Global Monsoon Rainfall - What the future holds?
Abstract
We provide a latest view of global as well as regional monsoonal rainfall and their changes in the twenty-first century as projected by state-of-the-art climate models participated in the Coupled Model Intercomparison Project phase 5 (CMIP5). The global monsoon area (GMA) defined based on the annual range in precipitation will expand mainly over the central to eastern tropical Pacific, the southern Indian Ocean, and eastern Asia. The global monsoon intensity (GMI) and the global monsoon total precipitation (GMP) are likely to increase, implying that monsoon-related precipitation will remarkably increase in a warmer climate. Heavy precipitation indices are projected to increase much more than the mean precipitation, and their percentage changes depend more on the emission scenario compared to those for mean precipitation. Over the Asian monsoon domain, median increase rate for precipitation is larger than that over other monsoon domains, indicating that the sensitivity of Asian monsoon to global warming is stronger than that of other monsoons. For seasonal progress of monsoon rainfall, CMIP5 models project that the monsoon retreat dates will delay, while the onset dates will either advance or show no change, resulting in lengthening of the monsoon season. It is found that the increase of the global monsoon precipitation can be attributed to the increases of moisture convergence due to increased water vapor in the air column and surface evaporation, offset to a certain extent by the weakening of the monsoon circulation (Figure 1).Figure 1: Time series of anomalies during summer season (%; 20 years running mean) relative to the base period average (1986-2005) over the land global monsoon domain for (a) precipitation (mm day-1), (b) evaporation (mm day-1), (c) water vapor flux convergence in the lower (below 500hPa) troposphere (mm day-1), and (d) wind convergence in the lower troposphere (10-3 kg m-2 s-1), based on 23 CMIP5 model monthly outputs. Historical (grey), RCP4.5 (blue), and RCP8.5 (red) simulations are shown in the 10th and 90th percentile (shading), and in all model averages (thick lines). The monsoon domains defined using the criterion by Wang et al. (2011, Clim.Dyn.) for the base period are fixed for the whole period.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMGC33G..03E
- Keywords:
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- 1626 GLOBAL CHANGE / Global climate models;
- 1854 HYDROLOGY / Precipitation