scholarly journals Spatial and temporal variation of reference evapotranspiration under climate change: a case study in the Sanjiang Plain, Northeast China

2017 ◽  
Vol 49 (1) ◽  
pp. 251-265 ◽  
Author(s):  
Xinyi Song ◽  
Kui Zhu ◽  
Fan Lu ◽  
Weihua Xiao
Keyword(s):  
Sensitivity Analysis ◽  
Wind Speed ◽  
Reference Evapotranspiration ◽  
Sunshine Duration ◽  
Meteorological Data ◽  
Negative Influence ◽  
Sanjiang Plain ◽  
Spatial And Temporal Variation ◽  
The Sanjiang Plain ◽  
Mountainous Regions

Abstract It is essential to understand the changing patterns in reference evapotranspiration (ET0) and its relation to climate variables. In this study, meteorological data obtained from the Sanjiang Plain (SJP) between 1959 and 2013 are used to calculate ET0 via the Penman–Monteith method. This study analyses the spatial and temporal changes of ET0 and determines which meteorological variables have an impact on this. The Mann–Kendall test, moving t-test, sensitivity analysis and simulated results have been used to conduct these analyses. The results demonstrate the following. (1) Spatially, there is an increasing trend in the annual ET0 values in agricultural areas. However, significant decreasing trends (P < 0.05) can be found in mountainous regions. (2) Temporally, two abrupt changes can be detected in the early 1980s and the late 1990s for the entire SJP, leading to large inter-annual differences. (3) Sensitivity analysis shows that relative humidity (RH) is the most sensitive climate variable and has a negative influence on ET0, followed by temperature, sunshine duration and wind speed, all of which exert positive impacts. (4) The simulated result shows that ET0 is most sensitive to RH. However, significant reductions in wind speed can exert large influences on the ET0 values.

scholarly journals Analysis of Ozone Pollution Characteristics and Influencing Factors in Northeast Economic Cooperation Region, China

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 843
Author(s):  
Jiaqi Tian ◽  
Chunsheng Fang ◽  
Jiaxin Qiu ◽  
Ju Wang
Keyword(s):  
Wind Speed ◽  
Sunshine Duration ◽  
Meteorological Data ◽  
Economic Cooperation ◽  
Ozone Pollution ◽  
Temporal And Spatial Variation ◽  
Temporal And Spatial ◽  
Pm2.5 And Pm10 ◽  
Peak Pattern ◽  
Pm2.5 Concentration

The increase in tropospheric ozone (O3) concentration has become one of the factors restricting urban development. This paper selected the important economic cooperation areas in Northeast China as the research object and collected the hourly monitoring data of pollutants and meteorological data in 11 cities from 1 January 2015 to 31 December 2019. The temporal and spatial variation trend of O3 concentration and the effects of meteorological factors and other pollutants, including CO (carbon monoxide), SO2 (sulfur dioxide), NO2 (nitrogen dioxide), and PM2.5 and PM10 (PM particles with aerodynamic diameters less than 2.5 μm and 10 μm) on ozone concentration were analyzed. At the same time, the variation period of O3 concentration was further analyzed by Morlet wavelet analysis. The results showed that the O3 pollution in the study area had a significant spatial correlation. The spatial distribution showed that the O3 concentration was relatively high in the south and low in the northeast. Seasonally, the O3 concentration was the highest in spring, followed by summer, and the lowest in winter. The diurnal variation of O3 concentration presented a “single peak” pattern. O3 concentration had a significant positive correlation with temperature, sunshine duration, and wind speed and a significant anticorrelation with CO, NO2, SO2, and PM2.5 concentration. Under the time scale of a = 9, 23, O3 had significant periodic fluctuation, which was similar to those of wind speed and temperature.

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 Performance of different methods for reference evapotranspiration estimation in Jaíba, Brazil

2018 ◽  
Vol 22 (2) ◽  
pp. 83-89 ◽  
Author(s):  
Gustavo H. da Silva ◽  
Santos H. B. Dias ◽  
Lucas B. Ferreira ◽  
Jannaylton É. O. Santos ◽  
Fernando F. da Cunha
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Standard Method ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Air Humidity ◽  
Method Performance ◽  
Relative Air Humidity ◽  
Evapotranspiration Estimation ◽  
Missing Variables

