The modeling and analysis research activities
at JPL consist of the development of computer programs that simulate:
• the hundreds of chemical reactions that affect atmospheric ozone
• the transport of ozone and other gases by atmospheric winds
• the thermodynamic changes that occur when air cools below the threshold for
formation of polar stratospheric clouds.
The results from these computer simulations are used to guide
the interpretation of field observations in the context of the latest laboratory
kinetic and spectroscopic parameters. Typically, the computer codes are
written in a programming language called FORTRAN and
run on Unix
workstations. A variety of graphically based programming languages are
used to display maps of meteorological data and field. observations.
Tools of the Trade: A Modeler and his Workstation
The research activities in this area are individual efforts
led by:
Mark Allen JPL/Caltech Multi-dimensional Model Lucien Froidevaux Studies of Tropospheric Ozone Michael Gunson Upper Tropospheric Trace Gases Gloria Manney Polar Vortex Evolution Ross Salawitch Photochemistry of Earth's Ozone Layer Michelle Santee Polar Stratospheric Clouds and Denitrification
Among the data sets used in these studies are satellite observations from MLS and other instruments aboard the Upper Atmospheric Research Satellite, shuttle-borne observations from ATMOS and balloon-borne observations from MkIV, and aircraft data from a number of ER-2, DC-8, and WB-57 aircraft missions. Many of the modeling efforts in recent years have been focused on understanding the details of how polar stratospheric clouds and man-made chlorine affect ozone depletion. It is well established that reactions on the surface of polar stratospheric clouds (PSCs) initiate the depletion of ozone at high latitude during winter. Our activities have used model simulations to:
• isolate the changes in ozone due to both chemistry and
transport for individual years in the Arctic and Antarctic
• determine the phase (e.g., solid or liquid) and precise composition of PSCs
based on the thermodynamic effects of these clouds on residual gas phase nitric
acid and water vapor
• understand the details of how nitric acid is permanently removed from the
polar stratosphere by sedimentation of these clouds
• assess the quantitative consistency between observed chemical loss of ozone
for individual winters and the "expected" loss based on observed
concentrations of ClO.
Other studies have played a key role in better quantifying
how ozone is affected by sulfate aerosols under conditions of both quiescent
background (e.g., non-volcanic) loadings and greatly enhanced (e.g., a factor of
30 above background) loadings that resulted following the volcanic eruption of
Mt. Pinatubo in June, 1991.
Ultimately, all of these studies are directed towards gaining
a more accurate predictive capability for future changes in stratospheric ozone.
Several of the new investigations are focused on determining
the global distribution of tropospheric ozone and gaining insight into how
space-borne observations of trace gases can be used to quantify the effect of
human activities on tropospheric ozone.
[Back to the Atmospheric Chemistry Homepage]
Author: Ross J. Salawitch
Page Design: Aaron B. Milam