Clustering analysis of regional reference evapotranspiration and its components based on climatic variables across northeast China, 1961–2010

2015 ◽  
Vol 7 (1) ◽  
pp. 128-141 ◽  
Author(s):  
Yuan Liu ◽  
Buchun Liu ◽  
Xiaojuan Yang ◽  
Wei Bai
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Northeast China ◽  
Reference Evapotranspiration ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Regional Distribution ◽  
Climatic Variables ◽  
Maximum Temperature ◽  
Sunshine Hours

Evapotranspiration integrates atmospheric demand and surface conditions. The Penman-Monteith equation was used to calculate annual and seasonal reference evapotranspiration (ET0) and thermodynamic and aerodynamic components (ETrad and ETaero) at 77 stations across northeast China, 1961–2010. The results were: (1) annual ETrad and ETaero had different regional distribution, annual ETrad values decreased from south to north, whereas the highest ETaero values were recorded in the eastern and western regions, the lowest in the central region; (2) seasonal ETaero distributions were similar to seasonal ET0, with a south–north longitudinal pattern, while seasonal ETrad distributions had a latitudinal east-west pattern; and (3) in the group for ET0 containing 69 sampling stations, effects of climatic variables on ET0 followed sunshine hours > relative humidity > maximum temperature > wind speed. Changes in sunshine hours had the greatest effect on ETrad, but wind speed and relative humidity were the most important variables to ETaero. The decline in sunshine duration, wind speed, or both over the study period appeared to be the major cause of reduced potential evapotranspiration in most of NEC. Wind speed had opposite effects on ETrad and ETaero, and therefore the effect of wind speed on ET0 was not significant.

scholarly journals Comparative Study of Evapotranspiration Variation and its Relationship with other Climatic Parameters in Asaba and Uyo

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Okwunna M Umego ◽  
Temitayo A Ewemoje ◽  
Oluwaseun A Ilesanmi
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Solar Radiation ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Small Variation ◽  
Climatic Variables ◽  
Maximum Temperature ◽  
Climatic Parameters ◽  
Sunshine Hours

This study was carried out to assess the variations of Reference Evapotranspiration (ETO also denoted with RET) calculated using FAO-56 Penman Monteith model of two locations Asaba and Uyo and evaluate its relationships with the variations of other climatic parameters. Meteorological data of forty one years (1975-2015) and thirty five years (1981-2015) period for Asaba and Uyo, respectively gotten from Nigeria Meteorological Agency, Abuja were used. It was observed that the variations of Evapotranspiration (ET) in both locations were in line with two seasons (rainy and dry) normally experienced in Nigeria having its highest value in March (4.8 mm/day) for Asaba and for Uyo in February (4.5 mm/day); and its lowest value in August (3.1 mm/day) for Asaba and in July (2.9 mm/day) for Uyo. ET variation when compared with other climatic variables in both locations was observed to have the same trend with maximum temperature, solar radiation and sunshine hours. It also has the same variation with minimum temperature though with slight deviation. It was observed that ET variation is inversely proportional to the variation relative humidity. Wind speed displayed relatively small variation in its trend over the study period and is not in line with the variations of ET.Keywords— Evapotranspiration, Climatic Variables, FAO Penman-Monteith Model, Variations

scholarly journals Trend and Sensitivity Analysis of Reference Evapotranspiration in the Senegal River Basin Using NASA Meteorological Data

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1957
Author(s):  
Papa Malick Ndiaye ◽  
Ansoumana Bodian ◽  
Lamine Diop ◽  
Abdoulaye Deme ◽  
Alain Dezetter ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Wind Speed ◽  
Relative Humidity ◽  
River Basin ◽  
Reference Evapotranspiration ◽  
Climatic Variables ◽  
Maximum Temperature ◽  
Senegal River ◽  
Senegal River Basin ◽  
Basin Area

Understanding evapotranspiration and its long-term trends is essential for water cycle studies, modeling and for water uses. Spatial and temporal analysis of evapotranspiration is therefore important for the management of water resources, particularly in the context of climate change. The objective of this study is to analyze the trend of reference evapotranspiration (ET0) as well as its sensitivity to climatic variables in the Senegal River basin. Mann-Kendall’s test and Sen’s slope were used to detect trends and amplitude changes in ET0 and climatic variables that most influence ET0. Results show a significant increase in annual ET0 for 32% of the watershed area over the 1984–2017 period. A significant decrease in annual ET0 is observed for less than 1% of the basin area, mainly in the Sahelian zone. On a seasonal scale, ET0 increases significantly for 32% of the basin area during the dry season and decreases significantly for 4% of the basin during the rainy season. Annual maximum, minimum temperatures and relative humidity increase significantly for 68%, 81% and 37% of the basin, respectively. However, a significant decrease in wind speed is noted in the Sahelian part of the basin. The wind speed decrease and relative humidity increase lead to the decrease in ET0 and highlight a “paradox of evaporation” in the Sahelian part of the Senegal River basin. Sensitivity analysis reveals that, in the Senegal River basin, ET0 is more sensitive to relative humidity, maximum temperature and solar radiation.

