Jupiter’s North pole has a dark spot which was first seen by the Hubble Space Telescope in September 1997 and then in 2000 by the Cassini space craft on its way to Saturn. This research will look at Jupiter in the filters 218nm, 255nm, 336nm, 410nm, 673nm, 890nm (methane absorption filter), and 953nm. Data will be looked at from 5 to 6 locations in the dark spot. Also data at times when the spot is not present (Aug ‘99, Nov ‘97, Jun ‘96) will be looked at for comparison. Spectral transmission (brightness) plots of these points will be made. It is hoped to obtain clues as to the composition of the aerosols in the North Polar Region because we believe aerosols created the dark spot.

Aerosols are solid or liquid particles suspended in the atmosphere. They reflect and scatter light, causing some of the radiation from the sun to bounce back into space, generating a cooling effect on the atmosphere. Our goal is to evaluate the role aerosols play in earth’s climate change. Aerosols vary in size, composition, and lifetime. This makes it extremely hard to quantify their cooling effect, which is comparable in magnitude to the warming effect of greenhouse gases. Various remote sensing instruments retrieve information about aerosol properties, which include the size distribution, Aerosol Optical Thickness (AOT) also denoted by τ, and the refractive index of the aerosols. The ongoing project at LaGuardia Community College involves the use of a handheld polarimeter, a CIMEL sunphotometer, and two handheld Microtop sunphotometers to characterize the aerosols in our atmosphere. The studies that we conduct will ultimately help scientists make better computer models which make predictions about future climate change.

This project involves the use of a hand-held polarimeter, a rotating shadowband radiometer, and a CIMEL sunphotometer. By analyzing the data from all three ground instruments accurate values for the optical depth, the size, and refractive index of the aerosols can be obtained. Such information will be used by scientists to develop better computer models which make predictions about future climate change.

Conclusion:
Both the data from the LaGuardia Community College MFR and the hand-held polarimeter seem to confirm the data from the CIMEL at CCNY, since all instruments measured a tau near .30.

On July 17, as shown by the CIMEL radius plot, most of the aerosols were comprised of either two sizes: .1 (fine) or 5 (coarse) microns. Since the polarimeter cannot account for these coarse aerosols due to its being monomodal, variations existed in the data for each of the color wavelengths. This is also why an exact refractive index could not be obtained but instead approximated at a range of 1.35-1.45.

The greatest uncertainty in the forecasting of future climate is probably the role that aerosols play in the energy budget of the planet. They can either heat up or cool down the atmosphere depending on their composition. The magnitude of their forcing is somewhere between +0.5 to –0.5 Watts/sqm which is comparable to the magnitude of the warming produced by the greenhouse gases. Due to the wide range of their possible compositions, their variability of time being suspended in the atmosphere, and their wide variations in temporal and spatial characteristics, their role in the role climate remains unknown both on a local and global scale.

Satellites are currently being used to investigate aerosols properties. However their retrieval algorithms give values for the aerosol optical depth, a value related to the concentration, their size distribution, and refractive index, but ground measurements are needed for calibration and validation of these results. Sunphotometer networks are currently being used and it is found that they can accurately verify optical depths of the aerosols, but beyond that their values for size distributions and refractive index are questionable.

The Hand-Held Polarimeter Project seeks to aid in the verifications of satellite and sunphotometer parameter retrievals by offering another ground based method of obtaining the aerosol optical depth, particle size, and refractive index. The project will consider a new technique for data collection and analysis which will combine the sunphotometer and polarimeter techniques. The sunphotometer value for the optical depth will be used as an input into the polarimeter retrieval algorithm and from this the polarimeter values for refractive index and particle size will be derived. Initial results indicate this will give superior values for the refractive indices. This project seeks to investigate this technique further. The polarimeter instruments are student built at a cost of about $55. The project involves student data collection and data analysis.

Study of the Great Dark Vortex on Jupiter is meant to discover how and why the vortex forms and what factors contribute to its formation. The Great Dark Vortex, also known as the Great Dark Spot is currently under investigation for its peculiar formation and deterioration. The three dates studied are on September 1997 with the dark spot clearly visible, November 1997 with signs of the deterioration of the Great Dark Spot and its trail, and on August 1999 with no sign of the Great Dark Spot. This information is gathered using the Hubble Space Telescope.