Report from DAOS-WG (Data Assimilation and Observing Systems) Presented by Tom Hamill NOAA Earth System Research Lab Physical Sciences Division (tom.hamill@noaa.gov) Prepared by Tom Hamill and Roger Saunders, with input from WG members

presented at GIFS-TIGGE meeting, Boulder CO, June 2012

Current membership

Ron Gelaro(D),

Co-chair

NASA, USA

Roger Saunders(O),

Co-chair

Met Office, UK

Stefan Klink(O)

DWD, Germany

Carla Cardinali(D)

ECMWF

Chris Velden (O)

Univ Wisconsin -

CIMSS, USA

Tom Hamill(D)

NOAA/ESRL, USA

Tom Keenan (O)

CAWCR, Australia

Rolf Langland (D)

NRL, USA

Bertrand Calpini (O)

MeteoSwiss, Switzerland

Andrew Lorenc (D)

MetOffice, UK

Florence Rabier(D/O)

Météo-France

Prof. Bin Wang(D), Chinese

Academy of Sciences,

China

Michael Tsyrulnikov (D)

HydroMet Centre,

Russia

Mark Buehner (D)

Environment Canada

Sharan Majumdar (D)

RSMAS, University of

Miami, USA

O=Observations D=Data Assimilation

DAOS-WG objectives

Address data assimilation issues, including the

development of improved understanding of the sources of

errors in analyses and forecasts and growth of errors

during data assimilation cycle.

Promote research activities that lead to the better use of

observations for global NWP and an understanding of their

value.

Provide input and guidance for THORPEX regional

campaigns for the deployment of observations to achieve

scientific objectives.

DAOS-4 WG meeting Exeter 27-28 June 2011

• Reviewed targeting paper; updates on THORPEX campaigns; reviewed observing systems; reviewed developments in data assimilation

Observation impact, NRL (US Navy, US NASA, Canadian Met Centre)

In three different NWP systems a quantification of the overall impact of various

observation types using adjoint methods. See Gelaro et al., MWR, Nov 2010.

ECMWF observation impact

Ref: Cardinali, QJRMS 2009, DOI: 10.1002/qj

Similar dominance of AMSU-A. AIRS also big impact (not in Gelaro study)

Sharanya Majumdar,

U. Miami, generated

a report for THORPEX

(and eventual BAMS

article) summarizing

targeted observation

research.

Targeting statement, WMO meeting, Sedona, AZ, USA (May 2012)

• "The THORPEX-DAOS working group recently delivered its

comprehensive report on observation targeting. Its main message is

that there has been a paradigm shift in targeting with respect to 8

year ago; there is now less optimism about targeting having a

breakthrough impact in the extra-tropics. While the scientific

principle of improving forecasts with targeted observations has been

validated, the goal of adding sufficient observations over the entire

target subspace has proven to be logistically difficult to achieve.

Thus, the potential benefits in terms of forecast skill improvements

have not been fully realized. Targeted observation has, however,

been demonstrated to be effective for tropical cyclone forecasting,

through the use of dropsondes and rapid-scan satellite winds. The

targeted use of off-time (06UTC and 18UTC) radiosonde data has

been shown to improved mid-latitude forecasts."

Impact of assimilating dropsondes on typhoon track error during summer T-PARC

Tropical cyclone track forecast errors during the Summer T-PARC period for

four assimilation-forecast systems. The solid (dashed) lines represent

parallel analysis-forecast cycles excluding (including) T-PARC

dropwindsonde data.

Demonstrates generally positive results in assimilation of targeted data for TCs

Impact of targeted observations in mid-latitudes

- Previous studies: targeted obs. in dynamically sensitive

regions (via dropsondes) can improve downstream

forecasts in small target regions.

- Studies are now old, when obs. network was thinner and

data assimilation and forecast models less advanced. What

about with modern systems? Impact over broader areas?

- NOAA THORPEX-funded study: using N. Pac. targeted

dropsondes during 2011 winter, perform parallel

assimilations and 5-day deterministic forecasts with and w/o

additional data, using T511 ECMWF model and their 4D-Var

system.

