干旱区生态环境知识资源中心(Arid): Correcting Hargreaves-Samani formula using geographical coordinates and rainfall over different timescales

Arid

DOI	10.1002/hyp.14790
	Correcting Hargreaves-Samani formula using geographical coordinates and rainfall over different timescales
	Elagib, Nadir Ahmed; Musa, Ammar Ahmed
通讯作者	Elagib, NA
来源期刊	HYDROLOGICAL PROCESSES
ISSN	0885-6087
EISSN	1099-1085
出版年	2023
卷号	37 期号:1
英文摘要	The United Nations Food and Agricultural Organization (FAO) approved the Hargreaves-Samani formula (HAR-85) as an alternative to the standard Penman-Monteith method (FAO-PM) for estimating grass reference evapotranspiration (ETo). With much less data demand, HAR-85 is unequivocally useful where meteorological variables are often scarce, incomplete or unavailable. Herein, we evaluate HAR-85 against FAO-PM across 2.505 million km(2), representing Sudan and South Sudan and encompassing wide hydroclimate domains including the Nile River. We further propose simple year-round and seasonal adjustment models to correcting HAR-85 across the entire study area. The models express HAR-85's error in multiple linear regressions in terms of latitude, longitude, altitude and/or monthly rainfall. Varying data periods, including odd, even and all years, are used in the evaluation and the adjustment models development and validation processes to investigate the influence of changing data period. A suit of eight performance indicators shows dependency of the original bias of HAR-85 on the geographical location, monthly rainfall amount, season of the year and data period. All error indicators amplify southward from the hyper-arid region to the dry sub-humid zone. For example, the mean bias error (MBE) ranges from -0.51 to 1.29 mm/day, respectively. Study area-wide, HAR-85 least represents FAO-PM during the hottest month and the transitional month (between the wet and dry-cool seasons) with MBE of 0.65 and 0.70 mm/day, respectively. Conversely, it represents FAO-PM the most in the wettest month, with smallest MBE of 0.32 mm/day. Beholding this spatiotemporal trait, the final yearly and seasonal adjustment models developed herein enormously moderate the predominant overestimation of the original HAR-85. The former model explains 46.7% of the error variance whereas 36.9% to 62.3% of the variation in the error is explainable by the latter models. These adjustment models narrow the monthly MBE among the stations from -0.71-2.17 to -0.80-1.20 and -0.65-0.99 mm/day, respectively. Without undermining the accuracy, the year-round adjustment model can still be feasibly recommended for general use across the study area.
英文关键词	arid climates evaluation FAO Penman-Monteith method grass reference evapotranspiration Hargreaves-Samani method sub-humid climates Sudan validation
类型	Article
语种	英语
开放获取类型	hybrid
收录类别	SCI-E
WOS记录号	WOS:000909568600001
WOS关键词	REFERENCE EVAPOTRANSPIRATION EQUATIONS ; CROP EVAPOTRANSPIRATION ; SOLAR-RADIATION ; CALIBRATION ; DROUGHT ; HYDROLOGY ; TRENDS ; INDEX ; WATER
WOS类目	Water Resources
WOS研究方向	Water Resources
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/396867
推荐引用方式 GB/T 7714	Elagib, Nadir Ahmed,Musa, Ammar Ahmed. Correcting Hargreaves-Samani formula using geographical coordinates and rainfall over different timescales[J],2023,37(1).
APA	Elagib, Nadir Ahmed,&Musa, Ammar Ahmed.(2023).Correcting Hargreaves-Samani formula using geographical coordinates and rainfall over different timescales.HYDROLOGICAL PROCESSES,37(1).
MLA	Elagib, Nadir Ahmed,et al."Correcting Hargreaves-Samani formula using geographical coordinates and rainfall over different timescales".HYDROLOGICAL PROCESSES 37.1(2023).