The climate of Madras during the eighteenth century
The climate of Madras during the eighteenth century
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十八世纪马德拉斯的气候
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Stefan Militzer
中科院分区：
文献类型：
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作者：
R. Walsh;R. Glaser;Stefan Militzer
德国-丹麦传教士基金会的档案，包括 1732 年至 1737 年和 1789 年至 1791 年的两本马德拉斯天气日记以及年度报告和信件，被用来重建印度东南部马德拉斯地区在 18 世纪的气候状况。根据日记中降雨发生和风向日变化的记录，可得出记录的每个月 08:00 和 17:00 的降雨日数和风向频率。每个雨天降雨量的现代数据用于将雨量数据转换为每月降雨量的估计值。陆风（08:00 h）和海风（17:00 h）时的风向数据分别用作东北季风（10-12月雨季）和夏季西南季风强度的指标。结果表明，1732年至1737年（也可能是1720年代）的年降雨量比1813年至1991年的平均降雨量低约27%，东北季风降雨量非常低（-41%），但西南季风降雨量接近平均水平。风向数据显示西南季风和东北季风都比正常强。相比之下，1789-1791 年的估计年降雨量接近平均水平，但西南季风降雨比平均水平低 54%，东北季风降雨比平均水平高 22%。这似乎与 1732 年至 1737 年相比减弱的东北季风和西南季风有关。 1740 年至 1788 年期间似乎比 1720 年代和 1730 年代更加湿润。除1740年代和1780年代外，热带气旋频率较低。 1730 年代的干旱期恰逢欧洲异常温暖的冬季。版权所有 © 1999 英国皇家气象学会
Archives of a German–Danish missionary foundation, including two weather diaries for Madras covering the years 1732–1737 and 1789–1791 and annual reports and letters, are used to reconstruct aspects of the climate of the Madras region of SE India during the eighteenth century. Records of rainfall occurrence and diurnal variations in wind direction in the diaries are used to derive the number of raindays and wind direction frequencies at 08:00 and 17:00 h for each month of record. Modern data on rainfall per rainday are used to convert rainday data to estimates of monthly rainfall. Wind direction data at times of land breeze (08:00 h) and sea breeze (17:00 h) are used as indices of the strength of the NE monsoon (in the October–December rainy season) and summer SW monsoon, respectively. Results suggest that annual rainfall in the period 1732–1737 (and probably also the 1720s) was about 27% below the 1813–1991 average, with very low NE monsoon (−41%) but near-average SW monsoon rainfall. The wind direction data suggest that both the SW monsoon and NE monsoon were stronger than normal. In contrast, estimated annual rainfall in 1789–1791 was near-average, but with SW monsoon rain 54% below average and NE monsoon rain 22% above average. This appears to be linked to less strong NE and SW monsoon winds than in 1732–1737. The period 1740–1788 appears to have been considerably wetter than the 1720s and 1730s. Tropical cyclone frequency was low except in the 1740s and 1780s. The 1730s dry period coincided with a period of anomalously warm winters in Europe. Copyright © 1999 Royal Meteorological Society