20th Conference on Weather Analysis and Forecasting/16th Conference on Numerical Weather Prediction

P4.16

Diagnosis of winter time cold bias in the ETA and NMM Models

Hui-Ya Chuang, SAIC and NOAA/NWS/NCEP, Camp Springs, MD; and M. Ek, K. Mitchell, V. Wong, and Z. Janjic

Low-level cold biases in both NCEP Meso Eta and Nonhydrostatic Meso Models (e.g., NMM) have been frequently observed at many locations in the past winter. Although these cold biases usually persisted over an extended period of time, the worst cold biases occurred during the night time when atmosphere was relatively stable. While the two models have very similar physics package, the cold biases were more pronounced in the NMM than in the Eta Models.

Tests have begun which will investigate the sources of cold biases in both models. The model-predicted surface energy budget components, i.e. radiation, sensible heat, latent heat, and ground heat fluxes, as well as land surface fields that affect these fluxes are compared against observations at the locations where cold biases existed. In addition, a comparison between the Eta and NMM models is made to investigate why the cold biases are greater in the NMM. The results of these cold bias diagnoses and of the experiments that are carried out to correct the cold biases will be presented.

extended abstract  Extended Abstract (116K)

Poster Session 4, Thursday Posters
Thursday, 15 January 2004, 9:45 AM-11:00 AM, Room 4AB

Previous paper  Next paper

Browse or search entire meeting

AMS Home Page