Abstract The Annular Solar Eclipse (ASE) occurred on December 26, 2019, which was visible at most of the South Indian subcontinents with greater than 80% obscurity, particularly during the morning hours, and it played a crucial role in the atmospheric dynamics. For the first time, the ground-based measurements have used to investigate the fluctuations of air temperature, relative humidity, atmospheric pressure, wind speed and direction, UV-A radiation, and turbulence parameters on solar eclipse day over a semi-arid region, Anantapur, in Southern India. The Surface Layer (SL) meteorological parameters have abruptly changed on eclipse day (December 26, 2019) as compared to the control day (December 27, 2019). During eclipse day, the near-surface air temperature was significantly decreased (1.12 °C), and relative humidity increased (14.63%) after 60 min of the beginning of the eclipse, which mainly due to cooling the surface. The atmospheric pressure has reduced by 0.9 hPa during the eclipse period, and the winds speed also reduced to 0.92 ms−1 due to the stabilization of Atmospheric Boundary Layer (ABL) and cooling in the SL. The turbulence parameters, including those are Sensible Heat Flux (SHF), Momentum Flux (MF), and Turbulent Kinetic Energy (TKE) have also reduced from 99.37 to 0.91 Wm-2, 0.38 to 0.03 Nm−2, and 1.47 to 0.37 m2s-2, respectively during the eclipse day, which mainly due to eclipse cooling effect diminishing the turbulence in Atmospheric Surface Layer (ASL). The lowest values (0.18 ms−1) of friction velocity were observed during the eclipse day, and the Monin–Obukhov stability parameter showed a significant variation in the atmospheric from weakly unstable to neutral conditions during the eclipse day. The vertical wind speed showed downdrafts during the eclipse and even after the eclipse due to subsidence of air. The investigation revealed that the ABL dynamic process and turbulence processes are affected due to cut off of solar radiation and make the SL cooling.

中文翻译：

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2019 年 12 月 26 日印度南部半干旱地区 Anantapur 日环食期间大气表层特征的扰动

摘要 环日食（ASE）发生在 2019 年 12 月 26 日，在南印度次大陆的大部分地区都可以看到，其模糊度超过 80%，尤其是在早上，它在大气动力学中发挥了至关重要的作用。地面测量首次用于研究半干旱地区日食日气温、相对湿度、大气压力、风速和风向、UV-A 辐射和湍流参数的波动，印度南部的阿南塔普尔。与对照日（2019年12月27日）相比，日食日（2019年12月26日）的表层（SL）气象参数发生了突变。在日食日，近地表气温显着降低（1.12 °C），相对湿度增加（14. 63%) 在日食开始 60 分钟后，主要是由于表面冷却。由于大气边界层（ABL）的稳定和SL的冷却，日食期间大气压力降低了0.9 hPa，风速也降低到0.92 ms-1。湍流参数，包括显热通量 (SHF)、动量通量 (MF) 和湍流动能 (TKE) 也从 99.37 降至 0.91 Wm-2、0.38 至 0.03 Nm-2 和 1.47 至 0.37 m2s -2，分别在日食日期间，这主要是由于日食冷却效应减少了大气表面层（ASL）的湍流。在日食期间观察到摩擦速度的最低值 (0.18 ms-1)，Monin-Obukhov 稳定性参数表明，在日食日期间，大气从弱不稳定到中性条件发生了显着变化。由于空气下沉，在日食期间甚至日食之后，垂直风速显示出下降气流。调查表明，ABL 动力过程和湍流过程因太阳辐射的切断而受到影响，使 SL 冷却。