Revisiting Environmental Wind and Moisture Calculations in the Context of Tropical Cyclone Intensification

IF 3 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Forecasting Pub Date : 2023-08-23 DOI:10.1175/waf-d-23-0045.1

Samantha Nebylitsa, S. Majumdar, D. Nolan

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引用次数: 1

Abstract

Deep-layer vertical wind shear and mid-tropospheric relative humidity (RH) are explored in and around environments of all intensifying North Atlantic tropical cyclones (TCs) between 1980–2021 using reanalysis data. Shear and RH are averaged within the standard environmental annulus of 200–800-km, along with a 100–600-km annulus, and a 0–250-km radius to represent the inner core and TC itself. Distributions of shear and RH at onset along with a time series of evolution from 48 h prior to and after onset of three different intensification rates: slight (5–10 kt 24 h−1), moderate (15–25 kt 24 h−1), and rapid (≥ 30 kt 24 h−1), are analyzed. RH is also investigated within different shear environments and in shear-relative quadrants around the storm. While low shear and high RH are found to be most favorable for rapid intensification (RI), there is still a significant probability that RI will occur within less favorable environments. RI cases decrease in 850–200-hPa shear in the 24 h leading up to RI, whereas slight intensification cases increase, which is evident in both the standard shear and a shallower layer at 48 h prior to onset. The inner-core RH for RI increases prior to onset whereas it decreases in the environments. RH analysis by shear-relative quadrants demonstrates the importance of moistening in the upshear-right quadrant before onset of RI. Results indicate the potential value of multiple annuli and shear-relative analysis for moisture and a shallower, 925–400-hPa layer for shear in RI forecasting.

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在热带气旋增强的背景下重新考虑环境风和湿度计算

利用再分析资料，探讨了1980-2021年间所有北大西洋热带气旋(tc)增强过程中及其周围环境的深层垂直风切变和对流层中层相对湿度(RH)。切变和相对湿度在200 - 800公里的标准环境环空内平均，以及100 - 600公里的环空，以及0- 250公里的半径来代表内核和TC本身。分析了三种不同增强速率(轻度(5-10 kt 24 h−1)、中度(15-25 kt 24 h−1)和快速(≥30 kt 24 h−1))发生前后48 h的剪切和相对湿度分布及其时间序列演变。在不同的切变环境和风暴周围的切变相对象限内也研究了相对相对湿度。虽然发现低切变和高相对湿度最有利于快速强化(RI)，但在不太有利的环境中发生RI的可能性仍然很大。在发生前24小时850 - 200 hpa切变中，RI病例减少，而轻度强化病例增加，这在发病前48小时的标准切变和较浅层中都很明显。RI的内核RH在发病前升高，而在环境中降低。剪切相对象限的RH分析表明，在RI发生之前，上切变右象限的润湿非常重要。结果表明，多环空和剪切相对分析对湿度和较浅的925 - 400 hpa层的剪切在RI预报中具有潜在价值。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Weather and Forecasting 地学-气象与大气科学

CiteScore

5.20

自引率

17.20%

发文量

131

审稿时长

6-12 weeks

期刊介绍： Weather and Forecasting (WAF) (ISSN: 0882-8156; eISSN: 1520-0434) publishes research that is relevant to operational forecasting. This includes papers on significant weather events, forecasting techniques, forecast verification, model parameterizations, data assimilation, model ensembles, statistical postprocessing techniques, the transfer of research results to the forecasting community, and the societal use and value of forecasts. The scope of WAF includes research relevant to forecast lead times ranging from short-term “nowcasts” through seasonal time scales out to approximately two years.