok

Page 3: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 3

LETKF: implementation

experiment chain in NUMEX set up

• lateral BC by direct interpolation from 60 km to 2.8 km

• KENDA:

– 1-hourly cycling, radiosonde, aircraft, wind profiler, synop; 40 ens. members

– assimilation only, optimally takes ~ 1 real day for 1 day of assimilation,but in fact: ~ 1 – 4 real months for 1 week of

assimilation !(without forecasts !!) only 3 experiments so far

• Hendrik: new flexible stand-alone scripts to run LETKF experiments without using NUMEX / archive very limited disk space

1 real day for 1 day of LETKF assimilation

• to do: implement evaluation / verification tools in script suite

• may become very suitable tool for users outside DWD (academia)

• offline adaptive estimation of obs errors in observation space

• multi-step analysis approach (different localization radii for different sets of obs)

Page 4: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 4

LETKF: ensemble forecasts (20 ens. members)

KENDA / COSMO-DE-EPS

max. 10-m wind gusts 2-m temperature precipitation

results of LETKF (without explicit surface / soil perturbations) :

4 – 12 June 2011

larger rmse,initially larger spread

larger rmse,equal spread

larger rmse,larger spread

RMSE

spread

Page 5: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 5

• LETKF technically works

• comparison with surface observations suggest

– generally: LETKF better than NO_OBS, but worse than nudging

– assimilation of surface pressure appears to work particularly well

• LETKF_DET analysis very close to LETKF ensemble mean

• SPPT has only small but positive impact

LETKF at MCH, compare det. LETKF analysis with nudging

• COSMO-2, Nens = 40, LETKF as at DWD

• lateral BC from IFS (det./EPS); soil moisture from COSMO-2

Page 6: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 6

LETKF: implementation of verification

• production of ‘full’ NetCDF feedback files

done: COSMO observation operators (conventional obs) integrated in 3DVAR package

to be done (this autumn !) : extend flow control (read correct Grib files etc.)

• ensemble-related diagnostic + verification tool, using feedback files :(Iriza, NMA)

– ensemble scores implemented, further testing required

Page 7: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 7

accounting for model error

• stochastic perturbation of physics tendencies (SPPT)(Torrisi)

–implemented in (private) V4_26

–tests at CNMCA / MCH / ARPA-SIM (WG7)

• Pattern Generator (for random fields with prescribed correlation scales)(Tsyrulnikov et al.)

–based on a stochastic partial differential equation approach

–basic version developed, being revised to make it efficient

–being embedded in COSMO code

–2-D version planned for next year

Page 8: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 8

high-resolution obs

• radar

–obs operators finished, assimilation works technically

–radial winds vr in LETKF: Yuefei Zeng (DWD, until summer 2014)

need to test thinning / superobbing strategies

3-hour assimilation with 1-hrly cycle done (different localization radii)

–vr + reflectivity Z in LETKF: Theresa Bick (HErZ-I Bonn, until end 2014 at least)

• GPS slant path delay

–obs operator (incl. TL / adjoint) implemented in 3DVar, approximations tested

–implementation in COSMO should start soon

Page 9: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 9

high-resolution obs

• (SEVIRI-based, radiosonde-corrected) cloud top height : see next slides(Schomburg)

• new task: microwave radiometer & Raman lidar T- , q- profiles(Haefele, MCH)

• direct assimilation of SEVIRI radiances (window channels for cloud info)(Perianez)

–technically implemented (obs operator (RTTOV), reading / writing)

–work on monitoring / assimilation start in Nov.

Page 10: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 10

• avoid too strong penalizing of members with high humiditybut no cloud

• avoid strong penalizing of members which are dry at CTHobs but have a cloud or even only high humidity close to CTHobs

search in a vertical range hmax around CTHobs fora ‘best fitting’ model level k, i.e. with minimum ‘distance’ d:

Z [km]

RH [%]

CTHobs

2

max

2 )(1

))()((min obskobskk

CTHhh

RHfRHfd

function of relative humidity

height ofmodel level

k

= 1

• use f (RHobs=1) – f (RHk)

and CTHobs – hk

as 2 separate obs increments in LETKF

if cloud observed with cloud top height CTHobs ,what is the appropriate type of obs increment ?

(if above a layer with cloud fraction > 70 %, then choose top of that layer)

use of (SEVIRI-based) cloud top height (CTH) ‘observations’ in LETKF: method

k1

k2

k3

k4

k5

Cloud top

model profile

Page 11: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 11

3

6

9

Z [km]

„no high cloud“

„no medium cloud“

„no low cloud“

CLC

• assimilate cloud fraction CLCobs = 0

separately

for high, medium, low clouds

• model equivalent:

maximum CLC within vertical range

type of obs increment , if no cloud observed ?

use of (SEVIRI-based) cloud top height (CTH) ‘observations’ in LETKF: method

model profile

Page 12: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 12

relative humiditycloud covercloud water

cloud iceobserved cloud top

3 lines on one colour indicate ensemble mean and mean +/- spread

• 1 analysis step , 17 Nov. 2011, 6 UTC (wintertime low stratus)

vertical profiles

• example: missed cloud event

CTH single-observation experiments

Page 13: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 13

observed cloud top

observation location

• example: missed cloud event

specific water content [g/kg]

relative humidity [%]

cross section of analysis increments for ensemble mean

CTH single-observation experiments

Page 14: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 14

CTH single-observation experiments

temperature profile (mean +/- spread)

