Surface forcing of the infrared cooling profile over the Tibetan Plateau. Part I: Influence of relative longwave radiative heating at high altitude

Journal Article · Fri May 15 04:00:00 EDT 1992 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1992)049<0805:SFOTIC>2.0.CO;2· OSTI ID:5648452

Smith, E A; Shi, L ^[1]

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1. Florida State Univ., Tallahassee, FL (United States)

The role of the Tibetan Plateau on the behavior of the surface longwave radiation budget is examined, and the behavior of the vertical profile of longwave cooling over the plateau, including its diurnal variation, is quantified. The investigation has been conducted with the aid of datasets obtained during the 1986 Tibetan Plateau Meteorological Experiment (TIPMEX-86). A medium spectral-resolution infrared radiative transfer model using a simple modification for applications in idealized complex (valley) terrain is developed for the study. This study focuses on the clear-sky case where the surface effects are most significant. The TIPMEX-86 data, obtained during the spring-summer transition into the East Asian monsoon season, are used to help validate the surface longwave radiation budget at two sites of varying elevation. It is shown that relative longwave heating extends the period of the day over which the plateau acts as a direct heat source to the atmosphere. Computational results from the infrared model help substantiate observational analyses that indicate surface longwave net radiation at the high-elevation site, on clear days, exceeds 300 W m[sup [minus]2]; this is an order of magnitude greater than typical of sea-level oceanic conditions. As a result of the unique meteorological and surface conditions, total infrared flux convergence occurs within the deep planetary boundary layer at the high-elevation site during the afternoon. An important characteristic of the daytime longwave heating process of the lower layers is how it turns off like a switch at approximately 1800 MST, transforming almost immediately to maximum cooling of the lower layers. Atmospheric longwave cooling is significantly influenced by variations in the biophysical composition of the surface and the associated thermal diurnal cycle. 50 refs., 11 figs., 3 tabs.

• OSTI ID: 5648452
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 49:10; ISSN JAHSAK; ISSN 0022-4928
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ASIA
ATMOSPHERIC CIRCULATION
COOLING
DAILY VARIATIONS
ELECTROMAGNETIC RADIATION
ENERGY BUDGETS
INFRARED RADIATION
METEOROLOGY
RADIATIONS
RADIATIVE COOLING
TEMPERATURE DEPENDENCE
TIBET
VARIATIONS