scholarly journals Potential Evapotranspiration Reduction and Its Influence on Crop Yield in the North China Plain in 1961–2014

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Wanlin Dong ◽  
Chao Li ◽  
Qi Hu ◽  
Feifei Pan ◽  
Jyoti Bhandari ◽  
...  
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Crop Yield ◽  
North China Plain ◽  
North China ◽  
Potential Evapotranspiration ◽  
The North ◽  
The North China Plain ◽  
Sunshine Hours ◽  
Humidity Index

Climate change has caused uneven changes in hydrological processes (precipitation and evapotranspiration) on a space-temporal scale, which would influence climate types, eventually impact agricultural production. Based on data from 61 meteorological stations from 1961 to 2014 in the North China Plain (NCP), the spatiotemporal characteristics of climate variables, such as humidity index, precipitation, and potential evapotranspiration (ET0), were analyzed. The sensitivity coefficients and contribution rates were applied to ET0. The NCP has experienced a semiarid to humid climate from north to south due to the significant decline of ET0 (−13.8 mm decade−1). In the study region, 71.0% of the sites showed a “pan evaporation paradox” phenomenon. Relative humidity had the most negative influence on ET0, while wind speed, sunshine hours, and air temperature had a positive effect on ET0. Wind speed and sunshine hours contributed the most to the spatiotemporal variation of ET0, followed by relative humidity and air temperature. Overall, the key climate factor impacting ET0 was wind speed decline in the NCP, particularly in Beijing and Tianjin. The crop yield in Shandong and Henan provinces was higher than that in the other regions with a higher humidity index. The lower the humidity index in Hebei province, the lower the crop yield. Therefore, potential water shortages and water conflict should be considered in the future because of spatiotemporal humidity variations in the NCP.

Empirical Equations to Estimate Evapotranspiration in Mosul City

2020 ◽  
Vol 27 (4) ◽  
pp. 98-102
Author(s):  
Haqqi Yasin ◽  
Luma Abdullah
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Air Temperature ◽  
Reference Evapotranspiration ◽  
Sunshine Duration ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Daily Data ◽  
Daily Sunshine ◽  
Measured Wind Speed

Average daily data of solar radiation, relative humidity, wind speed and air temperature from 1980 to 2008 are used to estimate the daily reference evapotranspiration in the Mosul City, North of Iraq. ETo calculator software with the Penman Monteith method standardized by the Food and Agriculture Organization is used for calculations. Further, a nonlinear regression approach using SPSS Statistics is utilized to drive the daily reference evapotranspiration relationships in which ETo is function to one or more of the average daily air temperature, actual daily sunshine duration, measured wind speed at 2m height and relative humidity

scholarly journals Long term monthly and inter-seasonal weather variability analysis for the lower Shivalik foothills of Punjab

MAUSAM ◽  
2022 ◽  
Vol 73 (1) ◽  
pp. 173-180
Author(s):  
NAVNEET KAUR ◽  
M.J. SINGH ◽  
SUKHJEET KAUR
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Linear Regression Method ◽  
Post Monsoon ◽  
Sunshine Hours ◽  
Annual Minimum Temperature ◽  
Weather Parameters