• example: missed cloud event

first guess analysis

1000 m

2000 m

3000 m

observed cloud top

LETKF introduces inversion due to RH(CTH) T cross correlations in first guess ensemble perturbations

270 K 280 K 290 K 270 K 280 K 290 K

Page 15: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 15

relative humiditycloud covercloud water

cloud iceobserved cloud top

3 lines on one colour indicate ensemble mean and mean +/- spread

vertical profiles

• example: false alarm cloud assimilated quantity: cloud fraction (= 0)

CTH single-observation experiments

Page 16: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 16

high cloud cover [octas]

FG

ANA

LETKF decreases erroneous cloud cover despitevery non-Gaussian distributions

mid-level cloud cover [octas]

FG

ANA

• example: false alarm cloud assimilated quantity: cloud fraction (= 0)

FG

ANA

low cloud cover [octas]

cover

CTH single-observation experiments

observation increments - histogram over ensemble members

Page 17: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 17

0:00 UTC 6:00 UTC 12:00 UTC 17:00 UTC

cycled assimilation of dense CTH obs

observed cloud top height (CTH)

1-hourly cycle over 21 hours, 13 Nov., 21 UTC – 14 Nov. 2011, 18 UTC(wintertime low stratus)

Page 18: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 18

18

0:00 UTC 6:00 UTC 12:00 UTC 17:00 UTC

cycled assimilation of dense CTH obs :LETKF setup

• thinning: use obs at every 5th grid pt.

• adaptive covariance inflation, adaptive localisation scale ( ~ 35 km)

• Observation error variances : relative humidity = 10 %cloud cover = 3.2 octa

cloud top height [m] :

Page 19: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 19

19

cycled assimilation of dense CTH obs

RMSE

spread

time series of first guess errors of ensemble mean / spread of ensemble

averagedover

cloudy obs

locations

averagedover

cloud-free obs

locations

underdispersive,but no trend for reductionof spread

Page 20: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 20

RMSE

bias

time series of first guess errors of RH at observed CTH (det. run), averaged over cloudy obs locations

cycled assimilation of dense CTH obs

no assimilationwith cloud assimilation

CTH assimilation : reduces RH (1-hour forecast) errors

Page 21: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 21

RMSE

bias

time series of first guess errors of RH at observed CTH (det. run), averaged over cloudy obs locations

cycled assimilation of dense CTH obs

no assimilationwith cloud assimilation

CTH assimilation : reduces RH (1-hour forecast) errors

assimilation of conventional obs only assimilation of conventional + cloud obs

localization scale: adaptive / 20 km

Page 22: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 22

cycled assimilation of dense CTH obs

time series of first guess errors, averaged over cloud-free obs locations(errors are due to false alarm cloud)

mean square error of cloud fraction [octas]

error reduced(almost) everywhere

Page 23: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 23

23

No assim

no assimilation cloud assimilation

conventional only conventional + cloud

total cloud coverof first guessfields after

20 hours of cycling

CTH obs

satellite obs

cycled assimilation of dense CTH obs

Page 24: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 24

Summary

•assimilation of CTH by LETKF reduces errors of first guess (1-h forecast)

tends to introduce humidity / cloud where it should (+ temperature inversion)

tends to reduce ‘false-alarm’ clouds

despite non-Gaussian pdf’s

•no sign of filter collapse (decrease of spread)

•next: evaluate forecast impact

use of (SEVIRI-based) cloud top height (CTH) ‘observations’ in LETKF

Page 25: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 25

Thank you for your attention

Questions ?

Status of PP KENDA

Page 26: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 26

LETKF: implementation

GME COSMO

ensemble members 40 + 1 (3DVar) 40 + 1 (det. Run)

horiz. resolution (ens.) ~ 60 km (ni128) 2.8 km

horiz. resolution (det.) ~ 30 km (ni256) 2.8 km

vertical localis. length scale (ln p) 0.3 (fut.: 0.075 - 0.5) 0.3 ; 0.075 – 0.5

horiz. localisation length scale 300 km 100 km

adaptive horiz. localisation - (not used) used in latest exp.

additive covariance inflation 3DVar - B -

adaptive multiplicative cov. infl. yes yes

conventional obs yes yes

satellite radiances AMSU-A -

GPS-RO new exps -

radar data - passive

update frequency 3 h 1 h ( 30 / 15 min)

Page 27: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 27

LETKF: implementation

• multistep analysis (batch assimilation) implemented motivation:

• local / nonlocal observations (e.g. radiances)

• different observation errors better use different localization scales

• in view of adaptive localization: different obs densities (conventional / radar)

(Perianez et al.: work on paper with theoretical concept + toy model/ idealised experiments)

next step: test with radar / SEVIRI CTH data

• Hendrik: new flexible stand-alone scripts to run LETKF experiments without using NUMEX / archive very limited disk space

1 real day for 1 day of LETKF assimilation

• to do: implement evaluation / verification tools in script suite

• may become very suitable tool for users outside DWD (academia)

Page 28: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 28

low clouds mid-level clouds high clouds

cycled assimilation of dense CTH obs

‘false alarm’ cloud cover

(after 20 hrs cycling)

conventional+ cloud

conventionalobs only

Page 29: Christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst,

[email protected] of PP KENDACOSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 29

Low cloud cover (COSMO)

PBPV – 03/2013

29

17:00 UTCCloud assim

convCloud +conv

No assim