 A Surface Energy Balance System (SEBS) is proposed for the estimation of atmospheric turbulent fluxes and evaporative fraction using satellite earth observation data, in combination with meteorological information at proper scales SEBS consists of: a set of tools for the determination of the land surface physical parameters, such as albedo, emissivity, temperature, vegetation coverage etc, from spectral reflectance and radiance measurements; a model for the determination of the roughness length for heat transfer; and a new formulation for the determination of the evaporative fraction on the basis of energy balance at limiting cases Four experimental data sets are used to assess the reliabilities of SEBS Based on these case studies, SEBS has proven to be capable to estimate turbulent heat fluxes and evaporative fraction at various scales with acceptable accuracy The uncertainties in the estimated heat fluxes are comparable to in-situ measurement uncertainties Keywords: Surface energy balance, turbulent heat flux, evaporation, remote sensing

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The Surface Energy Balance System (SEBS) for estimation of turbulent heat fluxes

This paper gives an overview of 20 years of research on the energy balance closure problem. It will be shown that former assumptions that measuring errors or storage terms are the reason for the unclosed energy balance do not stand up because even turbulent fluxes derived from documented methods and calibrated sensors, net radiation, and ground heat fluxes cannot close the energy balance. Instead, exchange processes on larger scales of the heterogeneous landscape have a significant influence. By including these fluxes, the energy balance can be approximately closed. Therefore, the problem is a scale problem and has important consequences to the measurement and modeling of turbulent fluxes.

The energy balance closure problem: an overview.

This is a comprehensive and richly illustrated textbook on the astrophysics of the interstellar and intergalactic medium--the gas and dust, as well as the electromagnetic radiation, cosmic rays, and magnetic and gravitational fields, present between the stars in a galaxy and also between galaxies themselves. Topics include radiative processes across the electromagnetic spectrum; radiative transfer; ionization; heating and cooling; astrochemistry; interstellar dust; fluid dynamics, including ionization fronts and shock waves; cosmic rays; distribution and evolution of the interstellar medium; and star formation. While it is assumed that the reader has a background in undergraduate-level physics, including some prior exposure to atomic and molecular physics, statistical mechanics, and electromagnetism, the first six chapters of the book include a review of the basic physics that is used in later chapters. This graduate-level textbook includes references for further reading, and serves as an invaluable resource for working astrophysicists. * Essential textbook on the physics of the interstellar and intergalactic medium * Based on a course taught by the author for more than twenty years at Princeton University * Covers radiative processes, fluid dynamics, cosmic rays, astrochemistry, interstellar dust, and more * Discusses the physical state and distribution of the ionized, atomic, and molecular phases of the interstellar medium * Reviews diagnostics using emission and absorption lines * Features color illustrations and detailed reference materials in appendices * Instructor's manual with problems and solutions (available only to teachers)

Physics of the Interstellar and Intergalactic Medium

Evaporation and surface temperature

Abundances of the elements

It is shown that the process of evaporation and diffusion of water vapor from any water surface into the body of air above it is exactly similar to that of the conduction or "diffusion" of specific heat energy from the water surface into the same body of air. Because of this similarity it is possible to represent the ratio R of the heat loss by conduction to that by evaporation by the formula R=.46Tw-Ta/Pw-PaP/760 where Ta and Pa are the original temperature and vapor pressure of the air passing over the lake, and Tw and Pw are the corresponding quantities for the layer of air in contact with the water surface. The substitution of R times the evaporation loss for the value of the conduction heat loss in the Cummings equation for evaporation makes it an exact equation for the determination of evaporation from any water surface in terms of the net radiant energy absorbed by the water and the heat stored in the water.

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The Ratio of Heat Losses by Conduction and by Evaporation from any Water Surface

http://iopscience.iop.org/article/10.1086/125951/pdf

Ira S. Bowen

Papers

The Ratio of Heat Losses by Conduction and by Evaporation from any Water Surface

Excitation by line coincidence

The Spectrum and Composition of the Gaseous Nebulae

The Image-Slicer a Device for Reducing Loss of Light at Slit of Stellar Spectrograph.

The excitation of the permitted o iii nebular lines