Vertical Water Distribution Research Articles

Vertical Distribution of Water in the Atmosphere of Venus: A Simple Thermochemical Explanation

Several lines of evidence concerning the vertical abundance profile of water in the atmosphere of Venus lead to strikingly unusual distributions (the water vapor abundance decreases sharply in the immediately vicinity of the surface) or to serious conflicts in the profiles (different infrared bands suggest water abundances that are discrepant by a factor of 2.5 to 10). These data sets can be reconciled if (i) water molecules associate with carbon dioxide and sulfur trioxide to make gaseous carbonic acid and sulfuric acid in the lower atmosphere, and (ii) the discrepant 0.94-micrometer water measurements are due to gaseous sulfuric acid, requiring it to be a somewhat stronger absorber than water vapor inthis wavelength region. A mean total water abundance of 50 +/- 20 parts per million and a near-surface free water vapor abundance of 10 +/- 4 parts per million are derived.

MICROCOMPUTER SIMULATION MODEL OF SOIL WATER EXTRACTION BY SOYBEANS

This paper describes a simple microcomputer simulation model that calculates changes in the vertical distribution of water beneath a crop from weather, plant, and soil physical data. Simulated patterns of water extraction by soybeans in western Iowa agreed well with measured patterns. The model requires only about 10K of memory, so the simulation can be adapted readily to form part of a more complex model.

Simulation of the water distribution in soil

A previous model for simulation of the vertical distribution of water in a fallow soil has been developed to include water extraction by plant roots. Results from the model agreed well with field measurements, the main differences being caused by horizontal variations in root density, hysteresis in the soil hydraulic properties and by the apparently anomalous infiltration behaviour of the field soil. The model demonstrated the simulated effects on water extraction of root hydraulic resistance, of non-polar flow in the roots, and the capacity of the plant to store water.

THE MOISTURE CONTENT OF THE TRUNKS OF MONTEREY PINE TREES

SUMMARY Investigations were carried out between 1939 and 1942 in South Australia to determine the amount and distribution of moisture within the trunks of Monterey pine trees (P. radiata Don) and to study the differences from tree to tree. Between 1946 and 1948, additional but less extensive investigations were conducted in the Australian Capital Territory. Large variations occur within each tree. The vertical distribution of water shows several distinct trends: in some trees the moisture content decreases from the base to a minimum and then increases again towards the top, in others it increases progressively up the tree, while in other trees it decreases progressively with height. The heartwood is a dry region with a moisture content of approximately 45 per cent. The moisture content of the sapwood varies throughout the tree both vertically and laterally. Big differences in moisture content occur from tree to tree. The wood of young trees is much moister than that of old trees and the moisture content o...