Transient regional climate change: analysis of the summer climate response in a high-resolution, century-scale, ensemble experiment over the continental United States.
Transient regional climate change: analysis of the summer climate response in a high-resolution, century-scale, ensemble experiment over the continental United States.
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DOI：
10.1029/2011jd016458
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发表时间：
2011-12-27
影响因子：
--
通讯作者：
Scherer M
中科院分区：
文献类型：
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作者：
Diffenbaugh NS;Ashfaq M;Scherer M
要将气候变化的潜在影响纳入政策和规划决策，就需要对响应全球辐射强迫的短暂变化而可能出现的次区域气候变化进行量化。在这里，我们报告了高分辨率、世纪尺度的美国气候综合模拟的结果，该模拟是由排放情景特别报告（SRES） A1B情景的大气成分浓度所强迫的。我们发现，在美国大陆的大多数地区，21世纪夏季变暖永久性地出现在2020年之前的基线年尺度变率之外。永久性地出现在基线年尺度变率之外显示出更大的空间异质性，在美国西南部地区出现在2030年之前。强劲的夏季变暖出现的模式与夏季变暖幅度的模式形成对比，夏季变暖幅度在美国中部最大，在美国西部最小。除了更强的变暖，美国中部还表现出地表气温、降水、水分和能量通量变化的更强耦合。随着大气环流的变化，对流层中反气旋异常增加，中纬度高空急流向极地移动。然而，作为基线变率的一部分，美国中部的短暂变暖小于美国西南部或东北部的变暖，我们与观测资料和耦合模式比对项目第3阶段（CMIP3）全球气候模式实验集合的比较表明，近期全球变暖可能会在基线变率相对较小的地区造成强劲的次区域尺度变暖。相反，在基线气候动力学变异性较大的地方，对温室强迫升高的响应也可能有较大的变异性，从而降低了瞬态变暖信号的稳健性。
Integrating the potential for climate change impacts into policy and planning decisions requires quantification of the emergence of sub-regional climate changes that could occur in response to transient changes in global radiative forcing. Here we report results from a high-resolution, century-scale, ensemble simulation of climate in the United States, forced by atmospheric constituent concentrations from the Special Report on Emissions Scenarios (SRES) A1B scenario. We find that 21st century summer warming permanently emerges beyond the baseline decadal-scale variability prior to 2020 over most areas of the continental U.S. Permanent emergence beyond the baseline annual-scale variability shows much greater spatial heterogeneity, with emergence occurring prior to 2030 over areas of the southwestern U.S., but not prior to the end of the 21st century over much of the southcentral and southeastern U.S. The pattern of emergence of robust summer warming contrasts with the pattern of summer warming magnitude, which is greatest over the central U.S. and smallest over the western U.S. In addition to stronger warming, the central U.S. also exhibits stronger coupling of changes in surface air temperature, precipitation, and moisture and energy fluxes, along with changes in atmospheric circulation towards increased anticylonic anomalies in the mid-troposphere and a poleward shift in the mid-latitude jet aloft. However, as a fraction of the baseline variability, the transient warming over the central U.S. is smaller than the warming over the southwestern or northeastern U.S., delaying the emergence of the warming signal over the central U.S. Our comparisons with observations and the Coupled Model Intercomparison Project Phase 3 (CMIP3) ensemble of global climate model experiments suggest that near-term global warming is likely to cause robust sub-regional-scale warming over areas that exhibit relatively little baseline variability. In contrast, where there is greater variability in the baseline climate dynamics, there can be greater variability in the response to elevated greenhouse forcing, decreasing the robustness of the transient warming signal.