The Influence of Synoptic-Scale Forcing on Soil Moisture Over the Eastern Canadian Prairies

Abstract

The objective of this study was to examine the spatial and temporal patterns of measured autumn soil moisture on the eastern Canadian Prairies, and to relate the patterns to synoptic-scale forcings such as sea surface temperature anomalies. Spatial and temporal patterns of soil moisture were determined using principal component analysis. The dominant pattern of the average soil moisture principal component was found to be one in which the entire region varied coherently, with the greatest amplitudinal change occurring in central Manitoba. The second pattern had the central area out of phase with the southeast and southwest. The third principal component spatial pattern was a dipole with centres over southern Manitoba and northeastern Saskatchewan. Correlations were tested between the temporal principal component patterns and seven potential synoptic-scale forcings. The highest correlation was found with North Pacific sea surface temperature (SST) anomalies: late spring/early summer SST anomalies appear to influence autumn soil moisture the most. The other six synoptic-scale forcings were found to have very weak correlations with the soil moisture patterns. The results of this study may assist in obtaining a better understanding and allow for predictions of the causes of the spatial and temporal soil moisture patterns in the eastern Canadian Prairies.