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Diurnal variations in optical depth at Mars: Observations and interpretationsViking lander camera images of the Sun were used to compute atmospheric optical depth at two sites over a period of 1 to 1/3 martian years. The complete set of 1044 optical depth determinations is presented in graphical and tabular form. Error estimates are presented in detail. Optical depths in the morning (AM) are generally larger than in the afternoon (PM). The AM-PM differences are ascribed to condensation of water vapor into atmospheric ice aerosols at night and their evaporation in midday. A smoothed time series of these differences shows several seasonal peaks. These are simulated using a one-dimensional radiative convective model which predicts martial atmospheric temperature profiles. A calculation combining these profiles with water vapor measurements from the Mars Atmospheric Water Detector is used to predict when the diurnal variations of water condensation should occur. The model reproduces a majority of the observed peaks and shows the factors influencing the process. Diurnal variation of condensation is shown to peak when the latitude and season combine to warm the atmosphere to the optimum temperature, cool enough to condense vapor at night and warm enough to cause evaporation at midday.
Document ID
19880016036
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Colburn, D. S. (NASA Ames Research Center Moffett Field, CA, United States)
Pollack, J. B. (NASA Ames Research Center Moffett Field, CA, United States)
Haberle, R. M. (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
September 5, 2013
Publication Date
May 1, 1988
Subject Category
Lunar And Planetary Exploration
Report/Patent Number
NASA-TM-100057
A-88067
NAS 1.15:100057
Accession Number
88N25420
Funding Number(s)
PROJECT: RTOP 154-20-80-16
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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