Energetics of southeastern Pacific cut-off lows
Energetics of southeastern Pacific cut-off lows
复制标题
东南太平洋截止低点的能量
DOI：
10.1007/s00382-015-2779-7
复制
发表时间：
2016
期刊：
影响因子：
4.6
通讯作者：
E. D. Piva
中科院分区：
文献类型：
--
作者：
M. Gan;E. D. Piva
南太平洋和南美洲上空截止低压（COL）的存在通常与不利天气事件有关，例如南美洲中部地区的强降水、巴西南部的霜冻以及安第斯山脉背风气旋和巴西南部海岸的强烈气旋的发展。尽管如此重要，但 COL 的形成和维持机制尚不清楚。本研究的目的是详细说明东南太平洋上空形成的 50 个 COL 的涡动能方程的显着变化。只有那些在海洋上空形成并在其一生中大部分时间都停留在那里的 COL 案例才会被选中。方程的主要项[地转通量收敛（AFC）、斜压转换（BRC）和正压转换（BRT）]是使用国家环境预测中心/能源再分析部的每6小时网格数据计算的。 COL的形成机制与BRC和AFC有关。在中年期间，BRC 项将涡流动能转换为涡流势能，并且 AFC 直到中年点后 6 小时为止都具有正贡献。在耗散阶段，BRC项保持正值，AFC项变为负值。 BRT 在整个生命周期中从 COL 中提取动能。 AFC项在截止寿命的所有阶段中都是最重要的，它负责延长截止寿命，而其他项都是负数。
The existence of cut-off lows (COLs) over South Pacific and South America is often associated with adverse weather events such as intense precipitation over the central region of South America, frost episodes in southern Brazil and the development of Andes lee cyclones and intense cyclones over the southern coast of Brazil. Despite this importance, the formation and maintenance mechanisms of the COLs are not well understood. To detail the significant variability in terms of the eddy kinetic energy equation for fifty cases of COLs that formed over the southeastern Pacific Ocean is the aim of this study. Only the cases of COLs that formed over the ocean and remained there during most of their life were chosen. The main terms of the equation [ageostrophic flux convergence (AFC), baroclinic conversion (BRC) and barotropic conversion (BRT)] were calculated using the 6-hourly gridded data from the National Centers for Environmental Prediction/Department of Energy reanalysis. The formation mechanism of the COLs was associated with BRC and AFC. During the midlife period, the BRC term converted eddy kinetic energy to eddy potential energy and the AFC had a positive contribution until 6 h after the midlife point. In the dissipation phase, the BRC term remained positive and AFC became negative. The BRT extracted kinetic energy from the COL during the entire life cycle. The AFC term was the most important in all phases of the cut-off lifetime, and it was the responsible for extending the cut-off lifetime while the others terms were negatives.