Spatiotemporal Changes of Reference Evapotranspiration in Mongolia during 1980–2006

The temporal trend and spatial distribution of reference evapotranspiration was investigated across Madagascar for the period of 1980-2010. Air temperature, relative humidity, solar radiation, and wind speed were collected from 22 weather stations across the country and were used to estimate daily reference evapotranspiration (ET 0) by the Penman-Monteith equation. Monthly average daily ET 0 and the total annual ET 0 were estimated. The Mann-Kendall test was used for the temporal trend analysis in monthly average daily ET 0 and the total annual ET 0 and the Sen's method was used to estimate the rate of change in ET 0 during the study period. The spline interpolation method was used for spatial interpolation of the variation in annual and monthly average ET 0. The results showed southwest-north East trend in ET 0. Reference evapotranspiration was higher at the western semiarid region than the humid eastern region. ET 0 peaked during the period of September-October. Annual total ET 0 varied from 1,081 mm in Andapa at northeast to 2,239 mm in Antsohihy at northwestern coastal region. Overall, there was an increasing trend in annual total ET 0 ; however, the upward trend was significant only at 7 out of 22 weather station sites while monthly ET 0 did not show consistent trends. This is one of the first comprehensive studies that investigate spatial and temporal dynamics of ET 0 in Madagascar, which can aid in developing appropriate adaptation strategies to improve crop water use and evaporative losses estimates for maintaining or increasing food production while enhancing water use efficiency in the western semiarid regions of Madagascar.

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Section: Temporal Trends Of Annual and Monthly Reference Evapotranspisupporting

confidence: 89%

Spatial and temporal trend in monthly and annual reference evapotranspiration in Madagascar for the 1980-2010 period

Djaman

Ndiaye

Koudahe

et al. 2018

IJH

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“…In Mongolia, ET 0 is influenced by the ocean, land cover, and topography. 42 In the semiarid region of northeastern China, the peak daily evapotranspiration occurred in August for the degraded grassland and cropland land surface China 43 The results of this study are in agreement with those reported by Davis 44 who observed an increase in evapotranspiration across southern Africa, including Madagascar. N, Number of years; Z, Mann-Kendall test statistic; f(year) = Q*(year-firstDataYear) + B n.s, Non-significant, +, Significant at 5%; *, Significant at 1%; **, Significant at 0.1%; ***, Significant at 0.01% Table 3 Sen's slope estimates (mm/day) and its significance for the temporal trend in monthly ET 0 across Madagascar The ET 0 patterns observed might be influenced by the topography and trade wind circulations as it significantly impacted rainfall and temperature patterns in the country.…”

Section: Temporal Trends Of Annual and Monthly Reference Evapotranspisupporting

confidence: 90%

supporting

confidence: 90%

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2018

IJH

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IntroductionReference evapotranspiration (ET 0 ) is one the most important parameters in agricultural, hydrological, and environmental studies. Despite the availability of numerous estimation methods, the Penman Monteith reference evapotranspiration method is the most accurate and being adopted worldwide and is recommended as a standardized method for ET 0 estimation under different climatic conditions. 1-2Hourly, daily, seasonal, and annual ET 0 are used for water resources planning, irrigation scheduling, rainfed agriculture, and the wetlands management. Evapotranspiration constitutes the main source of water losses at field, watershed and basin level as it is defined as the sum of the water loss by evaporation from various surfaces and transpiration from plant leaves. With the rising air temperatures on a global scale, an increase in ET 0 is expected as revealed by number of studies. Increasing trend in annual ET 0 was reported at 70% of examined weather stations in Iran with slopes varying from 2.30 to 11.28 mm/ year.3 Similar trend in ET 0 was found in Serbia. 4 Upward trend in ET 0 was reported at the rate of 1.4 mm per year during the 1957-2008 period in the Southern Italy. 5 Significant increase in annual ET 0 was reported for the Southern Senegal for the period of 1950-2000 at the rate of 2.43,4.08,0.55 and 1.85 mm/year at Tambakounda, Kedougou, Kolda and Ziguinchor, respectively,6 In Southwest China, Feng et al. 7 found a declining trend in annual ET 0 at a rate of 0.15mm/year during the 1954-2013 period. While ET 0 is showing an increasing trend in some parts of the world, it has been reported to decline in other parts. Song et al.8 reported significant decreasing trend in annual ET 0 across the North China Plain at the rate of 1.19 mm/year for the period of . Similarly, annual and seasonal ET 0 showed significant decreasing trend in North-East India.9 Irmak et al 10 reported decrease in ET 0 with a rate of 0.3596 mm/year for the period of 1893 to 2008 in the Platte River Basin, central Nebraska-USA and they attributed this decrease to an increase in precipitation with a rate of about 0.90mm/ year that significantly reduces the available energy. Huo et al.11 also found a decreasing trend in annual ET 0 at the rate of 3 mm/year in the North West China for the period of 1955-2008 due to the increase in precipitation as reported by Irmak et al.10 Zhang et al. 12 reported that annual ET 0 significantly declined at the rate of 1.29 mm/year from 1961 to 2012 in the Yellow River Basin, China. Xu et al. 13 reported a significant decreasing trend in ET 0 mainly caused by a significant decrease in the net radiation and a significant decrease in wind speed in Changjiang (Yangtze River) watershed. Liu & Zhang 14 indicated that in the driest Northwest region of China, ET 0 decreased from 1960 to 1993 at the rate of 2.34 mm/year and increased thereafter up to 2010 at the rate of 4.80 mm/year. Xing et al. 15 reported decadal variations in the ET 0 . Gao et al. 16 reported a decreasing trend in ET 0 at 46.7% of the ...

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“…Willett et al ., ; Durre et al ., ) and wind speed (see McVicar et al ., and the references therein) means some studies report increasing AED trends (e.g. Abtew et al ., ; Tabari et al ., ; Vicente‐Serrano et al ., ; Yu et al ., ) while others report decreases AED trends (e.g. Peterson et al ., ; Roderick and Farquhar, .…”

Section: Introductionmentioning

confidence: 99%

A comparison of temporal variability of observed and model‐based pan evaporation over Uruguay (1973–2014)

Vicente‐Serrano

Bidegain²,

Tomás-Burguera

et al. 2017

Intl Journal of Climatology

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This study analyses variability and trends of atmospheric evaporative demand (AED) across Uruguay in the past four decades. Changes were assessed using pan evaporation measurements from 10 meteorological stations and compared to PenPan model calculations, which is a physically based model that employs meteorological data as input. Results demonstrate a high agreement between the observed AED and those estimated from the PenPan model. Both observations and model estimations agree on a high interannual variability in AED, though being statistically insignificant (p > 0.05) at seasonal and annual scales. Given that AED shows high sensitivity to changes in relative humidity and sunshine duration, as a surrogate of solar radiation, the lack of significant trends in the AED observations and estimations over Uruguay can be linked to the insignificant trend found for these climate variables for the period from 1973 to 2014. This is the first study that reports Pan evaporation trends for this part of the world, helping to infill gaps for mid-latitude Southern Hemisphere areas, which are poorly represented in Pan evaporation trends.

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Spatiotemporal Changes of Reference Evapotranspiration in Mongolia during 1980–2006

Cited by 9 publications

References 43 publications

Spatial and temporal trend in monthly and annual reference evapotranspiration in Madagascar for the 1980-2010 period

Spatial and temporal trend in monthly and annual reference evapotranspiration in Madagascar for the 1980-2010 period

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A comparison of temporal variability of observed and model‐based pan evaporation over Uruguay (1973–2014)

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