New Insights into the South American Low-Level Jet from RELAMPAGO Observations
New Insights into the South American Low-Level Jet from RELAMPAGO Observations
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DOI：
10.1175/mwr-d-21-0161.1
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发表时间：
2022-02
影响因子：
3.2
通讯作者：
C. Sasaki;A. Rowe;L. McMurdie;K. Rasmussen
中科院分区：
文献类型：
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作者：
C. Sasaki;A. Rowe;L. McMurdie;K. Rasmussen
基于自适应地面观测的电气化、闪电和中尺度/微尺度过程遥感（RELAMPAGO）项目对阿根廷中部的南美低空急流（SALLJ）进行了无与伦比的观测，在急流路径和快速增长的对流上游进行了高时间观测。喷气机的垂直和时间结构是通过在sierra de Córdoba （SDC）附近的两个固定地点每3小时发射一次的探测以及高分辨率的再分析数据来表征的。目的将SALLJ识别标准应用于每次探测，以确定射流的存在、时间和垂直特征。观测结果在很大程度上证实了先前的结果，即sallj最频繁地来自北方，发生在夜间，并且在低水平达到峰值，尽管llj在RELAMPAGO期间持续时间较长的事件结束时明显达到峰值。该研究将sallj分为两类：持续时间较短的事件，射流核心在夜间达到峰值，处于低水平；持续时间较长的事件，射流在接近周期结束时升高，缺乏明确的日循环。在持续时间较短的事件中观测到边界层过程和大尺度强迫的证据，而在持续时间较长的5-6天事件中，天气强迫占主导地位。在5-6天SALLJ事件结束时，SDC以东的水汽量和对流覆盖面积最大。
The Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) campaign produced unparalleled observations of the South American Low-Level Jet (SALLJ) in Central Argentina with high temporal observations located in the path of the jet and upstream of rapidly growing convection. The vertical and temporal structure of the jet is characterized using 3-hourly soundings launched at two fixed sites near the Sierras de Córdoba (SDC), along with high-resolution reanalysis data. Objective SALLJ identification criteria are applied to each sounding to determine the presence, timing, and vertical characteristics of the jet. The observations largely confirm prior results showing that SALLJs most frequently come from the north, occur overnight, and peak in the low levels, though LLJs notably peaked higher near the end of longer duration events during RELAMPAGO. This study categorizes SALLJs into shorter duration events with jet cores peaking overnight in the low levels and longer 5-6-day events with elevated jets near the end of the period that lack a clear diurnal cycle. Evidence of both boundary layer processes and large-scale forcing were observed during shorter duration events, whereas synoptic forcing dominated the longer 5-6-day events. The highest amounts of moisture and larger convective coverage east of the SDC occurred near the end of the 5-6-day SALLJ events.