Variability of extreme precipitation events in Tijuana, Mexico
Variability of extreme precipitation events in Tijuana, Mexico
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DOI：
10.3354/cr025229
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发表时间：
2004-01-23
期刊：
影响因子：
1.1
通讯作者：
Rivas, D
中科院分区：
文献类型：
--
作者：
Cavazos, T;Rivas, D
我们调查了 1950 年至 2000 年期间蒂华纳（墨西哥）1 d 极端降水量（前 10%）的变化。年际降雨量变化与厄尔尼诺/南方涛动 (ENSO) 有关，它解释了 30% 的降雨量和 36% 的 1 d 极端降水量变化。降水量年际变化较大，1950-1976年为相对干旱期，变率较小；1976-2000年为相对湿润期，变率较大。所有极端潮湿年份（>1 SD）和最大频率的 1 d 极端事件发生在 1976-1977 年之后，其中 8 个极端潮湿年份中有 6 个以厄尔尼诺事件为特征，2 个以中性条件为特征。然而，1950-2000 年期间超过一半的 1 d 极端事件发生在非 ENSO 年份，这为中性条件对该地区的极端气候变化做出了重大贡献这一事实提供了证据。在中性（强厄尔尼诺）条件下发生的极端事件与“菠萝快车”和“中性太平洋/北美（PNA）”（负热带/北半球[TNH]）遥相关模式有关，该遥相关模式将日期变更线以西（东）的异常热带对流强迫与研究区域上空的强副热带急流联系起来。中性 PNA 是典型 PNA 遥连模式的变体；它向+PNA（典型的厄尔尼诺现象）的西北方向移动，向-PNA（典型的拉尼娜现象）的东南方向移动，其特点是阿拉斯加湾上空有一个强脊，加利福尼亚上空有一个深低压。我们认为，急流槽是中性和强厄尔尼诺年极端事件的典型特征，由于与下加利福尼亚州附近暖加州洋流的区域异常、来自副热带温暖海面区域的低层水汽平流以及研究区域上空的强烈对流活动的热相互作用，进一步加剧了急流槽。
We investigated the variability of 1 d precipitation extremes (top 10%) in Tijuana (Mexico) during 1950-2000. Interannual rainfall variability is associated with El Nino/Southern Oscillation (ENSO), which explains 30 % of rainfall and 36 % of 1 d extreme precipitation variance. Interannual precipitation exhibits a large change, with a relatively dry period and less variability during 1950-1976, followed by a relatively wet period and more variability during 1976-2000. All extremely wet years (>1 SD) and the largest frequency of 1 d extremes occurred after 1976-1977, with 6 out of 8 extremely wet years characterized by El Nino episodes and 2 by neutral conditions. However, more than half of the 1 d extremes during 1950-2000 occurred in non-ENSO years, providing evidence for the fact that neutral conditions contribute significantly to extreme climatic variability in the region. Extreme events that occur in neutral (strong El Nino) conditions are associated with a 'pineapple express' and a 'neutral Pacific/North America (PNA)' (negative tropical/northern hemisphere [TNH]) teleconnection pattern that links an anomalous tropical convective forcing west (east) of the date line with a strong subtropical jet over the study area. The neutral PNA is a variant of the typical PNA teleconnection pattern; it is shifted northwestward of the +PNA (typical of El Nino) and southeastward of the -PNA (typical of La Nina) and is characterized by a strong ridge over the Gulf of Alaska and a deep low over California. We believe that the trough in the jet, typical of extreme events during neutral and strong El Nino years, is further intensified by thermal interaction with regional anomalies of a warm California Current off Baja California, low-level moisture advection from the subtropical warm sea-surface region, and intense convective activity over the study area.