摘要:利用ERA-Interim逐日再分析资料，使用EOF（Empirical Orthogonal Function）等统计方法，分析了中国低纬地区平流层准零风层（Quasi-Zero Wind Layer，QZWL）的时空分布特征，旨在为平流层飞艇寻找合适的运行区域及时段。低纬地区QZWL主要受到热带平流层大气环流季节性变化和平流层准两年振荡（Quasi-BiennialOscillation，QBO）的影响。在二者共同作用下，低纬地区QZWL高概率带可分为南北两支：“北支”出现在10月至次年4月间，QBO东风位相时期，“北支”中心纬度基本维持在20°N附近，西风位相时期，“北支”中心纬度随高度降低南移明显；“南支”仅出现在QBO西风位相期间，5~11月在5°N附近，其余时段与“北支”合并，可以认为是“北支”向南延伸。通过对比海口站和南沙站Weibull概率密度函数与风速资料的拟合结果，表明Weibull分布可以很好拟合不同QBO位相下平流层逐月风速频率分布，根据Weibull分布计算特定的累积概率风速值，可以作为选取适宜平流层飞艇运行的低风速风场的判据。海口站30~50 hPa高度11月至次年4月、南沙站50~70 hPa高度QBO西风位相时期全年均较为适合平流层飞艇运行。
关键词:低纬地区/
平流层准零风层/
平流层飞艇/
Weibull分布
Abstract:In order to find suitable airspace for the stratospheric airship, the characteristics of spatial-temporal distribution of the stratospheric Quasi-Zero Wind Layer (QZWL) in low-latitude regions are analyzed using the EOF (Empirical Orthogonal Function) method and based on the ERA-Interim daily reanalysis data. The QZWL is mainly influenced by the stratospheric seasonal transition and the Quasi-Biennial Oscillation (QBO), and can be classified into two categories. The northern type of QZWL occurs at 20°N from October to April, while the southern type of QZWL occurs all year round during the westerly QBO phase. The southern type of QZWL is located at around 5°N from May to November and merged with the northern type in the remaining time. Monthly statistical modeling studies in different QBO phases indicate that the probability density function of Weibull distribution fits well wind speed data collected at Haikou station and Nansha station. The specific probability distribution of wind speed predicted by the Weibull distribution and cumulative function can be used to determine suitable airspace for the stratospheric airship. As a result, the airspace at the height between 50 hPa and 30 hPa from October to April at Haikou station and at the height between 70 hPa and 50 hPa for the whole year in the westerly QBO phase at Nansha station are suitable for the stratospheric airship to make smooth flight.
Key words:Low-latitude regions/
Stratosphere quasi-zero wind layer/
Stratosphere airship/
Weibull distributions
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