Pathfinder Model Images

Modeling Pathfinder images will help us learn more about the dust and clouds in the Martian atmosphere, up close and personal. Here is a web site with pictures from Pathfinder. And here is a model image:

This shows the an all-sky of mars viewed from the surface. From left to right, the view spans the entire azimuth; that is, 360 degrees; from top to bottom, the view ranges from -90 degrees (looking down) to +90 (looking straight up). The sun sits 20 degrees above the horizon. We use a peeling-off algorithm that calculates how much radiation will go in a certain direction (to the pathfinder position) at each interaction in the atmosphere (Yusef-Zadeh, Morris, & White 1984, ApJ, 278, 186). This image combines 3 models at three different wavelengths (blue, green, and red) to make a 'true-color' image. The model parameters are given in the table below:

Scattering parameters used in this simulation

wavelength (nm)	410 (blue)	502 (green)	673 (red)
dust albedo	0.64	0.75	0.93
surface albedo	0.04	0.06	0.25
atmosphere optical depth (normal to surface)	0.376	0.4	0.42
dust average cosine of scattering angle = g	0.78	0.73	0.68
relative incident solar flux	160	185	152

These are average values determined from previous models of the Martian atmosphere.

Using our code, we will investigate the unexpectly long twilight phenomenon measured by Pathfinder (Smith et al. 1997, Science 278, p. 1758-1765). We will vary the scattering properties of the dust, within reason, to determine if we can reproduce the brightness via dust scattering at high levels in the atmosphere

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