Tropopause fold investigations: Secondary circulation, water vapor and ozone analyses

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:6831423

Sun, Jielun

Tropopause folds are investigated in three parts. In the first part, the three-dimensional secondary circulation which is responsible for forcing the tropopause fold is studied in two curved jet flows. The two curved flows result from an axisymmetric, barocline vortex sheared in two ways, horizontally and vertically. The secondary circulation in cylindrical coordinates are derived under both the geostrophic and gradient balance assumptions. Beyond the geostrophic momentum (GM) approximation, momentum equations up to the second order of Rossby number are used. Model results indicate that the geostrophic advection of ageostrophic winds, curvature vorticities, which are ignored in the GM approximation could increase the aspect ratio of secondary circulation and make the secondary circulation narrower horizontally. The temperature advection along the jet can shift transverse secondary circulation horizontally depending on the sign of the advection, while the temperature advection across the jet determines the secondary circulation along the jet. In the second part, characteristics of tropopause folds on satellite 6.7-micron water vapor images are studied with observed data and theoretical models. The dark (dry) bands on satellite water vapor images can come from anywhere on the equatorial side of the tropopause break depending on the amount of water vapor in the upper troposphere above the fold. A simple cloud radiation model was studied and we found that the opaqueness of cloud depends on the amount of saturated water vapor and the size of the cloud particles. A layer of saturated water vapor is more transparent than a cloud layer of small cloud particles and less transparent than that of large particles. In the third part, patterns of vertically integrated total ozone near tropopause folds are studied with aircraft-observing ozone and two stratospheric ozone models.

• Research Organization: Yale Univ., New Haven, CT (United States)
• OSTI ID: 6831423
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ADVECTION
ASPECT RATIO
ATMOSPHERIC CIRCULATION
CLOUDS
EARTH ATMOSPHERE
ENVIRONMENTAL TRANSPORT
FLUID MECHANICS
FLUIDS
GASES
HYDROGEN COMPOUNDS
JETS
MASS TRANSFER
MECHANICS
OXYGEN COMPOUNDS
OZONE
SATELLITES
STRATOSPHERE
TROPOPAUSE
TROPOSPHERE
VAPORS
VORTICES
WATER
WATER VAPOR