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UBC Theses and Dissertations

Predicting daily stream temperature in British Columbia, Canada, using reanalysis air temperature in statistical models and the hybrid air2stream model Callahan, Lilianne


As air temperature and precipitation patterns change globally, so too will stream thermal regimes which affect water quality and habitat suitability for aquatic life. Models are used to understand past and future stream temperatures and the primary processes that control them. Since water temperature is highly correlated with air temperature, this research investigates the use of reanalysis air temperature data from ECMWF Reanalysis v5 (ERA5) and North American Regional Reanalysis (NARR) as input in three different types of statistical models of stream temperature. ERA5 overall had the best performance, so it was then used as input in the hybrid air2stream model to test how well the model simulates stream temperatures for 23 streams in British Columbia, Canada, during the extreme conditions of a heat wave and a drought. The air2stream model had an average RMSE of 0.96 °C during the calibration period and 1.06 °C during the validation period. During the heat wave from June 25 to July 2, 2021, the average RMSE was 1.39 °C, and during the autumn drought from September 1 to October 31, 2022, the average RMSE was 1.08 °C. The model results indicate general accuracy with higher errors during anomalous conditions.

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