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Effects of diurnal variation of solar zenith angle on a tropical coupling system: A two‐dimensional coupled ocean‐cloud resolving atmosphere modeling study
Author(s) -
Gao Shouting,
Zhou Yushu
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl034340
Subject(s) - zenith , solar zenith angle , atmospheric sciences , environmental science , atmosphere (unit) , cloud albedo , diurnal temperature variation , cloud cover , meteorology , geology , physics , remote sensing , cloud computing , computer science , operating system
The effects of diurnal variation of solar zenith angle on tropical atmospheric and oceanic variability are investigated with a two‐dimensional coupled ocean‐cloud resolving atmosphere model. The experiment with a time‐invariant solar zenith angle is compared to the control experiment with a diurnally‐varied solar zenith angle. In both experiments, the model, with imposed large‐scale vertical velocity and zonal wind derived from Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE), is integrated over a 30‐day period. The control simulation shows a good agreement with the observations in terms of atmospheric temperature, specific humidity, and mixed‐layer temperature and salinity. The experiment with the time‐invariant solar zenith angle produces a colder and drier atmosphere and a colder and saltier ocean mixed layer than the experiment with the diurnally‐varied solar zenith angle does. The atmospheric temperature and precipitable water budgets and oceanic mixed‐layer temperature and salinity budgets are analyzed. Compared to the experiment with the diurnally‐varied solar zenith angle, the experiment with the time‐invariant solar zenith angle has smaller solar heating, consumes more atmospheric water vapor through more condensation, and generates smaller thermal forcing through deeper mixed layer and more saline entrainment. The results indicate the importance of the inclusion of diurnal variation of solar zenith angle in coupled model simulations to avoid atmospheric and oceanic cooling biases and atmospheric drying bias.