This paper aims to study the long-term trends in different weather parameters, i.e., temperature, rainfall, rainy days, sunshine hours, evaporation, relative humidity and temperature over Lower Shivalik foothills of Punjab. The daily weather data of about 35 years from agrometeorological observatory of Regional Research Station Ballowal Saunkhri representing Lower Shivalik foothills had been used for trend analysis for kharif (May - October), rabi (November - April), winter (January - February), pre-monsoon (March - May), monsoon (June - September) and post monsoon (October - December) season. The linear regression method has been used to estimate the magnitude of change per year and its coefficient of determination, whose statistical significance was checked by the F test. The annual maximum temperature, morning and evening relative humidity has increased whereas rainfall, evaporation sunshine hours and wind speed has decreased significantly at this region. No significant change in annual minimum temperature and diurnal range has been observed. Monthly maximum temperature revealed significant increase except January, June and December, whereas, monthly minimum temperature increased significantly for February, March and October and decreased for June. Among different seasons, maximum temperature increased significantly for all seasons except winter season, whereas, minimum temperature increased significantly for kharif and post monsoon season only. The evaporation, sunshine hours and wind speed have also decreased and relative humidity decreased significantly at this region. Significant reduction in kharif, monsoon and post monsoon rainfall has been observed at Lower Shivalik foothills. As the region lacks assured irrigation facilities so decreasing rainfall and change in the other weather parameters will have profound effects on the agriculture in this region so there is need to develop climate resilient agricultural technologies.

scholarly journals Hydro-climatic and land use/cover changes in Nasia catchment of the White Volta basin in Ghana

2021 ◽  
Author(s):  
Emmanuel Nyadzi ◽  
Enoch Bessah ◽  
Gordana Kranjac-Berisavljevic ◽  
Fulco Ludwig
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Resources ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Climatic Variables ◽  
Northern Ghana ◽  
Maximum Temperature

AbstractThe Nasia catchment is the reservoir with significant surface water resources in Northern Ghana and home to numerous subsistence farmers engaged in rainfed and dry season irrigation farming. Yet, there is little understanding of the hydro-climatic and land use/cover conditions of this basin. This study investigated trends, relationships and changes in hydro-climatic variables and land use/cover in addition to implications of the observable changes in the Nasia catchment over a period of 50 years. Parameters used for the study were minimum (Tmin) and maximum temperature (Tmax), wind speed (WS), sunshine duration (S), rainfall (R), relative humidity (RH), discharge (D) and potential evapotranspiration (PET) data, 15 years of remotely sensed normalized difference vegetation index (NDVI) data and 30 years of land use/cover image data. Results show that Tmin, Tmax, WS and PET have increased significantly (p < 0.05) over time. RH and S significantly declined. R, D and NDVI have not decreased significantly (p > 0.05). A significant abrupt change in almost all hydro-climatic variables started in the 1980s, a period that coincides with the occurrence of drought events in the region, except WS in 2001, R in 1968 and D in 1975, respectively. Also, D showed a positive significant correlation with RH, R and PET, but an insignificant positive relationship with S. D also showed a negative insignificant correlation with Tmin, Tmax and WS. Areas covered with shrubland and settlement/bare lands have increased to the disadvantage of cropland, forest, grassland and water bodies. It was concluded that climate change impact is quite noticeable in the basin, indicating water scarcity and possibilities of droughts. The analysis performed herein is a vital foundation for further studies to simulate and predict the effect of climate change on the water resources, agriculture and livelihoods in the Nasia catchment.

scholarly journals Spatiotemporal Distribution Characteristics of Reference Evapotranspiration in Shandong Province from 1980 to 2019

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3495
Author(s):  
Fujie Zhang ◽  
Zihan Liu ◽  
Lili Zhangzhong ◽  
Jingxin Yu ◽  
Kaili Shi ◽  
...  
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Agricultural Production ◽  
Reference Evapotranspiration ◽  
Water Cycle ◽  
Shandong Province ◽  
Spatiotemporal Variations ◽  
Sunshine Hours ◽  
Significant Downward Trend ◽  
Average Annual Temperature

Reference evapotranspiration (ET0) is an important part of the water cycle and energy cycle during crop growth. Understanding the influencing factors and spatiotemporal variations of ET0 can guide regional water-saving irrigation and regulate agricultural production. Data for daily meteorological observations of temperature, relative humidity, wind speed, and sunshine hours from 38 surface meteorological stations were used to analyze the spatiotemporal variations and trends in Shandong Province from 1980 to 2019. (1) The ET0 from 1980 to 2019 was 1070.5 mm, and there was a significant downward trend in the climate tendency rate of −7.92/10 a. The climate of Shandong Province became warmer and drier. The average annual temperature showed a significant upward trend, while the average annual relative humidity and average annual sunshine hours showed significant downward trends. (2) The annual ET0 ratio in spring, summer, autumn, and winter was 29%, 40%, 21%, and 10%, respectively. (3) A change in Shandong Province’s interannual ET0 occurred in 2002, with a decrease of 130.74 mm since then. (4) The ET0 was positively correlated with temperature, wind speed, and sunshine hours and negatively correlated with relative humidity. This study provides a scientific basis for the regulation and control of agricultural production in Shandong Province.

