台风条件下火箭探测气象数据与ERA5再分析资料的对比分析

Comparative Analysis of Sounding Rocket Data and ERA5 Reanalysis Data Under Typhoon Conditions

关键词:  ERA5  台风  火箭  温度  相对湿度  风速

Key words:  ERA5  typhoon  rocket  temperature  relative humidity  wind speed

摘要:

再分析资料的准确性对台风等灾害性天气预报及研究有着重要价值。以往缺乏在强台风条件下平流层内的直接观测资料，使得无法对再分析资料的准确性进行验证，基于新型火箭探测数据对 ERA5 再分析数据的气象要素在强台风条件下进行对比分析。(1) 台风条件下三次试验ERA5与火箭探测在对流层内的温度廓线几乎重合，15 km 以下两者之间的误差不到 1 ℃，但 15 km 以上的平流层两者偏差随高度增加而增大，ERA5比火箭探测的温度明显偏低，在 15～20 km、20～30 km、30～40 km 和 40 km 以上两者偏差平均值分别为3.75 ℃、5.52 ℃、14.41 ℃和 19.25 ℃；(2) 相对湿度三次试验两者的变化趋势还是比较相似的，但在平流层低层15～20 km 两者存在较大差异，火箭探测相对湿度在 15 km 左右是上干下湿分界高度，而 ERA5 的分界高度抬升到 20 km 以上，也就是说 ERA5把高湿度层抬升了 5 km 以上；值得一提的是 25 km 以上，台风影响前，两者相对湿度都几乎接近 0%，而在台风影响期间火箭探测相对湿度可达 5% 左右，ERA5 相对湿度仍然几乎为 0%；(3)台风条件下三次试验风速廓线显示两者在平流层低层到对流层变化趋势十分相似，相关系数可达 0.85左右，平均偏差大约为 2 m·s-1；而在平流层中高层相似度降低，偏差增大，相较于火箭探空，ERA5 风速偏低 4 m·s-1左右。

Abstract:

The accuracy of reanalysis data is crucial for numerical model predictions and stratospheric studies. However, there is a lack of direct observational data in the stratosphere during strong typhoon conditions. This study compares meteorological parameters under strong typhoon conditions using ERA5 reanalysis data and a new type of sounding rocket data. The findings are as follows: (1) Temperature profiles in the troposphere for the three typhoon experiments are nearly identical between ERA5 and sounding rocket data. The mean error between the two datasets is less than 1 ℃ below 15 km. However, as altitude increases in the stratosphere, the deviation between ERA5 and sounding rocket data becomes more significant. ERA5 consistently shows lower temperatures compared to the sounding rocket data. The mean deviations between ERA5 and rocket data are 3.75 ℃ , 5.52 ℃ , 14.41 ℃ , and 19.25 ℃ in the altitude ranges of 15~20 km, 20~30 km, 30~40 km, and above 40 km, respectively. (2) Regarding relative humidity, both datasets exhibit similar trends. However, there is a notable difference in the lower stratosphere (15~20 km). According to the sounding rocket data, the boundary altitude for dry and humid air is around 15 km, while ERA5 suggests this boundary is above 20 km. It is worth mentioning that both datasets show that relative humidity above 25 km is close to 0% before the typhoon’s impact. During the typhoon’s impact, the sounding rocket data indicates relative humidity can reach up to 5%, whereas ERA5 still shows relative humidity close to 0%. (3) Wind speed profiles during the three typhoon experiments demonstrate high similarity and correlation coefficients of approximately 0.85 in the troposphere and lower stratosphere. The average deviation is around 2 m · s -1. However, as altitude increases in the middle and upper stratosphere, the similarity decreases, and the deviation increases. ERA5 consistently shows wind speeds approximately 4 m·s -1 lower than the sounding rocket data.