- Conclusion: no evidence for positive impact on metrics over

broader regions. For limited-area regions, still being

evaluated.

Precipitation Threat Skill Scores over CONUS 12-36 hour Forecast

Entire CONUS Western CONUS

No statistically significant differences

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The Concordiasi Project: additional

observations over Antarctica for NWP

F. Rabier, V. Guidard, S. Noton-Haurot, A. Doerenbecher, D. Puech,

P. Brunel, A. Vincensini, H. Bénichou, Météo-France

Ph Cocquerez, CNES

A. Hertzog, F. Danis, IPSL/LMD

T. Hock, S. Cohn, J. Wang NCAR

C. Sahin, A. Garcia-Mendez, J-N Thépaut ECMWF

A. Cress, U. Pfluger, DWD

R. Langland, NRL

G. Verner, P. Koclas, CMC

R. Gelaro, NASA/GMAO

C. Parrett, R. Saunders Met Office

Y. Sato JMA

for more information, see Jan 2010 BAMS

& tinyurl.com/concordiasi and supplementary slides

13

CONCORDIASI: stratospheric super-pressure balloons flight trajectories Sept 2010-January 2011

19 balloons

launched,

13 w. driftsonde.

Drops ~ coincide

with satellite

overpasses.

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Sea-Ice limit

640 Dropsondes (20100923-20101201)

Participants CMC DWD ECMWF GMAO Météo-France Met Office JMA

Data assimilation monitoring statistics over the Antarctic

RMS(O-F) Obs Count

Radiosonde Background Temperature Departures (O-F)

Courtesy F. Rabier, Météo-France

All models have difficulty predicting lowest-level temperatures

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Concluding remarks on ConcordIASI

Concordiasi provided an unprecedented data coverage of meteorological observations over Antarctica

Both dropsonde and gondola information seem to have a positive impact on forecast performance (preliminary results from NRL, DWD, ECMWF and MF)

Gondola temperature data at 60hPa shows the largest model errors in areas of strong gravity-wave activity

Dropsonde information confirms statistics obtained with radiosondes and provide a more global view

Most models have problems predicting the lowest level temperatures.

Development of advanced data hybrid assimilation systems

Methods of hybridizing 4D-Var with ensemble-based

assimilation techniques a very active area of research and

development at many agencies (e.g., CMC, ECMWF, UK

Met Office, NCEP).

Idea is to leverage advantages of both ensemble-based

and variational systems.

More on this in Weds. talk by Jeff Whitaker, NOAA/ESRL.

Use analyses for verification? Evaluation with TIGGE data.

Also, can we learn something about the sources of errors in

analyses?

Can monitoring of analysis differences help detect problems

at various operational centers?

Full presentation at

http://www.esrl.noaa.gov/psd/people/

tom.hamill/analysis-errors-wgne-hamill.pdf

In following slides, examined statistics from a year’s worth of

00Z analyses from CMC, NCEP, ECMWF, UK Met Office,

CMA.

Analysis spread, 250 hPa u component

What’s going on

in tropical

eastern Pacific

and tropical

western Indian

Oceans?

19

Time series of 250 hPa u-wind, eastern equatorial Pacific

CMC, and to lesser extent NCEP,

have much stronger westerly

winds.

20

Time series of 250 hPa u-wind, eastern equatorial Pacific (smoothed)

21

There are periods of time where

both NCEP and CMC are quite

inconsistent, even in time means,

with other analyses.

Consistency of others does

suggest that perhaps there are

some underlying problems with

these two analyses during

certain periods, and actually

with their removal, there may be

a decent consensus on the

wind analysis.

Challenge of data sharing: precipitable water observations available from E-GVAP

There is actually decent coverage of GPS

total precipitable water information over

US, but the data is not shared and

assimilated for lack of (modest) funds to

convert data to internationally agreed-upon

formats & to develop forward operators.

