The surface energy balance algorithm for land (SEBAL) estimates land surface evapotranspiration (ET) from radiometric surface temperature (TR), but requires manual selection of calibration pixels, which can be impractical for mapping seasonal ET. Here pixel selection is automated and SEBAL implemented using global climate grids and satellite imagery. SEBAL is compared with the MOD16 algorithm, which uses remotely sensed data on vegetation condition to constrain reference ET from the Penman‐Monteith equation. The difference between the evaporative fraction (Λ, range 0–1) from SEBAL and six eddy flux correlation towers was less than 0.10 for three of six towers, and less than 0.24 for all towers. SEBAL ET was moderately sensitive to surface roughness length and implementation over regions smaller than ∼10,000 km2 provided lower error than larger regions. Pixel selection based on TR had similar errors as those based on a vegetation index. For maize, MOD16 had lower error in mean seasonal evaporative fraction (−0.02) compared to SEBAL Λ (0.23), but MOD16 significantly underestimated the evaporative fraction from rice (−0.52) and cotton fields (−0.67) compared with SEBAL (−0.09 rice, −0.09 cotton). MOD16 had the largest error over short crops in the early growing season when vegetation cover was low but land surface was wet. Temperature‐based methods like SEBAL can be automated and likely outperform vegetation‐based methods in irrigated areas, especially under conditions of low vegetation cover and high soil evaporation.

No abstract

Purpose-This paper aims to consider whether ethical persuasion can be part of public relations practice. Design/methodology/approach-The paper contends that the critical issue for practitioners is not whether they engage in persuasion, but whether they do so ethically. Accordingly, a definition of ethical persuasion is derived by examining unethical propaganda. The paper then considers what standard might be used to assess the ethics of persuasion. The notion of "the public interest"ubiquitously linked to ethical practice in public relations-is considered but found to be too elusive to guide the practice individual practitioners. Other more assessable standards are identified, as is a guiding approach to ethics. The approach to ethics adopted in this paper is rule utilitarianism. The methodology of this paper is deductive and derivative analysis, argument and synthesis, drawn from a broad body of literature. Findings-Persuasion can be ethical, and a definition of ethical persuasion is proffered. The public interest is not a standard that individual practitioners can determine, decide, know, or apply to assess the ethics of their practice. Ethical persuasion can, however, be assessed using other standards, discussed in the paper. Consequently, a set of criteria and standards to practicing ethical persuasion is developed. Research limitations/implications-The paper does not extend into a discussion of practical persuasive techniques. Therefore, an extension of this examination could consider a thorough assessment of the ethics of practical persuasive communication techniques. Practical implications-Directly relevant to the daily work of public relations practitioners, communicators, adertisers and marketers, who are interested in acting ethically. The paper provide a basis for a guide to assessing the ethics of persuasive practice. Originality/value-This paper confronts both the question of whether practitioners can use the notion of the public interest to assess the ethics of practice, and also what constitutes ethical (and unethical) persuasion, and considers how persuation can be used ethically.

No abstract

No abstract