Influence of Radiation on Evaporation Rates: A Numerical Analysis

Abstract

We present a fully coupled soil-atmosphere model that includes radiation in the energy balance of the coupling conditions between the two domains. The model is able to describe evaporation processes under the influence of turbulence, surface roughness, and soil heterogeneities and focuses specifically on the influence of radiation on the mass and energy transport across the soil-atmosphere interface. It is shown that evaporation rates are clearly dominated by the diurnal cycle of solar irradiance. During Stage-I evaporation maximum temperatures are regulated due to evaporative cooling, but after a transition into Stage-II evaporation, temperatures rise tremendously. We compare two different soil types, a coarser, sandy soil and a finer, silty soil, and analyze evaporation rates, surface temperatures, and net radiation for three different wind conditions. The influence of surface undulations on radiation and evaporation is analyzed and shows that radiation can lead to different local drying patterns in the hills and the valleys of the porous medium, depending on the height of the undulations and on the direction of the Sun. At last a comparison of lysimeter measurement data to the numerical examples shows a good match for measured and calculated radiation values but evaporation rates are still overestimated in the model. Possible reasons for the discrepancy between measurement and model data are analyzed and are found to be uncertainties about the parameters close to the interface, which are decisive for determining evaporation rates. Several models are available that are able to describe evaporation with different levels of complexity, especially regarding simplifications made for the coupling conditions between the soil and the atmosphere.

Introducing affordable and accessible physical covers to reduce evaporation from agricultural water reservoirs and pools (field study, statistics, and intelligent methods)

“…The reason is the variation of climatic conditions at the beginning and end of the evaporation data collection period. Figure 9 is drawn like Bontempo Scavo et al (2021) and Heck et al (2020). As observed, the average height of the station evaporation (class A pan) and the observational evaporation height (Colorado pan) are close to each other.…”

Do sediments of ephemeral and perennial streams show different impacts on water quality when subjected to the same drying conditions?

“…Average evaporation in field was 1500 mm/year (4.1 mm/day) and this was closely paralleled with a 5 mm/day evaporation during the experiment. These rates of evaporation are the pan evaporation rate under direct sunlight, therefore the evaporation of the mesocosms which had canopy shade was observed to be significantly lower and similar to field conditions near the streams sampled (Heck et al, 2020).…”

Coupling staggered-grid and MPFA finite volume methods for free flow/porous-medium flow problems

“…Comparing the existing monolithically solved method with a partitioned model domains are solved individually [24], or to other domain decomposition models using interface mortars [5], could also provide insight to other solution methods. For expansions to the free-flow domain, turbulence models and radiation based expansions to the energy balance could be introduced to better simulate atmospheric free-flow conditions [20,9]. To expand on the discretization in the free-flow domain, unstructured and adaptive staggered finite volume methods are being developed in order to efficiently resolve more complex geometries and flow cases.…”