Quick Look: Vertical profiles of H2O, H2SO4, and sulfuric acid concentration at 45–75 km on Venus

An improved model for vertical profiles of water and sulfuric acid vapors as well as sulfuric acid concentrations in the Venus clouds is presented.

From the April 2015 edition of Icarus:

Title:

Vertical profiles of H₂O, H₂SO₄, and sulfuric acid concentration at 45–75 km on Venus

Abstract:

A method developed by Krasnopolsky and Pollack (Krasnopolsky, V.A., Pollack, J.B. [1994]. Icarus 109, 58–78) to model vertical profiles of H₂O and H₂SO₄ vapors and sulfuric acid concentration in the Venus cloud layer has been updated with improved thermodynamic parameters for H₂O and H₂SO₄ and reduced photochemical production of sulfuric acid. The model is applied to the global-mean conditions and those at the low latitudes and at 60°. Variations in eddy diffusion near the lower cloud boundary are used to simulate variability in the cloud properties and abundances of H₂O and H₂SO₄ . The best version of the model for the global-mean condition results in a lower cloud boundary (LCB) at 47.5 km, H₂SO₄ peak abundance of 7.5 ppm at the LCB, and H₂Omixing ratios of 7 ppm at 62 km and 3.5 ppm above 67 km. The model for low latitudes gives LCB at 48.5 km, the H₂SO₄ peak of 5 ppm, H₂O of 8.5 ppm at 62 km and 3 ppm above 67 km. The model for 60° shows LCB at 46 km, the H₂SO₄ peak of 8.5 ppm, H₂O of 9 ppm at 62 km and 4.5 ppm above 67 km. The calculated variability is induced by the proper changes in the production of sulfuric acid (by factors of 1.2 and 0.7 for the low latitudes and 60°, respectively) and reduction of eddy diffusion near 45 km relative to the value at 54 km by factors of 1.1, 3, and 4.5 for the low and middle (global-mean) latitudes and 60°, respectively. Concentration of sulfuric acid at the low and middle latitudes varies from ∼98% near 50 km to ∼80% at 60 km and then is almost constant at 79% at 70 km. Concentration at 60° is 98% at 50 km, 73% at 63 km, and 81% at 70 km. There is a reasonable agreement between the model results and observations except for the sulfuric acid concentration in the lower clouds. Variations of eddy diffusion in the lower cloud layer simulate variations in atmospheric dynamics and may induce strong variations in water vapor near the cloud tops. Variations in temperature may affect abundances of the H₂O and H₂SO₄vapors as well.

Full Citation:

Krasnopolsky, V. (2015). Vertical profiles of H₂O, H₂SO₄, and sulfuric acid concentration at 45–75km on Venus Icarus, 252, 327-333 DOI: 10.1016/j.icarus.2015.01.024