Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation
The Community Atmosphere Model version 3 (CAM3) temperature simulation bias is examined in this paper. We compare CAM3 output with European Centre for Medium-Range Weather Forecasts (ECMWF) 40 year reanalysis (ERA-40) data. We formulate a time mean temperature bias equation then evaluate each term i...
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ftcdlib:qt3r74g4fs 2023-05-15T15:15:41+02:00 Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation Pan, Lin-Lin Grotjahn, Richard Tribbia, Joe pp 1411-1427 2010-12-01 application/pdf http://www.escholarship.org/uc/item/3r74g4fs english eng eScholarship, University of California http://www.escholarship.org/uc/item/3r74g4fs qt3r74g4fs public Pan, Lin-Lin; Grotjahn, Richard; & Tribbia, Joe. (2010). Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation. Climate Dynamics: Observational, Theoretical and Computational Research on the Climate System, 35(7), pp 1411-1427. doi:10.1007/s00382-009-0608-6. Retrieved from: http://www.escholarship.org/uc/item/3r74g4fs Earth Sciences Oceanography Meteorology/Climatology Geophysics/Geodesy CAM3 Temperature bias Diabatic heating Northern hemisphere storm tracks Arctic article 2010 ftcdlib https://doi.org/10.1007/s00382-009-0608-6 2016-04-02T18:51:53Z The Community Atmosphere Model version 3 (CAM3) temperature simulation bias is examined in this paper. We compare CAM3 output with European Centre for Medium-Range Weather Forecasts (ECMWF) 40 year reanalysis (ERA-40) data. We formulate a time mean temperature bias equation then evaluate each term in the equation. Our focus is on the Northern Hemisphere winter time. We group the temperature equation terms into these categories: linear advection terms, nonlinear advection terms, transient eddy terms and diabatic heating, and find that linear advection and diabatic bias are the largest. The nonlinear terms (velocity bias advection of temperature bias) are much smaller than each of the other groups of terms at all levels except near the surface. Linear advection terms have dipolar pattern in the Atlantic (negative NW of positive) which reflects the shift of the CAM3 model North Atlantic storm track (NAST) into Europe, especially in the upper troposphere; opposite sign dipolar structure occurs over Alaska (positive) and the north Pacific storm track (negative). The transient advection terms in middle latitudes are larger in the upper troposphere and generally positive along the Atlantic storm track. Along the north Pacific storm track (NPST), the transient terms are negative in the mid and lower troposphere over much of the NPST (positive in upper troposphere). The diabatic heating bias has large values in the tropics along the Intertropical Convergence Zone (ICZ) and along the midlatitude storm tracks. During this time of year the ICZ is mainly in the Southern Hemisphere, but CAM3 emphasizes an ICZ-like heating in the northern hemisphere of the Atlantic and Pacific Oceans. CAM3 tends to have a weaker ICZ, especially in the Atlantic. In midlatitudes, we find large bias in heating by precipitation and vertically averaged net radiation over the NAST, Europe, and the Middle East. Article in Journal/Newspaper Arctic North Atlantic Alaska University of California: eScholarship Arctic Pacific Climate Dynamics 35 7-8 1411 1427 |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Earth Sciences Oceanography Meteorology/Climatology Geophysics/Geodesy CAM3 Temperature bias Diabatic heating Northern hemisphere storm tracks Arctic |
spellingShingle |
Earth Sciences Oceanography Meteorology/Climatology Geophysics/Geodesy CAM3 Temperature bias Diabatic heating Northern hemisphere storm tracks Arctic Pan, Lin-Lin Grotjahn, Richard Tribbia, Joe Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation |
topic_facet |
Earth Sciences Oceanography Meteorology/Climatology Geophysics/Geodesy CAM3 Temperature bias Diabatic heating Northern hemisphere storm tracks Arctic |
description |
The Community Atmosphere Model version 3 (CAM3) temperature simulation bias is examined in this paper. We compare CAM3 output with European Centre for Medium-Range Weather Forecasts (ECMWF) 40 year reanalysis (ERA-40) data. We formulate a time mean temperature bias equation then evaluate each term in the equation. Our focus is on the Northern Hemisphere winter time. We group the temperature equation terms into these categories: linear advection terms, nonlinear advection terms, transient eddy terms and diabatic heating, and find that linear advection and diabatic bias are the largest. The nonlinear terms (velocity bias advection of temperature bias) are much smaller than each of the other groups of terms at all levels except near the surface. Linear advection terms have dipolar pattern in the Atlantic (negative NW of positive) which reflects the shift of the CAM3 model North Atlantic storm track (NAST) into Europe, especially in the upper troposphere; opposite sign dipolar structure occurs over Alaska (positive) and the north Pacific storm track (negative). The transient advection terms in middle latitudes are larger in the upper troposphere and generally positive along the Atlantic storm track. Along the north Pacific storm track (NPST), the transient terms are negative in the mid and lower troposphere over much of the NPST (positive in upper troposphere). The diabatic heating bias has large values in the tropics along the Intertropical Convergence Zone (ICZ) and along the midlatitude storm tracks. During this time of year the ICZ is mainly in the Southern Hemisphere, but CAM3 emphasizes an ICZ-like heating in the northern hemisphere of the Atlantic and Pacific Oceans. CAM3 tends to have a weaker ICZ, especially in the Atlantic. In midlatitudes, we find large bias in heating by precipitation and vertically averaged net radiation over the NAST, Europe, and the Middle East. |
format |
Article in Journal/Newspaper |
author |
Pan, Lin-Lin Grotjahn, Richard Tribbia, Joe |
author_facet |
Pan, Lin-Lin Grotjahn, Richard Tribbia, Joe |
author_sort |
Pan, Lin-Lin |
title |
Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation |
title_short |
Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation |
title_full |
Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation |
title_fullStr |
Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation |
title_full_unstemmed |
Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation |
title_sort |
sources of cam3 temperature bias during northern winter from diagnostic study of the temperature bias equation |
publisher |
eScholarship, University of California |
publishDate |
2010 |
url |
http://www.escholarship.org/uc/item/3r74g4fs |
op_coverage |
pp 1411-1427 |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Arctic North Atlantic Alaska |
genre_facet |
Arctic North Atlantic Alaska |
op_source |
Pan, Lin-Lin; Grotjahn, Richard; & Tribbia, Joe. (2010). Sources of CAM3 temperature bias during northern winter from diagnostic study of the temperature bias equation. Climate Dynamics: Observational, Theoretical and Computational Research on the Climate System, 35(7), pp 1411-1427. doi:10.1007/s00382-009-0608-6. Retrieved from: http://www.escholarship.org/uc/item/3r74g4fs |
op_relation |
http://www.escholarship.org/uc/item/3r74g4fs qt3r74g4fs |
op_rights |
public |
op_doi |
https://doi.org/10.1007/s00382-009-0608-6 |
container_title |
Climate Dynamics |
container_volume |
35 |
container_issue |
7-8 |
container_start_page |
1411 |
op_container_end_page |
1427 |
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