65 - Historical Reconstruction of Precipitation and Temperature Fields over British Columbia

High-resolution atmospheric data plays a crucial role in conducting impact, adaptation, and vulnerability assessments related to hydro-climatic fields. Most General Circulation Models (GCM) and Global Reanalysis data have limited applicability at local or watershed scales due to their coarse spatial resolution and limited temporal resolutions. Dynamical downscaling of such data enhances resolution significantly but is constrained by its high computation cost. As such, this study aimed to reconstruct hourly historical precipitation and temperature at a 4 km grid resolution, spanning the British Columbia Province (364,800 mi2 area) by dynamically downscaling Reanalysis data from 1934 to 2017, using the Weather Research & Forecasting (WRF) Model. The study found satisfactory agreement between downscaled precipitation and observed precipitation from 1946 to 2017, but relatively lower agreement for 1934 to 1945. This is likely due to improvements in reanalysis data and observation datasets over time. The reconstructed temperature matched significantly well with observations consistently throughout 1934-2017, with summer temperatures having stronger agreement than winter. Furthermore, this study examined three significant historical floods in British Columbia. While the WRF-reconstructed precipitation agreed well with observations in the 1978 flood, there was limited agreement in the 1948 and 2017 floods. Nevertheless, the overall trends in basin average precipitation reconstructed by the WRF model matched the observed trends in those years. The study provides an invaluable climate dataset, unique in its fine resolution and extensive spatial coverage for a long historical period, offering vital insights for informed water resources management in British Columbia.