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High-resolution Regional Reanalysis for the European CORDEX Domain Christian Ohlwein1,2, Jan Keller1,4, Petra Friederichs2, Andreas Hense2, Susanne Crewell3, Sabrina Bentzien1,2, Christoph Bollmeyer1,2, Jessica Keune1,2, Ieda Pscheidt1,2, Stephanie Redl1,3, Sandra Steinke1,3, David Willms1,2 1 Hans-Ertel-Centre for Weather Research – Climate Monitoring Branch 2 Meteorological Institute, University of Bonn 3 Institute for Geophysics and Meteorology, University Cologne 4 Deutscher Wetterdienst DWD http://www.herz-tb4.uni-bonn.de

WCRP CORDEX Conference, Brussels, 4-‐7 November 2013

Outline è Development of a regional reanalysis system

§ Set-up and characteristics § Evaluation with independent observation networks

è Perspectives

Christian Ohlwein ■ Hans-Ertel-Centre for Weather Research ■ Climate Monitoring Branch

Objective è Develop methods for monitoring regional climate for

operational use at the German Meteorological Service (DWD)

Atmospheric Reanalyses

è Concept § Assimilation of past observation into a physical model

§ Synthesize heterogeneous monitoring networks

§ Provide (physically consistent) four-dimensional fields

è State-of-the-art § Essential tool for climate monitoring

§ Current reanalyses mainly on the global scale


Observations Data Assimilation Physical Model

Regional Reanalyses


COSMO-REA2 COSMO-DE (2 km)

Regional Reanalysis System


Data Assimilation §  Continuous nudging

SYNOP, SHIP, PILOT, TEMP, AIREP, AMDAR, ACARS,…

§  SST analysis (daily) §  Snow analysis (6-hourly) §  Soil moisture analysis (REA6) §  Latent heat nudging (REA2)

COSMO-REA6 (6.2 km)

§  Limited area model COSMO §  Data assimilation …

ERA-Interim Reanalysis (T255)

COSMO-REA2 (2.0 km)

§  Limited area model COSMO §  Data assimilation …

Regional Reanalysis System


Data Assimilation §  Continuous nudging

SYNOP, SHIP, PILOT, TEMP, AIREP, AMDAR, ACARS,…

§  SST analysis (daily) §  Snow analysis (6-hourly) §  Soil moisture analysis (REA6) §  Latent heat nudging (REA2)

COSMO-DS6 (6.2 km)

§  Limited area model COSMO §  Downscaling (for reference only)

ERA-Interim Reanalysis (T255)

Model Output è Domain (REA6)

§ Setup B (equal volumes) § 848 × 824 grid points

è Variables § ≈ 150 fields (2D/3D) § Output interval

§ 60 min (3D) § 15 min (2D)


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i=1 i=2 i=3 i=4

i=1

i=2

i=3

i=4

i=1 i=2 i=3 i=4 i=5 i=6 i=7 i=8

j=1

j=2

j=3

j=4

j=5

j=6

j=7

j=8

Setup B (equal volumes)

CO

SM

O-R

EA

6

CO

RD

EX

EU

R-1

1

Model Output (REA6/DS6)




è Perspectives


IQ D

ISTA

NCE

[mm

/3h]

DJF

0.00

0.04

0.08

JJA

03 06 09 12 15 18 21 00UTC

0.00

0.04

0.08

0.12

0.16

ERA-INTERIMCOSMO-DSCOSMO-REA6

Precipitation – Distribution


*) cf. Thorarinsdottir et al. (2013): Using proper divergence functions to evaluate climate models

Integrated Quadratic Distance* (IQD) COSMO-CORDEX / German SYNOP stations (2011)

Precipitation – Extremes

<0.1 0.1−1.0 1.0−5.0 5.0−10.0 >10.00.0

0.5

1.0

1.5

2.0

2.5

Precipitation [mm/3h]

Occ

uren

ces

[x10

6 ]

SYNOPCOSMO−REACOSMO−DSERA−INTERIM

20−30 30−40 40−50 50−60 >600.0

0.2

0.4

0.6

0.8

1.0

Precipitation [mm/3h]

Occ

uren

ces

[x10

3 ]

SYNOPCOSMO−REACOSMO−DSERA−INTERIM


Histogram of 3-hourly precipitation events at German SYNOP stations (COSMO-REA6/DS6 simulations, 2011)

*) note the change of support

* *

Precipitation – Log-Odds Ratio


Log-odds ratio for 3-hourly precipitation events compared to German SYNOP stations (COSMO-REA6 simulations, 2011)

Further Evaluation* è Standard evaluation

§ Analysis increments § …

è Remote sensing data

§ AMSU-B Microwave Humidity Sensor § MSG brightness temperature § IWV from GNSS measurements § Ceilometer measurements § …


*) cf. Bollmeyer et al.: Towards a high-resolution regional reanalysis for the European CORDEX domain



è Perspectives


Perspectives è Status

§ COSMO-REA6: 5 years (2007-2011) by end of 2013 § Planned to become operational in mid/end 2014

è Next steps § UERRA: Uncertainties in Ensembles of Regional Re-Analysis (FP7-SPACE)

§ Multi-model ensembles § Ensemble data assimilation

§ Long-term evaluation (!) § Enhanced representation of the coupled soil-vegetation-atmosphere system § …


Hybrid LETKF/ensemble nudging (HErZ)



è Perspectives


Summary è Development

§ Regional reanalysis system CORDEX EUR-11 domain (6.2 km)

§ Continuous data assimilation (nudging) vs. downscaling only

è Evaluation

§ Representation of spatio-temporal variability § Coherence between model and independent observations

è Perspectives

§ Five years (2007–2011) by end of 2013

§ …


Core idea of a “reanalysis”

High-resolution Regional Reanalysis for the European CORDEX Domain Christian Ohlwein1,2, Jan Keller1,4, Petra Friederichs2, Andreas Hense2, Susanne Crewell3, Sabrina Bentzien1,2, Christoph Bollmeyer1,2, Jessica Keune1,2, Ieda Pscheidt1,2, Stephanie Redl1,3, Sandra Steinke1,3, David Willms1,2 1 Hans-Ertel-Centre for Weather Research – Climate Monitoring Branch 2 Meteorological Institute, University of Bonn 3 Institute for Geophysics and Meteorology, University Cologne 4 Deutscher Wetterdienst DWD http://www.herz-tb4.uni-bonn.de

WCRP CORDEX Conference, Brussels, 4-‐7 November 2013

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