Tropical Pacific trends explain the discrepancy between observed and modelled rainfall change over the Americas

IF 8.5 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES npj Climate and Atmospheric Science Pub Date : 2024-08-29 DOI:10.1038/s41612-024-00750-x

Weiteng Qiu, Matthew Collins, Adam A. Scaife, Agus Santoso

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Abstract

Understanding the causes for discrepancies between modelled and observed regional climate trends is important for improving present-day climate simulation and reducing uncertainties in future climate projections. Here, we analyse the performance of coupled climate models in reproducing regional precipitation trends during the satellite era. We find statistically significant observed drying in southwestern North America and wetting in the Amazon during the period 1979–2014. Historical climate model simulations do not capture these observed precipitation trends. We trace this discrepancy to the inability of coupled simulations to capture the observed Pacific trade wind intensification over this period. A linear adjustment of free running historical simulations, based on the observed strengthening of the Pacific trade winds and modeled ENSO teleconnections, explains the discrepancy in precipitation trends. Furthermore, both the Pacific trade wind trends and regional precipitation trends are reproduced in climate simulations with prescribed observed sea surface temperatures (SST), underscoring the role of the tropical Pacific SST patterns.

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热带太平洋趋势解释了美洲降雨量观测变化与模拟变化之间的差异

了解模型与观测到的区域气候趋势之间存在差异的原因，对于改进当今的气候模拟和减少未来气候预测的不确定性非常重要。在此，我们分析了卫星时代耦合气候模式在再现区域降水趋势方面的表现。我们发现，在 1979-2014 年期间，从统计学角度观测到北美西南部的干燥和亚马逊地区的湿润。历史气候模式模拟无法捕捉到这些观测到的降水趋势。我们将这一差异归因于耦合模拟无法捕捉这一时期观测到的太平洋信风增强。根据观测到的太平洋信风增强和厄尔尼诺/南方涛动远缘联系模型，对自由运行的历史模拟进行线性调整，可以解释降水趋势的差异。此外，太平洋信风趋势和区域降水趋势都在具有规定观测海面温度（SST）的气候模拟中得到了再现，突出了热带太平洋 SST 模式的作用。

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来源期刊

npj Climate and Atmospheric Science Earth and Planetary Sciences-Atmospheric Science

CiteScore

8.80

自引率

3.30%

发文量

审稿时长

21 weeks

期刊介绍： npj Climate and Atmospheric Science is an open-access journal encompassing the relevant physical, chemical, and biological aspects of atmospheric and climate science. The journal places particular emphasis on regional studies that unveil new insights into specific localities, including examinations of local atmospheric composition, such as aerosols. The range of topics covered by the journal includes climate dynamics, climate variability, weather and climate prediction, climate change, ocean dynamics, weather extremes, air pollution, atmospheric chemistry (including aerosols), the hydrological cycle, and atmosphere–ocean and atmosphere–land interactions. The journal welcomes studies employing a diverse array of methods, including numerical and statistical modeling, the development and application of in situ observational techniques, remote sensing, and the development or evaluation of new reanalyses.