HR: 15:45h
AN: A33B-08    [Abstracts]
TI: Spatiotemporal Variability and Covariability of Temperature, Precipitation, Soil Moisture, and Vegetation in North America for Regional Climate Model Applications
AU: * Castro, C L
EM: castro@atmo.arizona.edu
AF: University of Arizona Department of Atmospheric Sciences, Physics and Atmospheric Sciences Bldg., Rm. 520 1118 East Fourth Street, Tucson, AZ 85721, United States
AU: Beltran-Przekurat, A B
EM: adriana@cires.colorado.edu
AF: CIRES University of Colorado at Boulder, Stadium 255-16, Boulder, CO 80309, United States
AU: Pielke, R A
EM: pielkesr@cires.colorado.edu
AF: CIRES University of Colorado at Boulder, Stadium 255-16, Boulder, CO 80309, United States
AB: Previous work has established that the dominant modes of Pacific SSTs influence the summer climate of North America through large-scale forcing, and this effect is most pronounced during the early part of the season. It is hypothesized, then, that land surface influences become more dominant in the latter part of the season as remote teleconnection influences diminish. As a first step toward investigation of this hypothesis in a regional climate model (RCM) framework, the statistically signficant spatiotemporal patterns of variability and covariability in North American precipitation (specified by the standardized precipitation index, or SPI), soil moisture, and vegetation are determined for timescales from a month to six months. To specify these respective data we use: CPC gauge- derived precipitation (1950-2000), Variable Infiltration Capacity (VIC) Model and NOAH Model NLDAS soil moisture and temperature, and the Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index (GIMMS-NDVI). The principal statistical tool used is multiple taper frequency singular value decomposition (MTM-SVD), and this is supplemented by wavelet analysis for specific areas of interest. The significant interannual variability in all of these data occur at a timescale of about 7 to 9 years and appears to be the integrated effect of remote SST forcing from the Pacific. Considering the entire year, the spatial pattern for precipitation resembles the typical ENSO winter signature. If the summer season is considered seperately, the out of phase relationship between precipitation anomalies in the central U.S. and core monsoon region is apparent. The largest soil moisture anomalies occur in the central U.S., since precipitation in this region has a consistent relationship to Pacific SSTs for the entire year. This helps to explain the approximately 20 year periodicity in drought conditions there. Unlike soil moisture, the largest anomalies in vegetation occur in the southeast U.S. and appear more related to temperature variability. In the core monsoon region, interannual variation in vegetation growth is governed by monsoon precipitation. Future RCM work will use these patterns of long-term variability of soil moisture and vegetation in sensistivity experiments investigating land-surface interactions in the warm season.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1620 Climate dynamics (0429, 3309)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1632 Land cover change
DE: 1637 Regional climate change
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly