TY - JOUR
T1 - Relating Observations of Gradient Nonbalance at the Top of Hurricanes With Their Warm Core Structures
AU - Cohen, Yair
AU - Durden, Stephen L.
AU - Harnik, Nili
AU - Heifetz, Eyal
N1 - Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/10/28
Y1 - 2019/10/28
N2 - Recent analysis of Weather Research and Forecasting simulations shows that the flow around high-pressure regions that often develop at the top of Hurricanes (15-km altitude) violates the gradient wind balance, hence termed as “gradient nonbalance.” While observations at such high altitudes are rare, recently, NASA-HS3 and the Office of Naval Research-Tropical Cyclone Intensity campaigns deployed dropsondes from unprecedented levels around 18 km. In this work we use a wavenumber decomposition method to reproduce 2-D slices and 3-D structures from three storms from these campaigns: Edouard (2014), Joaquin (2015), and Patricia (2015). The analyzed data show that the development of high pressure at the hurricane's top leads to various degrees of gradient nonbalance. These highs are a hydrostatic reflection of the storm tilt, which offsets the warm core with respect to the near surface low and the slanted eyewall. The implications of these findings and the relations with recent reports of upper-level wind field are discussed.
AB - Recent analysis of Weather Research and Forecasting simulations shows that the flow around high-pressure regions that often develop at the top of Hurricanes (15-km altitude) violates the gradient wind balance, hence termed as “gradient nonbalance.” While observations at such high altitudes are rare, recently, NASA-HS3 and the Office of Naval Research-Tropical Cyclone Intensity campaigns deployed dropsondes from unprecedented levels around 18 km. In this work we use a wavenumber decomposition method to reproduce 2-D slices and 3-D structures from three storms from these campaigns: Edouard (2014), Joaquin (2015), and Patricia (2015). The analyzed data show that the development of high pressure at the hurricane's top leads to various degrees of gradient nonbalance. These highs are a hydrostatic reflection of the storm tilt, which offsets the warm core with respect to the near surface low and the slanted eyewall. The implications of these findings and the relations with recent reports of upper-level wind field are discussed.
KW - dropsonde observations
KW - gradient non balance
KW - hurricane intensification
KW - hurricane outflow
KW - hurricane upper level observations
KW - tropical cyclone intensity
UR - http://www.scopus.com/inward/record.url?scp=85074562754&partnerID=8YFLogxK
U2 - 10.1029/2019GL084248
DO - 10.1029/2019GL084248
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AN - SCOPUS:85074562754
SN - 0094-8276
VL - 46
SP - 11510
EP - 11519
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 20
ER -