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| DOI | 10.1175/JCLI-D-23-0522.1 |
| The Southern African Heat Low: Structure, Seasonal and Diurnal Variability, and Climatological Trends | |
| 发表日期 | 2024 |
| ISSN | 0894-8755 |
| EISSN | 1520-0442 |
| 起始页码 | 37 |
| 结束页码 | 10 |
| 卷号 | 37期号:10 |
| 英文摘要 | Heat lows are key features of subtropical climates and monsoon systems. In southern Africa, they are pivotal to understanding divergent climate change projections, in particular the veracity of future rainfall decline. Compared to other heat lows, including in West Africa and Australia, the southern African heat low remains poorly documented. Here, we analyze the diurnal cycle, seasonal variability, and trends of the heat low in reanalysis data. In ERA5, 462 strong heat low days are detected between September and March from 1990 to 2019, equating to 7.3% of days sampled. These events feature ascent (exceeding 2 0.2 Pa s 21 ) at low levels (strongest between 800 and 600 hPa) and subsidence aloft, generating low-level cyclonic fl ow with anticyclonic fl ow above. This fl ow exhibits strong diurnal variability, with peak windspeeds between 0600 and 0900 UTC and maximum ascent at - 2300 UTC. Heat lows form preferentially over Angola in September ( - 14 degrees S) and October (15 degrees - 20 degrees S), and in Namibia from November to March ( - 20 degrees - 26 degrees S). Strongest ascent occurs over areas of high elevation. Finally, we show a rapidly increasing frequency of strong heat low days, with a 175% increase between 1960 - 89 and 1990 - 2019. The greatest increase (459%) has occurred in the early summer months of September and October, consistent with projections of delayed rainfall onset. Strikingly, more strong heat lows are detected in the most recent 5 years of analysis (2014 - 19) than in the 30-yr period from 1960 to 1989. These results suggest the heat low is an important feature in determining drying trends over southern Africa and is a vital indicator of climate model accuracy. |
| 英文关键词 | Atmospheric circulation; Climate change; Reanalysis data |
| 语种 | 英语 |
| WOS研究方向 | Meteorology & Atmospheric Sciences |
| WOS类目 | Meteorology & Atmospheric Sciences |
| WOS记录号 | WOS:001223570600001 |
| 来源期刊 | JOURNAL OF CLIMATE
 |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/290447 |
| 作者单位 | University of Oxford |
| 推荐引用方式 GB/T 7714 | . The Southern African Heat Low: Structure, Seasonal and Diurnal Variability, and Climatological Trends[J],2024,37(10). |
| APA | (2024).The Southern African Heat Low: Structure, Seasonal and Diurnal Variability, and Climatological Trends.JOURNAL OF CLIMATE,37(10). |
| MLA | "The Southern African Heat Low: Structure, Seasonal and Diurnal Variability, and Climatological Trends".JOURNAL OF CLIMATE 37.10(2024). |
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