ABSTRACT

Transient alterations in the surface meteorological parameters and atmospheric boundary layer (ABL) due to annual solar eclipse occurred on 26 December 2019 have been investigated using collocated ground-based remote-sensing and in situ measurements over a tropical rural station, Gadanki (13.5 ºN, 79.2 ºE). This event had provided an opportunity to assess the eclipse effect on atmospheric parameters as it occurred during initial hours of the boundary layer evolution (between 08:07 IST and 11:15 IST with peak at 09:32 IST over Gadanki). As eclipse commenced, the observations showed a dramatic reduction in the incoming shortwave radiation and consequent changes in air temperature and wind patterns throughout the ABL. Nevertheless, the amplitude of the changes in various parameters is not analogous to the obscuration proportions but is significantly dictated by the background meteorological conditions such as prevalence of dense fog and cloudiness during the eclipse timings. Ceilometer and wind profiler observations have provided the high-resolution continuous signatures of clouds and fog, strong subsidence, thick layers above the ABL, and a clear change in ABL height (ABLH) during the eclipse epoch. Interestingly, the delay in the evolution of ABL due to the eclipse is clearly manifested. The ABLH, which remained shallow even after the eclipse peak, has shown a rapid increase by more than 1000 m within a short span of an hour just before and after the eclipse culmination. However, significant delay (of about 2 hours after the eclipse) is observed in the surface variables to fall in the range of their climatological values. The observations elusively suggest that commence and termination phases of eclipse analogously influenced the surface and boundary layer parameters in descending sequence (eclipse effect is subtly seen first in Ceilometer and wind profiler attributes followed by surface state variables).

摘要

已使用并置地基遥感和原位遥感调查了由 2019 年 12 月 26 日发生的年度日食引起的地表气象参数和大气边界层 (ABL) 的瞬态变化在热带乡村站 Gadanki（13.5 ºN，79.2 ºE）上进行的测量。这一事件提供了一个机会来评估日食对大气参数的影响，因为它发生在边界层演化的最初几个小时（在 IST 08:07 和 11:15 IST 之间，在 09:32 IST 在 Gadanki 上达到峰值）。随着日食的开始，观测显示传入的短波辐射急剧减少，随后整个 ABL 的气温和风模式发生了变化。然而，各种参数的变化幅度并不类似于遮蔽比例，而是受背景气象条件的显着影响，例如日食期间的浓雾和多云。云高仪和风廓线仪观测提供了云和雾、强烈沉降、ABL 上方的厚层以及日食时期 ABL 高度 (ABLH) 的明显变化的高分辨率连续特征。有趣的是，由于日食导致 ABL 演化的延迟很明显。即使在日食高峰期之后仍保持较浅的 ABLH，在日食高峰期前后的短短 1 小时内迅速增加了 1000 多米。然而，在地表变量中观察到显着延迟（日食后约 2 小时），以落入其气候值范围内。