Abstract
AbstractA Met Office Hadley Centre regional climate model, HadRM3P, is used to dynamically downscale the NOAA Twentieth Century Reanalysis, version 2c (20CRv2c), to generate a fine-resolution reconstruction of China’s climate from 1851 to 2010. The downscaled dataset has a small warm and seasonal wet bias (1.4°C; 0.9 mm day−1) relative to recent observations but otherwise represents spatial and temporal trends realistically. Analysis focused on temperature and precipitation shows that downscaling 20CRv2c is found to improve its representation of China’s climatological annual cycle, particularly over areas with sparse observational coverage such as the Tibetan Plateau. The downscaled dataset better represents the interannual variability and trends in observed temperature since 1901 and suggests that China has experienced a significant and sustained increase in temperature of 0.05°C (10 yr)−1 since the 1850s. Chinese precipitation trends have not changed significantly in the recent past or over the past 160 years. This analysis serves as an initial yet imperative step toward improving in-depth understanding of the characteristics and multidecadal drivers of high-impact events over China such as heat waves, droughts, and extreme precipitation.
Highlights
China’s climate is varied and extreme, with intense monsoons in the east, droughts in the north, and extremes of temperature in the west, all influenced by complex orography
Large-scale drivers: Consistency with lateral boundary conditions. Both 20CR-DS and ERA-Interim dataset (ERAI-DS) assume that the PRECIS regional climate model (RCM) can accurately reproduce the large-scale circulation, driven by boundary conditions from the driving reanalyses
The distance between indices of simulation and observation’’ (DISO) index, accounting for spatial correlation coefficient, compares. This basic assessment suggests that both RCM simulations typically follow the large-scale circulation from the lateral boundary conditions for both reanalyses, with some weakening of the summer monsoon signal expected in the downscaled output within our areas of interest
Summary
China’s climate is varied and extreme, with intense monsoons in the east, droughts in the north, and extremes of temperature in the west, all influenced by complex orography. We present trends in temperature and precipitation anomalies over the past 30–160 years, derived from RCM data that provide a finer resolution and longer time frame than has previously been available This analysis serves as an initial, yet imperative, step toward improving understanding of the characteristics and drivers of high-impact weather events in the region, such as heat waves, droughts, and extreme precipitation. The 20CRv2c provides quasi-observational data of standard atmospheric variables (winds, temperature and humidity) at 6-hourly time steps It has a horizontal spatial resolution of ;200 km [spherical harmonic truncation at wavenumber 62 (T62)] and 28 pressure levels spanning the period from 1850 to 2010. The uncertainty around western China’s historic climate is high Such factors limit the breadth of observation-based validation that can be reasonably conducted on our downscaled simulations, and we include a comparison with multiple global reanalysis datasets to better assess issues of uncertainty.
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