Akila Sampath

Date of Award

January 2017

Document Type


Degree Name

Master of Science (MS)


Atmospheric Sciences

First Advisor

Dr. Jianglong Zhang


Using ground-based observations, as well as reanalysis and Coupled Model Intercomparison Project Phase 5 (CMIP5) data, the long-term changes in precipitation and surface temperature are studied for the Northern Great Plains (NGP) region for the period of 1965-2005. Significant positive trends of ~1-2 °C/41 years in annual mean temperature are found across North Dakota and Minnesota. This study also suggests that the eastern part of the NGP region is wetter than the western part of the NGP, for the past 41 years. In addition, the spatial-temporal changes of precipitation and temperature of the region, as well as their linkages to Multivariate El-Niño-Southern Oscillation (ENSO) Index (MEI), are investigated through empirical orthogonal function (EOF) analysis using reanalysis and CMIP5 data. The NGP’s temperature field exhibits larger increasing trends in the winter season, while the largest variations in precipitation are found for the summer season. This study further indicates that MEI is positively correlated with winter temperature in North Dakota, and ENSO could also be associated with variations in summer precipitation of the NGP region.