This highlights a general issue of

challenges of sharing data internationally.

c/o Seth Gutman, NOAA/ESRL

Challenge of data sharing: precipitable water observations available from E-GVAP

NCEP Stage IV obs (mm/day)

CTRL – NCEP Stage IV

NEW – NCEP Stage IV

Impact of NCEP Stage IV assimilation

on +12-h forecasts of precipitation.

Sept-Oct 2009 average

(ECMWF, CY35R2; T511 L91)

ECMWF 2011, Philippe Lopez

Example of benefits of sharing data: ECMWF using US radar-based precipitation estimates

Impact on forecast scores for other parameters (Z, T, wind, RH):

- neutral or slightly positive impact on the global scale.

- some hint of positive impact over Europe (days 4-5) and Asia (days 8-10).

Direct 4D-Var assimilation of NCEP Stage IV rain data in ECMWF

E

CM

WF

20

11

RMSE South. Hemis. 500hPa wind

RMSE NH. 500hPa wind RMSE Europe 500hPa temperature

RMSE Asia 850hPa Temperature

good

1 April – 6 June 2010,

T1279 (~15 km global) L91

Satellite data: data availability, new sensors

Hoping for extended life of polar-orbiting satellites to

minimize gaps until US JPSS operational (next slide).

• Contribution to global observing system by other nations increasing (e.g. FY-3 [China], Oceansat-2 [India]) – help fill gaps?

• Hyperspectral sounder now approved by Europe on MTG (Meteosat 3rd-generation, GEO orbit, ~2017).

• Canada evaluating constellation of highly elliptical orbit satellites, possibly deployed as early as 2018-19

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Satellite data processing issues

• Currently only a fraction of the satellite data available is assimilated, in part due to concerns about correlations of errors degrading assimilations.

• Recent research suggests reduced thinning of AMSU-A may be beneficial (ECMWF, Meteo Fr.).

• Selection of dynamically important regions for assimilating data at higher resolution of interest, radiances or rapid-scan motion vectors.

• Extending the use of satellite data in cloudy regions an area of active research.

• Only one scatterometer now

typically assimilated (ASCAT),

with loss of Quikscat. Narrower

swath width than Quikscat,

though.

• Right: ASCAT winds for Irene

and model background

• Trials and monitoring ongoing

using scatterometer on India’s

Oceansat-2.

• Scatterometer not planned for

US’s JPSS due to budget

constraints.

Importance of scatterometer winds

DAOS-WG directions, issues

• DAOS is leading group for DA in WMO (some in WGNE, too). What is its future in WWRP after THORPEX?

• New co-chair, new members, esp. S. American representative

• Improve WMO connections, especially with:

• ET-EGOS (expert team on evolution of global observing system)

• SPARC (Stratospheric Processes/Climate)

• GLASS (Global Land-Atm. System Studies)

• Next meeting in Madison, WI, USA 19-20 Sep 2012

• Also: upcoming DWD DA symposium, Oct 2012

• Joint meeting with MFWR (mesoscale weather forecasting research) under discussion

• DAOS expects to retain its global focus but link more with mesoscale

• Continue deliberating both on observing systems issues and assimilation techniques.

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DAOS-WG Statement on impact of targeted data

• For mid-latitude systems, the value of targeted data is found to be positive but

small on average. The US Winter Storms Reconnaissance Program has found

that targeting results in some improvement in 2-3 day forecasts over N. America.

• Observations in dynamically sensitive areas have a bigger average impact per

observation than those deployed randomly. The cumulative benefit of a small

number of targeted aircraft observations to forecast accuracy over broad

verification regions is smaller than that of other observing systems that provide

observations with a more complete coverage.

• For forecasts of the track of TCs targeted observations have proven to be

beneficial statistically. A simple sampling strategy of observing uniformly around

the TC has been shown to be effective, with most models exhibiting an

improvement.

• There is a need to assess the impact of targeted observations with more user-

focused measures of the value of forecast improvements to society, while

retaining the ability to get significant results from relatively short experiments.

c/o Fanglin Yang, NCEP/EMC

Anomaly correlation over Pacific – North America region

over too broad a region to see impact?