scholarly journals Changes of Reference Evapotranspiration and Its Relationships to Dry/Wet Conditions Based on Aridity Index in Songnen Grassland, Northeast China

2017 ◽  
Author(s):  
Qiyun Ma ◽  
Jiquan Zhang ◽  
Caiyun Sun ◽  
Enliang Guo ◽  
Feng Zhang ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Relative Humidity ◽  
Time Scales ◽  
Northeast China ◽  
Reference Evapotranspiration ◽  
Sunshine Duration ◽  
Aridity Index ◽  
Kendall Test ◽  
Positive Contribution ◽  
Different Time Scales

Reference evapotranspiration (ET0) plays an irreplaceable role in regional dry/wet conditions under the background of climate change. Based on the FAO Penman-Monteith method and daily climate variables, ET0 was calculated for 22 stations in and around Songnen Grassland, northeast China, during 1960-2014. The temporal and spatial variations of ET0 and precipitation (P) were comprehensively analyzed at different time scales by using the Mann-Kendall test, Sen&rsquo;s slope estimator, and linear regression coupling with break trend analysis. Sensitivity analysis was used to detect the key climate parameter attributed to ET0 change. Then, the role of ET0 in regional dry/wet conditions was discussed by analyzing the relationship between ET0, P and aridity index (AI). Results shown a higher ET0 in the southwest and a lower in the northeast, but P was opposite to that of ET0. Evidently decreasing trend of ET0 at different time scales was detected in almost the entire region, and the significant trend mainly distributed in the eastern, northeastern and central. For the whole region, sensitivity analysis indicated decreasing trend of ET0 was primarily attributed to relative humidity and maximum air temperature. The positive contribution of increasing temperature rising to ET0 was offset by the effect of significantly decreasing relative humidity, wind speed and sunshine duration. In addition, the value of ET0 shown higher in drought years and lower in wet years.

scholarly journals Influence of Weather Parameters and Thermal Time Approach on Green Gram at Coimbatore, Tamil Nadu

2020 ◽  
pp. 1-5
Author(s):  
S. A. Naveen ◽  
S. Kokilavani ◽  
S. P. Ramanathan ◽  
G. A. Dheebakaran ◽  
S. Anitta Fanish
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Tamil Nadu ◽  
Green Gram ◽  
Research Centre ◽  
Maximum Temperature ◽  
Sowing Dates ◽  
Sunshine Hours ◽  
Diurnal Range ◽  
Weather Parameters

An investigation was carried out at the Agro Climate Research Centre, Tamil Nadu Agricultural University, on the effect of weather parameters on the green gram yield sown at various sowing dates during the rabi season of 2019. At various sowing dates, two green gram cultivars, VBN 4 and ADT 3, were sown. For both cultivars, the phonological crop length decreased with delays in sowing dates beyond October 23rd. The yield of green gram sown on 23rd October was significantly higher than the crops sown on 30th October and 6th November. The weather parameters Maximum Temperature (Tmax), Diurnal Range (Trange), Bright Sunshine Hours (BSS), Relative Humidity (RH I), Wind Speed (WS) were found to be negatively correlated with seed yield whereas Minimum Temperature (Tmin), Relative Humidity (RH II), Vapour Pressure (VP) were found to be positively correlated with the yield of green gram. The accurate prediction of green gram yield could be done with the maximum temperature, bright sunshine hours, wind speed and with thermal indices especially hygrothermal unit II with 82 percent, accuracy level.

Trends of Estimated Potential Evapotranspiration in the Poyang Lake Basin, China

2013 ◽  
Vol 726-731 ◽  
pp. 3299-3302 ◽  
Author(s):  
Xu Chun Ye ◽  
Jian Liu ◽  
Qi Zhang
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Poyang Lake ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Lake Basin ◽  
Catchment Scale ◽  
Poyang Lake Basin ◽  
Autumn And Winter

Using the Penman-Monteith method, the potential evapotranspiration (PET) was calculated over the Poyang Lake basin during 1960-2008. Our analysis indicates that except spring, PET in summer, autumn and winter shows long term decreasing trend, with the largest in summer and the least in winter. The decrease of annual PET in the Poyang Lake basin is mostly affected by the decline of summer PET. On catchment scale, although the calculated PET at all the Metero-stations shows decrease trend, the trends are not significant at some stations. Further analysis indicates that the most important predictor for the decreasing trend in potential evapotranspiration is sunshine duration and wind speed, followed by relative humidity and air temperature.

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