Precipitation structure in the Sierra Nevada of California during winter
Precipitation structure in the Sierra Nevada of California during winter
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加利福尼亚州内华达山脉冬季降水结构
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
K. Georgakakos
中科院分区：
文献类型：
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作者：
G. Pandey;D. Cayan;K. Georgakakos
本文研究了内华达州山区冬季（11 - 4月）降水中沿着加州海岸的高空特征的影响。在内华达州山脉地区的降水事件主要发生在冬季，无论站的位置（背风或迎风）和海拔。该地区的大多数降水事件与潮湿的西南风（来自西南方向）有关，并且往往发生在逆风方向的700毫巴温度接近−2°C时。这种有利的风向和温度表明，在增加该地区的降水的水分输送和地形抬升的重要性。通过利用所观察到的依赖性的降水上层空气条件下，一个线性模型，制定量化的降水观测在不同的网站作为一个功能的水分输送。该模型的技能随着聚集的时间尺度而增加，在5-7天的聚集期内达到50%以上的方差。这表明，上游空气水分输送可以用来估计在内华达州山脉地区的降水总量。
Influences of upper air characteristics along the coast of California upon winter-time (November-April) precipitation in the Sierra Nevada are investigated. Precipitation events in the Sierra Nevada region occur mostly during wintertime, irrespective of station location (leeside or windside) and elevation. Most precipitation episodes in the region are associated with moist southwesterly winds (coming from the southwest direction) and also tend to occur when the 700-mbar temperature at the upwind direction is close to −2°C. This favored wind direction and temperature signify the importance of both moisture transport and orographic lifting in augmenting precipitation in the region. By utilizing the observed dependency of the precipitation upon the upper air conditions, a linear model is formulated to quantify the precipitation observed at different sites as a function of moisture transport. The skill of the model increases with timescale of aggregation, reaching more than 50% variance explained at an aggregation period of 5–7 days. This indicates that upstream air moisture transport can be used to estimate the precipitation totals in the Sierra Nevada region.