https://scholars.lib.ntu.edu.tw/handle/123456789/606339
Title: | Evolution of the tropical response to periodic extratropical thermal forcing | Authors: | Shin Y Kang S.M Takahashi K Stuecker M.F Hwang Y.-T YEN-TING HWANG |
Keywords: | Energy transport;Hadley circulation;Teleconnections;Advection;Oceanography;Surface waters;Cloud radiative effects;Energy balance models;Extratropical climate variability;Intertropical convergence zone;Moist static energy;Sea surface temperature (SST);Transient behavior;Tropical precipitation;Tropics;air-ice interaction;climate forcing;energy flow;energy flux;extratropical environment;Hadley cell;intertropical convergence zone;sea surface temperature;teleconnection;tropical environment | Issue Date: | 2021 | Journal Volume: | 34 | Journal Issue: | 15 | Start page/Pages: | 6335-6353 | Source: | Journal of Climate | Abstract: | This study examines the temporal evolution of the extratropically forced tropical response in an idealized aquaplanet model under equinox condition. We apply a surface thermal forcing in the northern extratropics that oscillates periodically in time. It is shown that tropical precipitation is unaltered by sufficiently high-frequency extratropical forcing. This sensitivity to the extratropical forcing periodicity arises from the critical time required for sea surface temperature (SST) adjustment. Low-frequency extratropical forcing grants sufficient time for atmospheric transient eddies to diffuse moist static energy to perturb the midlatitude SSTs outside the forcing region, as demonstrated by a one-dimensional energy balance model with a fixed diffusivity. As the transient eddies weaken in the subtropics, a further equatorward advection is accomplished by the Hadley circulation. The essential role of Hadley cell advection in connecting the subtropical signal to the equatorial region is supported by an idealized thermodynamical-advective model. Associated with the SST changes in the tropics is a meridional shift of the intertropical convergence zone. Since the time needed for SST adjustment increases with increasing mixed layer depth, the critical forcing period at which the extratropical forcing can affect the tropics scales linearly with the mixed layer depth. Our results highlight the important role of decadal-and-longer extratropical climate variability in shaping the tropical climate system. We also raise the possibility that the transient behavior of a tropical response forced by extratropical variability may be strongly dependent on cloud radiative effects. ? 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses). |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-85109143262&doi=10.1175%2fJCLI-D-20-0493.1&partnerID=40&md5=ebdba206a51e0599a15a447e5c6e406d https://scholars.lib.ntu.edu.tw/handle/123456789/606339 |
ISSN: | 08948755 | DOI: | 10.1175/JCLI-D-20-0493.1 |
Appears in Collections: | 大氣科學系 |
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