ABSTRACT FAO Penman-Monteith (FO-PM) is considered the standard method for the estimation of reference evapotranspiration (ET0) but requires various meteorological data, which are often not available. The objective of this work was to evaluate the performance of the FAO-PM method with limited meteorological data and other methods as alternatives to estimate ET0 in Jaíba-MG. The study used daily meteorological data from 2007 to 2016 of the National Institute of Meteorology’s station. Daily ET0 values were randomized, and 70% of these were used to determine the calibration parameters of the ET0 for the equations of each method under study. The remaining data were used to test the calibration against the standard method. Performance evaluation was based on Willmott’s index of agreement, confidence coefficient and root-mean-square error. When one meteorological variable was missing, either solar radiation, relative air humidity or wind speed, or in the simultaneous absence of wind speed and relative air humidity, the FAO-PM method showed the best performances and, therefore, was recommended for Jaíba. The FAO-PM method with two missing variables, one of them being solar radiation, showed intermediate performance. Methods that used only air temperature data are not recommended for the region.

scholarly journals Sensitivity analysis of the meteorological preprocessor MPP-FMI 3.0 using algorithmic differentiation

2017 ◽  
Vol 10 (10) ◽  
pp. 3793-3803 ◽  
Author(s):  
John Backman ◽  
Curtis R. Wood ◽  
Mikko Auvinen ◽  
Leena Kangas ◽  
Hanna Hannuniemi ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Wind Speed ◽  
Friction Velocity ◽  
Meteorological Data ◽  
Solar Irradiation ◽  
Obukhov Length ◽  
Algorithmic Differentiation ◽  
Model Input ◽  
Input Parameters ◽  
Meteorological Input

Abstract. The meteorological input parameters for urban- and local-scale dispersion models can be evaluated by preprocessing meteorological observations, using a boundary-layer parameterisation model. This study presents a sensitivity analysis of a meteorological preprocessor model (MPP-FMI) that utilises readily available meteorological data as input. The sensitivity of the preprocessor to meteorological input was analysed using algorithmic differentiation (AD). The AD tool used was TAPENADE. The AD method numerically evaluates the partial derivatives of functions that are implemented in a computer program. In this study, we focus on the evaluation of vertical fluxes in the atmosphere and in particular on the sensitivity of the predicted inverse Obukhov length and friction velocity on the model input parameters. The study shows that the estimated inverse Obukhov length and friction velocity are most sensitive to wind speed and second most sensitive to solar irradiation. The dependency on wind speed is most pronounced at low wind speeds. The presented results have implications for improving the meteorological preprocessing models. AD is shown to be an efficient tool for studying the ranges of sensitivities of the predicted parameters on the model input values quantitatively. A wider use of such advanced sensitivity analysis methods could potentially be very useful in analysing and improving the models used in atmospheric sciences.

scholarly journals The Effect of Climate Change on Variations in Dew Amount in a Paddy Ecosystem of the Sanjiang Plain, China

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Yingying Xu ◽  
Baixing Yan ◽  
Jie Tang
Keyword(s):  
Global Warming ◽  
Relative Humidity ◽  
Meteorological Data ◽  
Warming Trend ◽  
Sanjiang Plain ◽  
Dew Point ◽  
The Sanjiang Plain ◽  
Growing Seasons ◽  
Paddy Ecosystem ◽  
Dew Amount

Due to global warming, a drying and warming trend has been observed over the last 50 years in the Sanjiang Plain of Heilongjiang Province, China, which could significantly affect the condensation of vapor in paddy ecosystems. Dew is a crucial factor in the water and nutrient cycling of farmland ecosystems, and it exerts an important influence on fertilization and other agricultural activities. In order to reveal the effects of global warming on dew variation in a paddy ecosystem, anin situexperiment was conducted in paddy fields in the Sanjiang Plain during the growing seasons of 2011 to 2013. Dew was collected and measured with a poplar stick. The results of correlation analysis between meteorological factors and dew intensity in the paddy ecosystem indicate that the dew point temperature and relative humidity significantly influenced the dew intensity. Based on synchronous meteorological data, a stepwise linear multivariation regression model was established to predict dew amount. The model successfully interpreted the relationship between simulated and measured dew intensity. The results suggest that a warmer and drier climate would lead to a reduction in dew amount because water cannot condense when relative humidity falls below 71%.

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’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.

Variations and Sensitivity Analysis of Reference Evapotranspiration During 2010-2019 in the Zhangye Farmland Oasis, Northwest China

2021 ◽  
Author(s):  
Miao Fang
Keyword(s):  
Sensitivity Analysis ◽  
Reference Evapotranspiration ◽  
Sunshine Duration ◽  
Northwest China ◽  
Meteorological Factor ◽  
Maximum Temperature ◽  
Regression Equations ◽  
Significance Level ◽  
Hargreaves Equation ◽  
Increasing Trends

