Role of resolution in regional climate change projections over China

Abstract

This paper investigates the sensitivity of projected future climate changes over China to the horizontal resolution of a regional climate model RegCM4.4 (RegCM), using RCP8.5 as an example. Model validation shows that RegCM performs better in reproducing the spatial distribution and magnitude of present-day temperature, precipitation and climate extremes than the driving global climate model HadGEM2-ES (HadGEM, at 1.875° × 1.25° degree resolution), but little difference is found between the simulations at 50 and 25 km resolutions. Comparison with observational data at different resolutions confirmed the added value of the RCM and finer model resolutions in better capturing the probability distribution of precipitation. However, HadGEM and RegCM at both resolutions project a similar pattern of significant future warming during both winter and summer, and a similar pattern of winter precipitation changes including dominant increase in most areas of northern China and little change or decrease in the southern part. Projected precipitation changes in summer diverge among the three models, especially over eastern China, with a general increase in HadGEM, little change in RegCM at 50 km, and a mix of increase and decrease in RegCM at 25 km resolution. Changes of temperature-related extremes (annual total number of daily maximum temperature > 25 °C, the maximum value of daily maximum temperature, the minimum value of daily minimum temperature in the three simulations especially in the two RegCM simulations are very similar to each other; so are the precipitation-related extremes (maximum consecutive dry days, maximum consecutive 5-day precipitation and extremely wet days' total amount). Overall, results from this study indicate a very low sensitivity of projected changes in this region to model resolution. While fine resolution is critical for capturing the spatial variability of the control climate, it may not be as important for capturing the climate response to homogeneous forcing (in this case greenhouse gas concentration changes).

Future Climate Projection in Northwest China With RegCM4.6

“…In addition, by the end of the 21st century, the differences among the three scenarios will be increasingly obvious. The pattern of maximum warming in this study is consistent with that of Zhang et al () and Shi et al (). Future precipitation will increase in most parts of Northwest China, reaching its maximum at the end of the 21st century; this result can also be found in other studies (Gao et al, 2012; Gao et al, ; Shi et al, ; Zhang et al, ).…”

“…With the near surface air temperature increase, extreme events related to temperature, such as SU, will be more frequent in Northwest China in the 21st century. This phenomenon can be found throughout China and other parts of the world (Beniston et al, 2007;Saeed et al, 2017;Shi et al, 2017;Xu et al, 2012). In the future, the extreme drought in Northwest China will ease; for example, the extreme index CDD will continue to decrease, and the main reasons for drought mitigation in this region may be as follows: (1) the melting of ice and snow along the Qinghai-Tibet Plateau, Tianshan Mountains, and Kunlun Mountains will increase with the near surface air temperature increase, which will increase the source of water vapor in this region, and (2) the increased temperature will enhance the water cycle in this region, which in turn will affect precipitation-related extreme events.…”

“…Future climate assessments, particularly of precipitation, will have a critical impact on this region. However, the results previously simulated by global climate models have a large bias over this region (Shi et al, ), and the application of regional climate models to Northwest China is more important and more urgently needed than ever.…”

Projected changes in autumn rainfall over West China: Results from an ensemble of dynamical downscaling simulations

“…On the other hand, horizontal resolutions have some influences on the projection for regional or local climate change (Kopparla et al, 2013;Lee and Hong, 2014;Prein et al, 2016;Shi et al, 2017). Due to coarse resolutions, some regional or local phenomena may be precluded in the CMIP5 global climate models (GCMs) (Giorgi et al, 2009).…”

Evaluation of multi‐RCM high‐resolution hindcast over the CORDEX East Asia Phase II region: Mean, annual cycle and interannual variations

“…Using the Regional Integrated Environment Modelling System, version 2.0 (RIEMS2.0), Zhao (2013) tested the ability of RIEMS2.0 to simulate long-term climate and climate changes in East Asia and to provide a basis for further development and applications. The role of horizontal resolution on the projection of future climate over China was investigated using a regional climate model RegCM4 (Shi et al, 2017). Ji and Kang (2015) also simulated the changes of extreme climate events at the end of the 21st century with RegCM4, and found that the model simulated temperature extremes more accurately than precipitation.…”