Stratospheric Aerosols in Jupiter's Atmosphere

Research by students from LaGuardia CC and Medgar Evers College
GISS scientist: Barbara Carlson

Summary of Previous Work

The purpose of this investigation is to examine aerosols in Jupiter's high-altitude stratospheric layer. Both spacecraft and ground-based data indicate that clouds and aerosols are present in Jupiter's atmosphere. Theoretical calculations (computer simulations), performed assuming the spacecraft retrieved thermal structure and a sun-like composition, indicate that three cloud layers should be present in the Jovian troposphere, but do not provide any constraints on the possible composition of the stratospheric aerosols.

Despite the widespread evidence of these aerosols in the Jovian atmosphere, their chemical composition and spatial distribution remain largely unknown. This team used a combination of spacecraft and ground-based measurements to examine the entire spectrum from ultra-violet through the thermal infrared, in order to investigate the physical properties and spatial distribution of the aerosols. In particular, the study focused on determining whether or not aerosols in the polar regions are the same as those found above the Great Red Spot.

Our investigation of the North Polar Region has revealed the presence of a region of enhanced thermal emission, a hot spot. Our investigation of the Jovian Great Red Spot has revealed that the temperature and cloud structure within the Red Spot in inhomogeneous, i.e., spatially variable. In addition, the collision of the Shoemaker-Levy Comet with Jupiter during July 1994 made this investigation particularly timely and relevant to this unprecedented astronomical event.

Summer 1995 Objectives

Learn more about the nature and distribution of stratospheric aerosols on Jupiter, focusing on the North Polar Region and the Great Red Spot. By focusing on two regions with enhanced aerosol amounts, we hope to learn more about the aerosols.

Methods: During the summer, we will examine the spatial structure of the North Polar Region as revealed in brightness temperature maps. We will seek to quantify the differences apparent in the brightness temperature maps by separating temperature and abundance effects. Since these results have not been previously reported, we will be preparing a journal article for submission to Icarus. To examine the time-dependent changes and a possible link to the ultra-violet auroral features, we will be adding the Voyager II data to our investigation. This will extend the time-line for our investigation.

Methods: Since our investigation revealed that the temperature and cloud structure within the Red Spot is spatially variable and this has not been previously noted at the infrared wavelengths, we will continue this investigation with the goal of performing some basic cloud and temperature structure retrievals. Our ability to investigate the stratospheric aerosols above the Great Red Spot has been hampered by our inability to isolate and enhance the stratospheric signatures in the IRIS data due to the lack of emission angle coverage in the Voyager I data. Thus, we will be adding the Voyager II data to this investigation in the hope of improving the emission angle coverage. The addition of the Voyager II data will also allow us to investigate temporal changes in the Red Spot.

Methods: A new and related research area in this investigation is to use Hubble Space Telescope images to learn more about the dynamics of the Jovian atmosphere. Our goals this summer include: (1) learning how to electronically preview and retrieve images from the HST archive; (2) surveying images for trackable features. In the process, we will also be learning how to manipulate and analyze images using the IDL programming language. Should trackable features be found, we will then navigate the images to determine the longitudinal driftrates for the cloud features. Analyses at several different wavelengths should allow us to examine the height (altitude) dependence of these motions.