Abstract Reference evapotranspiration (ET0) is an important parameter for agricultural water management in the arid Zhangye farmland oasis. However, the ET0 variations in this oasis over the last decade and meteorological forcings of these variations are unknown. This study investigated the ET0 variations during 2010-2019 in this oasis using the FAO-56 Penman-Monteith (PM) and Hargreaves equations. Results showed that the ET0 features daily and monthly variations with peak values in mid-July and an annual cycle. Although the estimated ET0 series based on the two equations have high correlations in the time domain, the Hargreaves equation always underestimates the ET0 compared to the PM equation. The yearly ET0 showed statistically significant increasing trends (90% significance level) during 2010-2019, while statistically significant increasing trends in monthly ET0 are found only in March and November. Increasing trends reflected in monthly and yearly ET0 are mainly attributed to the increasing maximum temperature and sunshine duration and decreasing relative humidity. Sensitivity analysis demonstrated that the meteorological factor to which the ET0 is most sensitive varies with time scale and equation. Moreover, regression equations used to correct the underestimation associated with the Hargreaves equation for estimating ET0 in the Zhangye farmland oasis also were constructed.

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.

Variation Characteristics of PM10 Mass Concentrations and Correlations with Meteorological Factors in Xingtai City

2013 ◽  
Vol 807-809 ◽  
pp. 73-76
Author(s):  
Jian Wang ◽  
Mei Xu ◽  
Xia Ye ◽  
Wei Liu
Keyword(s):  
Wind Speed ◽  
Vapor Pressure ◽  
Negative Correlation ◽  
Mass Concentration ◽  
Meteorological Factors ◽  
Sunshine Duration ◽  
Meteorological Data ◽  
Air Pressure ◽  
Positive Correlation ◽  
Variation Characteristics

Based on monitoring data of air pollution index (API) and meteorological data from January 2009 to December 2012 in Xingtai, the variation characteristics of PM10mass concentration were analyzed and the relationships between PM10mass concentration and air pressure, wind speed, temperature, vapor pressure, relative humid and sunshine duration were investigated for four seasons using SPSS software. The results showed that the PM10mass concentration was 86.5, 83.3, 85.0 and 80.4 μg m­3, and the differences were not obvious tending to be a weak downward trend from 2009 to 2012. The percentage of the excellent and good air quality was high during the period and the mild and light pollution mainly appeared in December. The PM10mass concentration showed significant seasonal variations with a higher value in winter and fall and a lower value in spring and summer. The relationship between PM10mass concentration and meteorological factors showed some differences in different seasons. The PM10mass concentration had negative correlation with air pressure and sunshine duration and positive correlation with vapor pressure, temperature and wind speed in spring. The PM10mass concentration was negatively correlated with air pressure and sunshine duration, but positively correlated with vapor pressure and temperature in summer. The PM10mass concentration was negatively correlated with temperature, wind speed, vapor pressure and sunshine duration in fall. The PM10mass concentration had negative correlation with wind speed, sunshine duration and air pressure and positive correlation with vapor pressure and relative humidity in winter.

scholarly journals Reference Evapotranspiration (ETo) Methods Implemented as ArcMap Models with Remote-Sensed and Ground-Based Inputs, Examined along with MODIS ET, for Peloponnese, Greece

2021 ◽  
Vol 10 (6) ◽  
pp. 390
Author(s):  
Stavroula Dimitriadou ◽  
Konstantinos G. Nikolakopoulos
Keyword(s):  
Climate Change ◽  
Wind Speed ◽  
Water Availability ◽  
Physical Meaning ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Mediterranean Area ◽  
National Observatory ◽  
Evaporative Demand ◽  
Time Saving

The present study develops ArcMap models to implement the following three methods: FAO-56 Penman–Monteith (FAO PM), Hargreaves–Samani (HS) and Hansen, with the former used as a reference. Moreover, three models implementing statistical indices (RMSD, MB, NMB) are also created. The purpose is threefold, as follows: to investigate the variability in the daily mean reference evapotranspiration (ETo) for the Decembers and Augusts during 2016–2019, over Peloponnese, Greece. Furthermore, to investigate the agreement between the methods’ ETo estimates, and examine the former along with MODIS ET (daily) averaged products. The study area is a complex Mediterranean area. Meteorological data from sixty-two stations under the National Observatory of Athens (NOA), and MODIS Terra LST products, have been employed. FAO PM is found sensitive to wind speed and depicts interactions among climate parameters (T, evaporative demand and water availability) in the frame of climate change. The years 2016–2019 are four of the warmest since the preindustrial era. Hargreaves–Samani’s estimations for the Decembers of 2016–2019 were almost identical to MODIS ET, despite their different physical meaning. However, for the Augusts there are considerable discrepancies between the methods’ and MODIS’s estimates, attributed to the higher evaporative demand in the summertime. The GIS models are accurate, reliable, time-saving, and adjustable to any study area.

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