Effects of atmospheric river landfalls on the cold season precipitation in California
Effects of atmospheric river landfalls on the cold season precipitation in California
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DOI：
10.1007/s00382-012-1322-3
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发表时间：
2012
期刊：
影响因子：
4.6
通讯作者：
Jinwon Kim;D. Waliser;P. Neiman;B. Guan;Ju-Mee Ryoo;G. Wick
中科院分区：
文献类型：
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作者：
Jinwon Kim;D. Waliser;P. Neiman;B. Guan;Ju-Mee Ryoo;G. Wick
利用2001-2010年10个水年（WYs）的观测数据和区域模型，结合基于遥感和再分析的可降水量（PWV）目视检查的大气河流（AR）登陆清单，研究了加州海岸AR登陆对加州冷季降水的影响。SSM/I和SSMIS反演的PWV和ERA中期再分析显示，加州海岸有95个AR登陆日，这些日在37.5 N的北方和南方海岸之间几乎均匀分布。CPC/NCEP网格化日降水分析表明，加州冷季降水总量的10-30%发生在这些AR登陆期间。分析还表明，AR在加州登陆期间的降水量和降水强度具有明显的南北梯度。这种南北对比的AR降水是逆转的非AR降水在沿海范围。AR登陆的频率和冷季降水总量在塞拉利昂内华达州地区只有轻微相关。相反，AR登陆与强降水事件的发生密切相关。冻结层高度系统性地高于AR潮湿的日子比非AR潮湿的日子，这表明在AR风暴的低对流层温暖。对2001-2010年10个工作年的冷季模拟表明，天气研究与预报（WRF）模式可以合理地模拟季节和AR降水总量的重要特征。模拟结果与ERA-Interim高空场的日型相关系数在大部分时间都超过0.9。这表明模拟的大气环流时间变化与季节时间尺度上的再分析合理一致，这些特征对于可靠地模拟区域尺度水文循环至关重要。模拟的季节性和AR降水总量也与CPC/NCEP降水分析相当一致。最显着的模式误差包括高估（低估）的季节总和AR降水在北方（南部）加州地区。在模拟过程中的AR和非AR湿天冻结高度的差异同意从ERA中期再分析。在模拟中，冻结高度被系统性地高估了，这表明对流层低层存在暖偏差。总体而言，WRF似乎表现出合理的模拟与AR登陆相关的冷季降水的关键功能，评估全球气候变化和变化对未来加州水文的影响的重要能力。
Effects of atmospheric river (AR) landfalls in the California coast on the cold-season precipitation in California are examined for the cold seasons of 10 water years (WYs) 2001–2010 using observed data and regional modeling in conjunction with AR-landfall inventory based on visual inspections of precipitable water vapor (PWV) from remote sensing and reanalysis. The PWV in the SSM/I and SSMIS retrievals and the ERA-Interim reanalysis shows 95 AR-landfall days in the California coast that are almost evenly split between the northern and southern coasts across 37.5N. The CPC/NCEP gridded daily precipitation analysis shows that 10–30% of the cold-season precipitation totals in California have occurred during these AR landfalls. The analysis also reveals that the percentage of precipitation and the precipitation intensity during AR landfalls in California are characterized by strong north-to-south gradient. This north–south contrast in the AR precipitation is reversed for the non-AR precipitation in the coastal range. The frequency of AR landfalls and the cold-season precipitation totals in the Sierra Nevada region are only marginally correlated. Instead, AR landfalls are closely related with the occurrence of heavy precipitation events. The freezing-level altitudes are systematically higher for AR wet days than non-AR wet days indicating warmer low-troposphere during AR storms. Cold season simulations for the 10 WYs 2001–2010 show that the Weather Research and Forecast (WRF) model can reasonably simulate important features in both the seasonal and AR precipitation totals. The daily pattern correlation coefficients between the simulated and ERA-Interim upper-air fields exceed 0.9 for most of the period. This suggests that the simulated temporal variations in the atmospheric circulation agree reasonably with the reanalysis over seasonal time scales, characteristics critical for reliable simulations of regional scale hydrologic cycle. The simulated seasonal and AR precipitation totals also agree reasonably with the CPC/NCEP precipitation analysis. The most notable model errors include the overestimation (underestimation) of the season-total and AR precipitation in the northern (southern) California region. The differences in the freezing-level altitudes during the AR- and non-AR wet days in the simulation agree with those from the ERA-Interim reanalysis. The freezing level altitudes are systematically overestimated in the simulations, suggesting warm biases in the low troposphere. Overall, WRF appears to perform reasonably in simulating the key features in the cold season precipitation related with AR landfalls, an important capability for assessing the impact of global climate variations and change on future hydrology in California.