Loss of water from Venus. I. Hydrodynamic escape of hydrogen
Abstract
A one-dimensional photochemical-dynamic model is used to study hydrodynamic loss of hydrogen from a primitive, water-rich atmosphere on Venus. The escape flux is calculated as a function of the H 2O mixing ratio at the atmospheric cold trap. The cold-trap mixing ratio is then related in an approximate fashion to the H 2O concentration in the lower atmosphere. Hydrodynamic escape should have been the dominant loss process for hydrogen when the H 2O mass mixing ratio in the lower atmosphere exceeded ∼0.1. The escape rate would have depended upon the magnitude of the solar ultraviolet flux and the atmospheric euv heating efficiency and, to a lesser extent, on the O 2 content of the atmosphere. The time required for Venus to have lost the bulk of a terrestrial ocean of water is on the order of a billion years. Deutrium would have been swept away along with hydrogen if the escape rate was high enough, but some D/H enrichment should have occurred as the escape rate slowed down.
- Publication:
-
Icarus
- Pub Date:
- March 1983
- DOI:
- 10.1016/0019-1035(83)90212-9
- Bibcode:
- 1983Icar...53..479K
- Keywords:
-
- Astronomical Models;
- Atmospheric Moisture;
- Hydrodynamic Equations;
- Hydrogen;
- Photochemical Reactions;
- Venus Atmosphere;
- Deuterium;
- Escape Velocity;
- Planetary Temperature;
- Planetology;
- Radiant Heating;
- Solar Radiation;
- Ultraviolet Radiation;
- Water Vapor;
- VENUS;
- WATER;
- HYDRODYNAMICS;
- ESCAPE;
- HYDROGEN;
- PHOTOCHEMISTRY;
- MODELS;
- ATMOSPHERE;
- FLUX;
- CALCULATIONS;
- MIXING;
- CONCENTRATION;
- SOLAR RADIATION;
- ULTRAVIOLET;
- WAVELENGTHS;
- HEATING;
- DEUTERIUM