Water Vapor Abundances over Mars North High Latitude Regions: 1996–1999

Abstract We present column abundances of water vapor in Mars' atmosphere over high north latitudes for L s 46°–146° during 1996–1997 and L s 34°–180° during 1998–1999. These abundances have been obtained by ground-based high-resolving-power spectroscopy in the very near IR (8174–8200 A) from the 1.5-m Catalina observatory near Tucson, AZ. All of the measurements have been corrected for atmospheric dust opacity, which increases the measured water vapor abundance over the “apparent measurement” by appreciable amounts at long path lengths. Dust measurements in 1998–1999 were made by near simultaneous measurements, with the same instrument, of the CO 2 absorption lines in the nearby spectral region between 8689 and 8692 A. We use a doubling and adding radiative transfer code to obtain the dust optical thickness. High northern latitude dust opacities were between 0.8 and 1.0 in this data set for 1998–1999. For the high-latitude measurements made in 1996–1997 during and following observed spring dust storm activity, the dust opacity (τ dust =0.8) was adopted. The computations account for the geometry of the observations (incoming airmass, outgoing airmass, and phase angle). Measurements show a strong increase in water vapor abundance from 8 to 76 ppt. μm with onset of spring and early summer ( L s 34°–118°) followed by an abrupt drop to less than 1 ppt. μm by summer's end.

[1]  B. Jakosky,et al.  Comparison of ground-based and Viking Orbiter measurements of Martian water vapor: Variability of the seasonal cycle , 1984 .

[2]  Jeffrey R. Barnes,et al.  General circulation model simulations of the Mars Pathfinder atmospheric structure investigation/meteorology data , 1999 .

[3]  J. W. Chamberlain.  Theory of planetary atmospheres , 1978 .

[4]  D. W. Davies.  The vertical distribution of Mars water vapor , 1979 .

[5]  M. Lemmon,et al.  Opacity of the Martian atmosphere measured by the Imager for Mars Pathfinder , 1999 .

[6]  P. James,et al.  North Polar Dust Storms in Early Spring on Mars , 1999 .

[7]  R. L. Hilliard,et al.  A CASSEGRAIN ECHELLE SPECTROGRAPH , 1991 .

[8]  D. Hunten,et al.  Martian water vapor, 1988–1995 , 1996 .

[9]  David E. Smith,et al.  The global topography of Mars and implications for surface evolution. , 1999, Science.

[10]  B. Jakosky,et al.  The Mars Water Cycle: Determining the Role of Exchange with the Regolith☆ , 1997 .

[11]  Robert M. Haberle,et al.  A coupled subsurface‐boundary layer model of water on Mars , 1993 .

[12]  David A. Paige,et al.  The seasonal cycle of carbon dioxide on Mars , 1992 .

[13]  E. Barker.  Martian atmospheric water vapor observations: 1972–1974 apparition , 1976 .

[14]  Mark T. Lemmon,et al.  Properties of dust in the Martian atmosphere from the Imager on Mars Pathfinder , 1999 .

[15]  D. W. Davies,et al.  Mars: Water vapor observations from the Viking orbiters , 1977 .

[16]  Hannu Savijärvi,et al.  Mars boundary layer modeling: Diurnal moisture cycle and soil properties at the Viking Lander 1 Site. , 1995 .

[17]  John C. Pearl,et al.  Mars Global Surveyor Thermal Emission Spectrometer (TES) observations of dust opacity during aerobraking and science phasing , 2000 .

[18]  B. Jakosky.  The role of seasonal reservoirs in the Mars water cycle: II. Coupled models of the regolith, the polar caps, and atmospheric transport , 1983 .

[19]  C. B. Farmer,et al.  The seasonal and global behavior of water vapor in the Mars atmosphere: Complete global results of the Viking Atmospheric Water Detector Experiment , 1982 .

[20]  D. W. Davies,et al.  Measurements of water vapor in Mars' Antarctic , 1981 .

[21]  F. Flasar,et al.  Diurnal behaviour of water on Mars , 1976 .

[22]  D. Hunten,et al.  Correction for Dust Opacity of Martian Atmospheric Water Vapor Abundances , 2000 .

[23]  Daniel M. Troiani,et al.  TELESCOPIC OBSERVATIONS OF MARS, 1996-1997 : RESULTS OF THE MARSWATCH PROGRAM , 1999 .

[24]  J. Bell,et al.  1995 observations of Martian dust storms using the Hubble Space Telescope , 1996 .

[25]  B. Jakosky.  The role of seasonal reservoirs in the Mars water cycle. I Seasonal exchange of water with the regolith. II - Coupled models of the regolith, the polar caps, and atmospheric transport , 1983 .

[26]  M. J. Wolff,et al.  An intercomparison of ground-based millimeter, MGS TES, and Viking atmospheric temperature measurements: Seasonal and interannual variability of temperatures and dust loading in the global Mars atmosphere , 2000 .

[27]  Stephen M. Clifford,et al.  A model for the hydrologic and climatic behavior of water on Mars , 1993 .