Vertical distribution features of atmospheric water vapor in the Mediterranean, Red Sea, and Indian Ocean

Measurements of total precipitable water w and of water vapor scale height H were obtained from both sun photometer measurements and soundings taken in the Mediterranean, Red Sea, and Indian Ocean during the scientific cruise of the vessel Salernum (January and February 1979). Scale height H was found to assume average values of 1.93 km for the Mediterranean leg of the cruise, 2.33 km for the Indian Ocean, and 2.45 km for the Red Sea and Somalian Coast. Moreover, average vertical distribution curves of air temperature, dew point, and absolute humidity were determined from the soundings taken in an equatorial area of the Indian Ocean. This atmospheric water vapor model gives a value of w = 5.12 g cm −2 , while the tropical model proposed by McClatchey et al. (1972) gives w = 4.20 g cm −2 . In fact, absolute humidity was found to assume appreciably higher values than those in the tropical model from sea level to about 14 km altitude and considerably smaller values throughout the tropopause region. The measurements also show that the present evaluations of scale height H can be conveniently used to represent the absolute humidity vertical profiles in tropical oceanic areas.