Ronald A. Schorn

Mars: Detection of Atmospheric Water Vapor during the Southern Hemisphere Spring and Summer Season

Water vapor was found to reappear in the atmosphere of Mars during its southern hemisphere spring and summer season, with a maximum vertical column abundance of 45 to 50 microns of precipitable water averaged over the entire planet. Although the spring-summer seasons for each hemisphere are generally symmetrical with respect to the appearance of water vapor, the data suggest that water vapor may appear later in the season and in slightly larger amounts during the southern hemisphere spring-summer.

High-dispersion spectroscopic studies of Mars. III.: Preliminary results of 1968–1969 water-vapor studies

Abstract Recent high-resolution spectra of Mars have confirmed the existence of water vapor in the atmosphere of that planet. New laboratory measurements and improved temperature corrections have resulted in more accurate abundances than previously. In February and March of 1969, there was a mean vertical water content of 26 ± 5 precipitable microns in the northern hemisphere at a temperature of 225°K. For the southern hemisphere the amount was less than 1 3 of that in the north. Observations from November of 1968 through April of 1969 give similar results. By August and September of 1969, there was less than 5 microns everywhere on the planet. Our abundance and temperature estimates leadto a surprisingly high relative humidity (over 50%), and we feel that the possibility of small amounts of liquid water on the planet cannot be dismissed out of hand.

High-dispersion spectroscopic studies of Venus: II. The water vapor variations

We have carried out an extensive series of spectroscopic observations of Venus in the 8300-a H2O band during 1967. From April through June our results are negative, giving upper limits of 16 and 32 μ of precipitable H2O in a vertical column “above the clouds” of Venus. This agrees with the simultaneous results of Owen at 8300-A and Kuiper at 1.4 and 1.9 μ. In November and December our results were positive, and gave H2O abundances of 30–40 μ. At the same time, Kuiper also obtained a positive result from the 1.9 and 2.7 μ bands, although his abundance was much lower—only few microns. The Cytherean H2O lines appeared to be substantially stronger near the equator of Venus than at the poles.

High dispersion spectroscopic observations of Venus III. The carbon dioxide band at 7820 Å

Carbon dioxide band in Venus spectrum by dispersion analysis, deriving rotational temperature

High Dispersion Spectroscopic Observation of Venus. IV: The Weak Carbon Dioxide Band at 7883 A

The average rotational temperature of the Cytherean atmosphere above the cloud tops was found to be T(rot) = 244 +/- 10 K based on twelve plates of the 7883-A CO(2) band. If the temperatures found from the 7820-A band on the same plate are averaged with the temperatures found from the 7883-A band, we obtaina temperature of T(rot) = 245 +/- 6 K. The observations of Venus were made between April and December of 1967. Laboratory measurements of the 7883-A band are lacking, but we infer that the band is half as strong as the 7820-A band.

High-dispersion spectroscopic Studies of Venus: I. The carbon dioxide bands near 1 micron

Abstract Spectrograms of the 1-micron carbon dioxide bands on Venus at a dispersion of 5.4 A/mm were obtained on January 24, 1965, March 5, 1966, and March 9, 1966. All exposures were made with an 80-cm focal length (“B”) camera of the newly improved coude spectrograph of the Struve reflector. On the basis of our measured equivalent widths, we derived rotational temperatures of 200–250°K. This is somewhat lower than the rotational temperature found by Chamberlain and Kuiper, but about the same as the radiometric temprature obtained by Sinton and Strong. We find little variation of temperature with phase. As a check on our method of analysis we applied it to the laboratory carbon dioxide spectra of Burch et al. (1965), and found that our ability to measure rotational temperatures was more accurate than our ability to measure the absolute value of the equivalent width of an individual rotational line. All three 1-micron bands are found to lie on the same curve of growth and to follow the square-root law of absorption, as suggested by Chamberlain and Kuiper. Comparison with Spinrads data indicates a noticeable change in the scattering coefficient between 7820 A and 10 500 A. The bands show the same general phase variation as that found by Chamberlain and Kuiper but with substantially more scatter, much as Spinrad found in the case of the 7820 A band. Using a simple reflecting layer model of the Venus atmosphere, we derived an upper limit to the carbon dioxide abundance of about 1.5 km-atm. This amount is, curiously, about the same as that derived by Kuiper and Spinrad from the weaker 8689 A and 7820 A carbon dioxide bands. The high dispersion of our spectra has enabled us to begin a quantitative analysis of the (20°3–04°3)II hot band of carbon dioxide. The results agree with those obtained from the other three bands, but more observations are needed. We are now in a position to combine our results with a more realistic model of the Venus atmosphere, developed by McClatchey, in order to obtain estimates of the Venus atmospheres, developed by McClatchey, in order to obtain esimates of the carbon dioxide mixing ratio.

Comments on 'The Venus spectrum - New evidence for ice'

Abstract In a recent article in Icarus , Plummer has attempted to show that high-altitude infrared spectra obtained by Kuipers group exhibit evidence for ice-crystal clouds on Venus. He also asserts that these data are consistent with ground based spectroscopic work which indicates ∼ 100 ppt μ of water vapor “above the clouds” of Venus. Such an interpretation of the high-altitude spectra is not required by the data, and, in fact, raises more problems than it answers. The bulk of ground-based observations indicate an H 2 O abundance much less than 100 ppt μ. We come to no conclusions about the composition of the clouds of Venus; we merely point out that the airborne and ground-based spectra offer no convincing evidence for an ice-cloud composition.

Mercury: observations of the 3.4-millimeter radio emission.

Observations of the 3.4-millimeter radio emission from Mercury during 1965 and 1966 yielded the following relationship between average brightness temperature TB of the disk and the planetocentric phase angle i: TB = 277 (� 12) + 97 (� 17) cos [i + 29 deg (� 10 deg)] �K The errors are statistical standard; the phase shift corresponds to a phase lag—that is, the maximum and minimum of insolation lag the maximum and minimum of planetary radiation.