Assessment of Change in Precipitation Frequency under Future Climate Change Conditions

Abstract

In this study the extreme precipitation under different CCSM3 GCM GHG emissions scenarios is investigated between historical period (wy1901 – wy1999) and projection period (wy2001 – wy2099) for the watersheds in Northern California. For this, a regional climate model (MM5) was set up over the Northern California and then the precipitation was dynamically downscaled from CCSM3 GCM GHG emissions scenario outputs to a regional scale (9-km grid resolution) with 1-hour time increment for both historical period (1900 – 2000) and projection period (2000 – 2100). From this study, it is found that the projected annual 72-hour maximum precipitation values based on CCSM3 A1B, A2, B1 and A1FI have the heavy tails than the historical annual 72-hour maximum precipitation values. Furthermore, CCSM3 A1FI scenario-based annual 72-hour maximum precipitation values are also higher than the historical annual 72-hour maximum precipitation values. In other words, A1FI scenario is one of the worst GHG emissions scenarios, but this scenario is also very important for the future climate change assessment.