HR: 0800h
AN: GC21A-0150    [Abstracts]
TI: Observed and Modeled Temperature Inversions for Fairbanks Alaska
AU: * Bourne, S M
EM: bournesm@gi.alaska.edu
AF: University of Alaska Fairbanks, College of Natural Science, Geophysical Institute, 903 Koyukuk Dr, Atmospheric Science Program PO Box 757320, Fairbanks, AK 99775, United States
AU: Bhatt, U S
EM: bhatt@gi.alaska.edu
AF: University of Alaska Fairbanks, College of Natural Science, Geophysical Institute, 903 Koyukuk Dr, Atmospheric Science Program PO Box 757320, Fairbanks, AK 99775, United States
AU: Zhang, J
EM: ffjz@uaf.edu
AF: Geophysical Institute, 903 Koyukuk Drive PO Box 757320, Fairbanks, AK 99775, United States
AU: Thoman, R
EM: richard.thoman@noaa.gov
AF: National Weather Service -Fairbanks Office, UAF-IARC PO Box 757345, Fairbanks, AK 99775, United States
AB: Human populations in the Arctic are concentrated in complex orographic locations that are inadequately resolved by global climate models. Therefore, it is difficult to construct climate projections useful for humans based on GCM results only. A dynamical downscaling model approach is used over Alaska to provide high-resolution climate information, which aims to capture important local climate phenomena such as surface-based temperature inversions. The focus of this presentation is to analyze inversion characteristics using observed radiosonde data in Alaska and to evaluate how well GCM and downscaled simulations capture key characteristics of inversions. The model component of this project incorporates a multi-scale approach, using the National Center for Atmospheric Research (NCAR) Community Climate System Model Version 3 (CCSM3) and NCEP/NCAR Re- analysis for the large scale climate and the Arctic MM5, for high-resolution simulations. Downscaled Re-analysis results for the period 1994-2004 are compared to observed radiosonde data for the last half-century. These results are compared to downscaled CCSM climate. The first step in this work develops a comprehensive climatology of observed local conditions. Wintertime (October-March) surface-based inversions in Fairbanks are analyzed from 1957-2005 using radiosonde soundings in order to determine characteristics and possible connections to the large-scale climate. Additionally, inversion characteristics were analyzed to determine any trends and variability over time. During the winter months in Fairbanks, there is a high correlation between inversion depth and inversion temperature difference. When the inversion is deep the temperature difference across the inversion is large. Subsequently, surface temperature is negatively correlated to both depth and temperature difference. When surface temperatures are warm, the inversion is shallow with a small temperature difference. Concurrently, when the surface is cool, the inversion is deep and the temperature gradient is large. Additional observed characteristics of inversions such as strength and frequency will be presented and then compared to inversion characteristics from the downscaled simulations.
DE: 0798 Modeling
DE: 1626 Global climate models (3337, 4928)
DE: 1630 Impacts of global change (1225)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting