Editorial Type:
Article
Article Type:
Research Article

Objective Verification of Clear-Air Turbulence (CAT) Diagnostic Performance in China Using In Situ Aircraft Observation

Boyan Hu aSchool of Atmospheric Sciences, Nanjing University, Nanjing, China
bMeteorological Center, East China Regional Air Traffic Management Bureau, CAAC, Shanghai, China

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https://orcid.org/0000-0003-2772-0684
,
Jinfeng Ding cCollege of Meteorology and Oceanography, National University of Defense Technology, Nanjing, China

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Gang Liu aSchool of Atmospheric Sciences, Nanjing University, Nanjing, China

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Jianping Tang aSchool of Atmospheric Sciences, Nanjing University, Nanjing, China

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Online Publication:
24 Jun 2022
Print Publication:
01 Jul 2022
DOI:
https://doi.org/10.1175/JTECH-D-20-0181.1
Page(s):
903–914
Restricted access

Abstract

This study analyzes the spatial and temporal distribution characteristics of the in situ aircraft observations in the middle and higher troposphere in 2019. These aircraft observations are mainly distributed in China, and relatively evenly recorded between 0000 and 1500 UTC in time and 6 and 10 km in height. Based on the 3395 stronger clear-air turbulence (CAT) events and 4038 weaker CAT events selected from the observations in the study region (15°–55°N, 70°–140°E), the performances of 24 CAT diagnostics calculated from the ERA5 data are evaluated. Results show that the diagnostics connected with vertical wind shear (i.e., version 1 of the North Carolina State University index, negative Richardson number, variant 3 and variant 1 of Ellrod’s turbulence index) have the best performances. However, the performances vary greatly from season to season, and overall performances are the best in winter and worst in summer. The annual and seasonal best thresholds for these diagnostics are also listed in this study.

© 2022 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Jinfeng Ding, jfding.nju@gmail.com; Jianping Tang, jptang@nju.edu.cn

Abstract

This study analyzes the spatial and temporal distribution characteristics of the in situ aircraft observations in the middle and higher troposphere in 2019. These aircraft observations are mainly distributed in China, and relatively evenly recorded between 0000 and 1500 UTC in time and 6 and 10 km in height. Based on the 3395 stronger clear-air turbulence (CAT) events and 4038 weaker CAT events selected from the observations in the study region (15°–55°N, 70°–140°E), the performances of 24 CAT diagnostics calculated from the ERA5 data are evaluated. Results show that the diagnostics connected with vertical wind shear (i.e., version 1 of the North Carolina State University index, negative Richardson number, variant 3 and variant 1 of Ellrod’s turbulence index) have the best performances. However, the performances vary greatly from season to season, and overall performances are the best in winter and worst in summer. The annual and seasonal best thresholds for these diagnostics are also listed in this study.

© 2022 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Jinfeng Ding, jfding.nju@gmail.com; Jianping Tang, jptang@nju.edu.cn
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