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Dynamic effect of last glacial maximum ice sheet topography on the east asian summer monsoon

Gao, Yu ; Liu, Zhengyu and Lu, Zhengyao LU (2020) In Journal of Climate 33(16). p.6929-6944
Abstract

The effect of ice sheet topography on the East Asian summer monsoon (EASM) during the Last Glacial Maximum is studied using CCSM3 in a hierarchy of model configurations. It is found that receding ice sheets result in a weakened EASM, with the reduced ice sheet thickness playing a major role. The lower ice sheet topography weakens the EASM through shifting the position of the midlatitude jet, and through altering Northern Hemisphere stationary waves. In the jet shifting mechanism, the lowering of ice sheets shifts the westerly jet northward and decreases the westerly jet over the subtropics in summer, which reduces the advection of dry enthalpy and in turn precipitation over the EASM region. In the stationary wave mechanism, the lowering... (More)

The effect of ice sheet topography on the East Asian summer monsoon (EASM) during the Last Glacial Maximum is studied using CCSM3 in a hierarchy of model configurations. It is found that receding ice sheets result in a weakened EASM, with the reduced ice sheet thickness playing a major role. The lower ice sheet topography weakens the EASM through shifting the position of the midlatitude jet, and through altering Northern Hemisphere stationary waves. In the jet shifting mechanism, the lowering of ice sheets shifts the westerly jet northward and decreases the westerly jet over the subtropics in summer, which reduces the advection of dry enthalpy and in turn precipitation over the EASM region. In the stationary wave mechanism, the lowering of ice sheets induces an anomalous stationary wave train along the westerly waveguide that propagates into the EASM region, generating an equivalent-barotropic low response; this leads to reduced lower-tropospheric southerlies, which in turn reduces the dry enthalpy advection into East Asia, and hence the EASM precipitation.

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author
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publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Climate
volume
33
issue
16
pages
16 pages
publisher
American Meteorological Society
external identifiers
  • scopus:85090038571
ISSN
0894-8755
DOI
10.1175/JCLI-D-19-0562.1
language
English
LU publication?
yes
id
4b1edf3f-340e-43cd-813f-b2b6ce9404d4
date added to LUP
2020-09-25 15:08:07
date last changed
2022-04-19 00:55:13
@article{4b1edf3f-340e-43cd-813f-b2b6ce9404d4,
  abstract     = {{<p>The effect of ice sheet topography on the East Asian summer monsoon (EASM) during the Last Glacial Maximum is studied using CCSM3 in a hierarchy of model configurations. It is found that receding ice sheets result in a weakened EASM, with the reduced ice sheet thickness playing a major role. The lower ice sheet topography weakens the EASM through shifting the position of the midlatitude jet, and through altering Northern Hemisphere stationary waves. In the jet shifting mechanism, the lowering of ice sheets shifts the westerly jet northward and decreases the westerly jet over the subtropics in summer, which reduces the advection of dry enthalpy and in turn precipitation over the EASM region. In the stationary wave mechanism, the lowering of ice sheets induces an anomalous stationary wave train along the westerly waveguide that propagates into the EASM region, generating an equivalent-barotropic low response; this leads to reduced lower-tropospheric southerlies, which in turn reduces the dry enthalpy advection into East Asia, and hence the EASM precipitation.</p>}},
  author       = {{Gao, Yu and Liu, Zhengyu and Lu, Zhengyao}},
  issn         = {{0894-8755}},
  language     = {{eng}},
  number       = {{16}},
  pages        = {{6929--6944}},
  publisher    = {{American Meteorological Society}},
  series       = {{Journal of Climate}},
  title        = {{Dynamic effect of last glacial maximum ice sheet topography on the east asian summer monsoon}},
  url          = {{http://dx.doi.org/10.1175/JCLI-D-19-0562.1}},
  doi          = {{10.1175/JCLI-D-19-0562.1}},
  volume       = {{33}},
  year         = {{2020}},
}