HR: 11:30h
AN: A42A-05    [Abstracts]
TI: The Role of Teleconnections in Rocky Mountain Springtime Warming
AU: * Miller, J A
EM: James.A.Miller@asu.edu
AF: Arizona State University, Department of Geography Box 870104, Tempe, AZ 85287-0104 United States
AB: Using data from 296 stations in Colorado, Montana, New Mexico, and Wyoming, mean spring temperatures for the period 1949-2003 were analyzed to document the spatial and temporal component of temperature trends, identify potential differences in climate change at mountain versus steppe locations, and to assess regional response to atmospheric and oceanic teleconnections. Spring temperature and precipitation in this region are very important for water resources, forest fire conditions, and summer drought severity. Accordingly, many studies have focused on the changing nature of spring climate in the Rocky Mountain States. Of the 296 stations analyzed, 222 demonstrated significant trends in mean spring temperature as indicated by a linear regression analysis using a significance level of 0.10; only two stations demonstrated a statistically significant decrease in temperature over the 55-year period. The region wide warming ranged from 2.06§C in Montana to 1.34§C in New Mexico. The north-south gradient also exists in two other measures of temperature change, the number of stations with significant trends and the number of stations in each state with a warming trend in excess of 2§C. Across the region, there is little indication that sites at higher elevation are warming at a faster rate than lowland stations. In fact, there is evidence that grassland locations in eastern Montana are warming much faster than valley or mountain sites in central or western portions of the state. The warming at stations east of 106øW in Montana is 0.61øC degrees higher than the rest of the state, a statistically significant result. The plains and mountain station difference in warming was not found elsewhere in the research. While the entire region has experienced spring warming over the past 55 years, there are different atmospheric and oceanic teleconnection associated with this phenomenon. The Pacific North American (PNA) teleconnection is important regionally, but the importance of both the Pacific Decadal Oscillation (PDO) and North Pacific (NP) are generally limited to Montana. The El-Nino Southern Oscillation (ENSO) is a primary control on winter and spring climate in Montana, Colorado, and New Mexico, but the direction of the relationship changes from north to south. Zero-lag correlations between the various teleconnections and spring temperatures are usually quite high. However, more important for water resources management and agriculture, the persistence of the teleconnections offers some predictive capability in forecasting spring temperatures from late fall or winter indices. For instance, the correlation between the winter ENSO index and spring temperatures in New Mexico and Colorado is actually stronger than that with no lag. Due to the complex role atmospheric and oceanic teleconnections play in modulating springtime climate in the Rocky Mountains, canonical correlation analysis was performed between the station temperature dataset and sea-surface temperature (SST) and upper-level height fields.
DE: 3399 General or miscellaneous
DE: 4215 Climate and interannual variability (3309)
DE: 3309 Climatology (1620)
DE: 3319 General circulation
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting