Climate Change and Climate Variability
Using the Community Earth System Model version 1 for Quantifying the Impacts of Internal Climate Variability on Hydrology over the Hanjiang River Watershed
Author: Meijia Zhuan Supervisor: Jie Chen
School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan, Hubei, 430072
Abstract: Evaluating hydrological impacts of climate change has raised widespread concerns recently, in which internal climate variability plays a vital role. It poses limits to climate predictability and reverses the sign and magnitude of anthropogenic response at smaller spatial and shorter time scales. However, it didn’t receive the full credit and is usually ignored in researches. The objectives are to (1) verify the reliability of multi-member ensembles of climate models in terms of simulating the internal climate variability for various climate conditions, (2) propose a research framework to assess the impacts of internal climate variability on hydrology. Specifically, the decadal variability of observed precipitation and temperature were compared to those of multi-member ensembles, as well as the inter-member variability of climate models. The proposed framework consists of a three-stage modeling chain of detrending, bias correction and hydrological modeling. The study was conducted over the Hanjiang River watershed using the 30-member ensemble of the Community Earth System Model (version 1) as an example. The results generally showed that the multi-member ensemble of climate models did a reasonable job at predicting the internal climate variability; the detrending method was able to remove the climate change signal from the climate time series; the remained decadal and inter-member variability can be considered as the internal climate variability; the bias correction method was capable of not only reducing the biases of simulated precipitation and temperature, but also preserving the internal climate variability. Overall, the post-processed climate time series is able to be used with hydrological models for assessing the impacts of internal climate variability on hydrology.
Key words: Internal climate variability; Hydrological impacts; Community Earth System Model (version 1); Hanjiang River watershed
State Key Laboratory of Water Resources & Hydropower Engineering Science, Wuhan University