Climatic and synoptic characterization of heat waves in Brazil
Climatic and synoptic characterization of heat waves in Brazil
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DOI：
10.1002/joc.5294
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发表时间：
2018-03-30
期刊：
影响因子：
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通讯作者：
Palmeira, Ana Cristina
中科院分区：
文献类型：
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作者：
Geirinhas, Joao L.;Trigo, Ricardo M.;Palmeira, Ana Cristina
根据最新的全球和区域环流模式，在大多数气候情景下，在未来几十年内，发生大热浪（HWs）的概率，如2003年欧洲或2010年俄罗斯事件将显着增加。目前，有许多研究北方半球的特征HWs和评估其在公共卫生，经济和农业等几个领域的影响。然而，在南美洲，特别是巴西，尽管其地理范围很大，并且可能影响众多人口，但缺乏类似的分析。在这里，我们进行评估的HW事件和特征记录在六个大的巴西城市在过去的五十年。所进行的分析表明，自20世纪80年代以来，HW频率存在积极和显着的趋势，特别是圣保罗，马瑙斯和累西腓的城市。在过去的几十年里，巴西利亚是在HW制度下每年记录天数最多的城市，而里约热内卢则记录了最低值。与夏季HWS相关的大尺度大气环流模式的评估表明，波尔图阿莱格雷、圣保罗、里约热内卢和巴西利亚存在明显的同心和正的500 hPa位势高度异常，随后是正的850 hPa温度异常。这些异常可能与准静止反气旋系统有关，这些系统是由南大西洋副热带高压系统的异常向西移引起的，而南大西洋副热带高压系统的异常西移与其他瞬变（和非瞬变）系统（如热带辐合带（ITCZ）和南大西洋辐合带）的减弱有关。对于马瑙斯，已确定的异常与ITCZ的北移有关。这种结构与太阳辐射模式的增加和土壤湿度的减少是一致的，从而提高了表面温度值，这可能与土壤和大气之间的正反馈机制有关。
According to the latest global and regional circulation models, the probability of occurrence of large heat waves (HWs), such as the 2003 European or the 2010 Russian events will increase significantly in the following decades under most climate scenarios. Currently, there are numerous studies for the Northern Hemisphere characterizing HWs and evaluating their impacts in several areas such as public health, economy, and agriculture. However, over South America, and in particular for Brazil, similar analysis is lacking despite its large geographical extension and numerous population potentially affected. Here we perform an assessment of HW events and characteristics recorded in six large Brazilian cities during the last five decades. The performed analysis reveals the existence of positive and significant trends in HW frequency since the 1980s, particularly for the cities of SAo Paulo, Manaus, and Recife. Over the last decades, Brasilia was the city that recorded the highest number of days per year under a HW regime, contrasting with Rio de Janeiro that recorded the lowest value. The assessment of the large-scale atmospheric circulation patterns associated with summer HWs, indicated for Porto Alegre, SAo Paulo, Rio de Janeiro, and Brasilia the presence of well-marked concentric and positive 500 hPa geopotential height anomalies followed by positive 850 hPa temperature anomalies. These anomalies are likely associated with quasi-stationary anticyclonic systems promoted by anomalous westward displacements of the South Atlantic Subtropical High System which are related to a weakening of other transients (and non-transient) systems such the Intertropical Convergence Zone (ITCZ) and the South Atlantic Convergence Zone. For Manaus, the identified anomalies are linked to a northward displacement of the ITCZ. This configuration is compatible with an increase in solar radiative pattern and decreased soil moisture, enhancing surface temperature values, possibly associated with positive feedback mechanisms between soil and the atmosphere.