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Three‐dimensional structures of tropical nonmigrating tides in a high‐vertical‐resolution general circulation model
Author(s) -
Sakazaki Takatoshi,
Sato Kaoru,
Kawatani Yoshio,
Watanabe Shingo
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd022464
Subject(s) - thermosphere , mesosphere , solstice , atmospheric sciences , stratopause , atmospheric tide , diabatic , stratosphere , geology , climatology , troposphere , atmosphere (unit) , environmental science , latitude , ionosphere , geophysics , meteorology , geodesy , geography , physics , adiabatic process , thermodynamics
This paper investigates nonmigrating tides from the ground to the lower mesosphere using data from a high‐resolution general circulation model (KANTO GCM), as well as observational data from the Sounding of the Atmosphere using Broadband Emission Radiometry instrument on board the Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics satellite and from GPS radio occultation measurements obtained with the COSMIC/FORMOSAT‐3 mission. We extract nonmigrating tides using a composite as a function of universal time in physical space, without performing a zonal wave number decomposition. The KANTO GCM clearly demonstrates that tropical nonmigrating tides are regarded as gravity waves excited by diabatic heating enhanced over two major continents, specifically Africa and South America. They propagate zonally, in a direction away from their sources; that is, west and eastward propagating waves are dominant on the western and eastern sides of the continents, respectively. These characteristics are observed in two satellite data sets as well, except that the amplitudes in the KANTO GCM are larger than those in the observations. Seasonal variations of nonmigrating tides are also investigated. It is suggested that filtering owing to the stratopause semiannual oscillation, as well as diabatic heating in the troposphere, is important for the seasonal variations of nonmigrating tides in the stratosphere and the lower mesosphere.