Estimation of observation impact using the NRL atmospheric variational data assimilation adjoint system

Rolf H. Langland; Nancy L. Baker

doi:10.3402/tellusa.v56i3.14413

Estimation of observation impact using the NRL atmospheric variational data assimilation adjoint system

Tellus

Volume 56 (2004): Issue 3

By: Rolf H. Langland and Nancy L. Baker

Open Access

|Jan 2004

Abstract

An adjoint-based procedure for assessing the impact of observations on the short-range forecast error in numerical weather prediction is described. The method is computationally inexpensive and allows observation impact to be partitioned for any set or subset of observations, by instrument type, observed variable, geographic region, vertical level or other category. The cost function is the difference between measures of 24-h and 30-h global forecast error in the Navy Operational Global Atmospheric Prediction System (NOGAPS) during June and December 2002. Observations are assimilated at 00UTC in the Naval Research Laboratory (NRL) Atmospheric Variational Data Assimilation System (NAVDAS). The largest error reductions in the Northern Hemisphere are produced by rawinsondes, satellite wind data, and aircraft observations. In the Southern Hemisphere, the largest error reductions are produced by Advanced TIROS Operational Vertical Sounder (ATOVS) temperature retrievals, satellite wind data and rawinsondes. Approximately 60% (40%) of global observation impact is attributed to observations below (above) 500 hPa. A significant correlation is found between observation impact and cloud cover at the observation location. Currently, without consideration of moisture observations and moist processes in the forecast model adjoint, the observation impact procedure accounts for about 75% of the actual reduction in 24-h forecast error.

References

Baker , N. L. and Daley , R. 2000 . Observation and background adjoint sensitivity in the adaptive observation targeting problem . Q. J. R. Meteorol. Soc . 126 , 1431 – 1454 .
Search in Google Scholar Back to article
Bouttier , E and Kelly , G . 2001 . Observing system experiments in the ECMWF 4D-Var data assimilation system . Q. J. R. Meteorol. Soc . 127 , 1469 – 1488 .
Search in Google Scholar Back to article
Daley , R. and Barker , E. 2001 . NAVDAS Source Book 2001. NRL/PU/7530-01-441. Available from the Naval Research Laboratory, Monterey, CA, 163 pp.
Search in Google Scholar Back to article
Fourrie , N. , Doerenbecher , A. , Bergot , T. and Joly , A. 2002 . Adjoint sensitivity of the forecast to TOVS observations . Q. J. R. Meteorol. Soc . 128 , 2759 – 2777 .
Search in Google Scholar Back to article
Guymer , L. 1978 . Operational application of satellite imagery to synoptic analysis in the Southern Hemisphere. Technical Report No. 26 , Bureau of Meteorology , Melbourne , Australia .
Search in Google Scholar Back to article
Hogan , T. F. , Rosmond , T. E. and Pauley , R. L. 1999 . The navy operational global atmospheric prediction system: recent changes and testing of gravity wave and cumulus parameterizations. In: Proceedings of the 13th Conference on Numerical Weather Prediction , Denver, CO, Am. Meteorol. Soc. , 60 - 65 .
Search in Google Scholar Back to article
Langland , R. H. , Shapiro , M. A. and Gelaro , R. 2002 . Initial condition sensitivity and error growth in forecasts of the 25 January 2000 East Coast snowstorm. Mon. Wea. Re v . 130 , 957 – 974 .
Search in Google Scholar Back to article
McNally , A. P. 2002 . A note on the occurrence of cloud in meteorologically sensitive areas and the implications for advanced infrared sounders . Q. J. R. Meteorol. Soc . 128 , 2551 – 2556 .
Search in Google Scholar Back to article
Rabier , F. , Klinker , E. , Courtier , P. and Hollingsworth , A. 1996 . Sensitivity of forecast errors to initial conditions . Q. J. R. Meteorol. Soc . 122 , 121 – 150 .
Search in Google Scholar Back to article
Rao , P. A. , Velden , C. S. and Braun , S. A. 2002 . The vertical error characteristics of GOES-derived winds: description and experiments with numerical weather prediction . J. Appl. Meteorol . 41 , 253 – 271 .
Search in Google Scholar Back to article
Reale , A. L. , Chalfant , M. L. , Allegrino , A. S. , Tiley , F. H. , Gerguson , M. P. et al . 2003 . Advanced-TOVS (ATOVS) sounding products from NOAA polar orbiting environmental satellites. In: Proceedings of the 12th Conference on Satellite Meteorology and Oceanography, Long Beach, CA, paper JP1.15.
Search in Google Scholar Back to article
Rosmond , T. E. 1997. A Technical Description of the NRL Adjoint Modeling System. NRL/MR/7532/97/7230. Available from the Naval Research Laboratory, Monterey, CA , 62 pp.
Search in Google Scholar Back to article

Articles in this issue

DOI: https://doi.org/10.3402/tellusa.v56i3.14413 | Journal eISSN: 3035-9554

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Language: English

Page range: 189 - 201

Submitted on: Jul 30, 2003

Accepted on: Nov 26, 2003

Published on: Jan 1, 2004

Published by: Stockholm University Press

In partnership with: Paradigm Publishing Services

© 2004 Rolf H. Langland, Nancy L. Baker, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 56 (2004): Issue 3