日食对中国大气边界层热力状态的影响分析

Effects of the solar eclipse on atmospheric boundary layer thermodynamics in China

地球的能量主要来源于太阳,太阳的辐射变化对地球大气边界层有着潜在的影响。日食过程中太阳被遮挡减少了到达地球的热辐射能量,大气热力状态被改变,为研究大气层热力状态的变化提供了一个好的机会。2020年6月21日,在中国境内出现了一次日环食,除日环食带以外中国其他地区都可见到日偏食。为了研究日食对边界层大气热力状态的影响,本文分析了西安、遵义、南宁和宜宾4个不同地区的微波辐射计实时连续观测的大气温湿度廓线数据,研究日食期间不同日面遮挡程度对不同边界层高度上大气热力状态的变化及其受天气条件的影响。这4个站点月球对太阳的遮挡比例都不相同,其中宜宾处在日环食带上遮挡最多。实验结果表明,日食期间大气边界层温湿度受到日食的影响较为明显。从日食开始到最大时刻由于到达地球的太阳辐射能减少,边界层大气温度也开始降低,在日食从最大时刻到结束期间,从太阳到达地球的辐射能量逐渐增大,边界层温度开始上升,日食过程中相对湿度变化与温度相反。4个站点温度变化最大约4℃,相对湿度变化超过10%,水汽密度没有明显变化,各个高度层温湿度变化明显滞后日食过程约15—20 min。日食过程中,月球对日面遮挡越多,日食对边界层大气温湿度廓线的影响也越明显。日食对边界层大气温湿度的影响随着高度的增加逐渐减弱,日面被遮挡的面积越少日食对边界层影响的最大高度也就越低。由于云和雨对太阳辐射的衰减,日食对边界层大气温湿廓线的影响将会减弱。

Earth energy comes from solar radiation,and solar radiation has a potential impact on the atmospheric boundary layer.During the solar eclipse,the solar disk is covered by the moon,and the solar radiation is reduced to reach the Earth,causing cooling in the surface layers of the atmosphere.Solar eclipse provides an ideal condition for studying the response of the atmosphere.On June 21,2020,an annular eclipse occurred in China,and the partial solar eclipse can be seen except for the annular eclipse region.This solar eclipse provides a good opportunity for us to study the variation of the atmospheric thermodynamics.The most important parameter of thermodynamics during solar eclipse is the temperature in the different altitudes in the boundary layer.In this paper,to study the effect of the solar eclipse on atmospheric thermodynamics in the boundary layer,the atmospheric temperature and humidity profiles observed by the Ground-based multichannel Microwave Radiometer(GMR)in Xi’an,Zunyi,Nanning and Yibin,China.The GMR has high spatial resolution and high sensitivity and it is usually used to observe and study the atmospheric temperature and humidity profiles.Therefore,the variation of the atmospheric thermodynamics was studied at different regions and weather conditions by using the GMR during the solar eclipse.At these observation stations,the proportion of the sun covered by the moon is different;the annular eclipse can be observed in Yibin,and the covered proportion is maximum.This paper compared the results of the experiment and the observation results showed that the temperature and humidity profiles of the boundary layer had obviously changed.From the beginning of the solar eclipse to the maximum of the solar eclipse,the temperature of the boundary layer began to decrease because the solar radiation reaching the Earth was reduced.During the period from the maximum solar eclipse to the end of the solar eclipse,the radiation energy from the sun to the earth gradually increased,the temperature of the boundary layer began to rise,the variation in relative humidity was the opposite,the maximum variation in the temperature was approximately 4℃,the relative humidity was more than 10%,and the water vapor density profile had no obvious variation at these stations.The variation in the temperature and humidity lagged behind by approximately 15 to 20 minutes.The effect of the solar eclipse decreases with increasing height for the temperature and humidity in the boundary layer.In the process of the solar eclipse,the greater the solar disk is covered by the moon,the more obvious the effect of the solar eclipse on the temperature and humidity in the boundary layer.Due to the attenuation of solar radiation by clouds and rain,the influence of solar eclipses on the atmospheric temperature and humidity in the boundary layer will be weakened.This observation experiment had provided fine-scale variations of the atmospheric parameters both in time and height by using the GMR during the solar eclipse.These results may have important implications in understanding the response of atmosphere to the thermodynamics perturbations caused by the solar eclipse.