In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes

Abstract Recent studies have suggested that the structure of tropical cyclones (TCs), especially the upper‐level clouds as indicated by satellite infrared brightness temperatures and precipitation, fluctuates with the diurnal cycle. The diurnal cycle of the low‐level structure, including the boundar...

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Main Authors: Jun A. Zhang, Jason P. Dunion, David S. Nolan
Format: Article
Language:English
Published: Wiley 2020-02-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2019GL086206
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author Jun A. Zhang
Jason P. Dunion
David S. Nolan
author_facet Jun A. Zhang
Jason P. Dunion
David S. Nolan
author_sort Jun A. Zhang
collection DOAJ
description Abstract Recent studies have suggested that the structure of tropical cyclones (TCs), especially the upper‐level clouds as indicated by satellite infrared brightness temperatures and precipitation, fluctuates with the diurnal cycle. The diurnal cycle of the low‐level structure, including the boundary layer, has not yet been investigated with observations. This study analyzes data from 2242 GPS dropsondes collected in mature hurricanes to investigate the diurnal variation of the mean boundary layer structure. A composite analysis is conducted to compare the kinematic and thermodynamic structure during nighttime (0–6 local time) vs in the afternoon (12–18 local time). The composites show that much stronger inflow occurs during nighttime and the moist entropy is also larger than that in the daytime. Grouping the dropsonde data into 6‐h time windows relative to the local time shows a clear diurnal signal of boundary layer inflow. The amplitude of the diurnal signal is largest at a radius of 250–500 km.
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spelling doaj-art-73cc8cbb429f4e7f9454e845f2658b9f2025-08-20T02:31:27ZengWileyGeophysical Research Letters0094-82761944-80072020-02-01473n/an/a10.1029/2019GL086206In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature HurricanesJun A. Zhang0Jason P. Dunion1David S. Nolan2Hurricane Research Division NOAA/AOML Miami FL USAHurricane Research Division NOAA/AOML Miami FL USADepartment of Atmospheric Sciences University of Miami Miami FL USAAbstract Recent studies have suggested that the structure of tropical cyclones (TCs), especially the upper‐level clouds as indicated by satellite infrared brightness temperatures and precipitation, fluctuates with the diurnal cycle. The diurnal cycle of the low‐level structure, including the boundary layer, has not yet been investigated with observations. This study analyzes data from 2242 GPS dropsondes collected in mature hurricanes to investigate the diurnal variation of the mean boundary layer structure. A composite analysis is conducted to compare the kinematic and thermodynamic structure during nighttime (0–6 local time) vs in the afternoon (12–18 local time). The composites show that much stronger inflow occurs during nighttime and the moist entropy is also larger than that in the daytime. Grouping the dropsonde data into 6‐h time windows relative to the local time shows a clear diurnal signal of boundary layer inflow. The amplitude of the diurnal signal is largest at a radius of 250–500 km.https://doi.org/10.1029/2019GL086206tropical cyclonediurnal cycleboundary layermature hurricane
spellingShingle Jun A. Zhang
Jason P. Dunion
David S. Nolan
In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
Geophysical Research Letters
tropical cyclone
diurnal cycle
boundary layer
mature hurricane
title In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
title_full In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
title_fullStr In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
title_full_unstemmed In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
title_short In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
title_sort in situ observations of the diurnal variation in the boundary layer of mature hurricanes
topic tropical cyclone
diurnal cycle
boundary layer
mature hurricane
url https://doi.org/10.1029/2019GL086206
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AT jasonpdunion insituobservationsofthediurnalvariationintheboundarylayerofmaturehurricanes
AT davidsnolan insituobservationsofthediurnalvariationintheboundarylayerofmaturehurricanes