Identification

Title

A case study of the cutoff process and latent heating effect in an upper-level cold-core low during the Mei-Yu season in East Asia

Abstract

Using observational data and model sensitivity test, the present study diagnosed the evolution of an upper-level trough over 2-7 May 1998 during the mei-yu season in East Asia, with a focus on the role of latent heating downstream from the trough on the cutoff process and the formation of the cold-core low (CCL). Compared with conceptual models based on dry dynamics, the formation process of this cutoff low (COL) was inconsistent with the model of migratory jet streak-trough interaction, but the evolution of the upper-level trough (including its narrowing and rotation of axis) and the scale of the resultant COL generally agreed with the theory of interaction between trough and mean westerly flow with anticyclonic background shear. East/southeast of the trough, active and persistent convection appeared and induced 1) divergent ageostrophic flow near the tropopause, 2) an increase in mid- to upper-level thickness due to effective heating, and 3) amplification of an upper-level ridge downstream. Through a model sensitivity test, the diabatic heating is suggested to play a key role in the formation of the current CCL as the trough moved and extended southeastward to approach the amplifying ridge. Because of the east/southeast ageostrophic flow, the trough encountered a critical layer and became distorted, and its southern segment eventually detached to form a COL. When latent heating is turned off, the model produced a trough evolution anticipated by the dry theory but without cutoff. Such a role played by the moist process downstream of the trough during cutoff in the mei-yu season has not been previously noted in the literature.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7kw5gp1

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

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geoscientificInformation

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Text

originating controlled vocabulary

title

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reference date

date type

publication

effective date

2016-01-01T00:00:00Z

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East bounding longitude

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Temporal reference

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End position

Dataset reference date

date type

publication

effective date

2012-06-01T00:00:00Z

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Copyright 2012 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.

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None

Responsible organisations

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contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

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Metadata point of contact