Tropical cloudiness and rainfall related to pressure and tidal variations
Tropical cloudiness and rainfall related to pressure and tidal variations
复制标题
与气压和潮汐变化有关的热带云量和降雨量
DOI：
10.1002/qj.49709540309
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发表时间：
1969
影响因子：
8.9
通讯作者：
J. Simpson
中科院分区：
文献类型：
--
作者：
G. Brier;J. Simpson
热带云量和降雨量与半日太阳潮（S2）之间有明确的统计关系，这表现在半日地面气压变化上。压力和天气数据来自巴达维亚（70年）和威克岛（12年）。S2潮汐效应在日出和日落附近增强云和雨，在正午和午夜之后抑制云和雨。分析的基础是：(a) S2波振幅在月份之间变化15 - 20%，而每天变化超过100%；(b)从一个台站的压力数据计算得到的S2波振幅与上午4 - 5至10点、上午10点至下午4点等时段的5-6小时压力变化密切相关。分析的关键是证明，在这些时间段内，与5-6小时压力变化较小的天数相比，5-6小时压力变化较大的天数在这些时间段内具有较大的云量变化（在上述意义上）。
A definitive statistical relationship is established between tropical cloudiness and rainfall and the semidiurnal solar (S2) atmospheric tide, as manifested in the semi-diurnal surface pressure variation. Pressure and weather data are used from Batavia (seventy years) and Wake Island (twelve years). The S2 tidal effect is shown to enhance cloudiness and rain near sunrise and sunset, and to suppress them shortly after midday and midnight. The analysis is based on (a) the fact that the S2 amplitude varies by 15–20 per cent between months and by more than 100 per cent from day to day and (b) the amplitude of the S2 wave as computed from the pressure data at a station is closely related to the 5–6 hourly pressure changes during the periods around 4–5 a.m. to 10 a.m., from 10 a.m. to 4 p.m., etc. The crux of the analysis is the demonstration that days with large 5–6 hourly pressure changes during these periods have large cloudiness changes (in the sense described above) during these same periods relative to days with small 5–6 hourly pressure changes.
Possible mechanistic connections between S2 pressure tendencies and cloud properties are examined. The varying convergence-divergence field is suggested as the main link. It is shown how the concentration of active cloud updraughts in the Tropics can permit cloudiness to be extremely sensitive to small divergence fields.
Finally, large-scale simultaneous pressure changes over the Pacific Ocean area are shown and related to cloudiness changes. A need for re-examination of the nature and origins of tropical disturbances is shown to exist, using the concept that possible small (terrestrial or extra-terrestrial) triggers may set off significant changes in weather both locally and on the synoptic and global scales.