Trends in Crop Reference Evapotranspiration and Climatological Variables Across Ceará State – Brazil

Abstract Irrigation has a substantial share in total world water demand. At the global level, the withdrawal ratio for agriculture is 69 percent. Irrigation is necessary to compensate evapotranspiration (ET) deficit due to insufficient precipitation. Knowing the impacts of climatic changes on meteorological variables that directly affect the ET is important for successful climate adaptation. This paper analyzes annual trends in measured meteorological variables and in the crop reference evapotranspiration (ET0), at eight climatological stations in Ceará State, Brazil. Two statistical tests for trend analysis were used - Mann-Kendall and linear regression. The results indicate positive trend, statistically significant, in the maximum air temperature in five of eight stations. Minimum air temperature showed positive trend in three stations. Wind speed, sunshine hours and relative humidity presented positive and negative trends. These irregular patterns directly impacted ET0 in three stations. It seems that the increasing trend in ET0 was probably due to a significant increase detected in maximum temperature and minimum air temperature, not fully offset by the decrease in wind speed and relative humidity. The warning from these results is that water demand for irrigation is expected to significantly increase over the next decades on in Jaguaribe River Basin.

Download Full-text

Empirical Equations to Estimate Evapotranspiration in Mosul City

Tikrit Journal of Engineering Sciences ◽

10.25130/tjes.27.4.10 ◽

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

Download Full-text

SEASONAL AND INTERANNUAL PATTERN OF METEOROLOGICAL VARIABLES IN CUIABÁ, MATO GROSSO STATE, BRAZIL

Brazilian Journal of Geophysics ◽

10.22564/rbgf.v33i3.949 ◽

2015 ◽

Vol 33 (3) ◽

pp. 477 ◽

Cited By ~ 2

Author(s):

Nadja Gomes Machado ◽

Marcelo Sacardi Biudes ◽

Carlos Alexandre Santos Querino ◽

Victor Hugo De Morais Danelichen ◽

Maísa Caldas Souza Velasque

Keyword(s):

Wind Speed ◽

Relative Humidity ◽

Meteorological Data ◽

Seasonal Pattern ◽

Global Radiation ◽

Meteorological Variables ◽

Maximum Temperature ◽

Wet Season ◽

Agricultural Producers ◽

Mato Grosso

ABSTRACT. Cuiab´a is located on the border of the Pantanal and Cerrado, in Mato Grosso State, which is recognized as one of the biggest agricultural producers of Brazil. The use of natural resources in a sustainable manner requires knowledge of the regional meteorological variables. Thus, the objective of this study was to characterize the seasonal and interannual pattern of meteorological variables in Cuiab´a. The meteorological data from 1961 to 2011 were provided by the Instituto Nacional de Meteorologia (INMET – National Institute of Meteorology). The results have shown interannual and seasonal variations of precipitation, solar radiation, air temperature and relative humidity, and wind speed and direction, establishing two main distinct seasons (rainy and dry). On average, 89% of the rainfall occurred in the wet season. The annual average values of daily global radiation, mean, minimum and maximum temperature and relative humidity were 15.6 MJ m–2 y–1, 27.9◦C, 23.0◦C, 30.0◦C and 71.6%, respectively. Themaximum temperature and the wind speed had no seasonal pattern. The wind speed average decreased in the NWdirectionand increased in the S direction.Keywords: meteorological variables, climatology, ENSO. RESUMO. Cuiabá está localizado na fronteira do Pantanal com o Cerrado, no Mato Grosso, que é reconhecido como um dos maiores produtores agrícolas do Brasil. A utilização dos recursos naturais de forma sustentável requer o conhecimento das variáveis meteorológicas em escala regional. Assim, o objetivo deste estudo foi caracterizar o padrão sazonal e interanual das variáveis meteorológicas em Cuiabá. Os dados meteorológicos de 1961 a 2011 foram fornecidos pelo Instituto Nacional de Meteorologia (INMET). Os resultados mostraram variações interanuais e sazonais de precipitação, radiação solar, temperatura e umidade relativa do ar e velocidade e direção do vento, estabelecendo duas principais estações distintas (chuvosa e seca). Em média, 89% da precipitação ocorreu na estação chuvosa. Os valores médios anuais de radiação diária global, temperatura do ar média, mínima e máxima e umidade relativa do ar foram 15,6 MJ m–2 y–1, 27,9◦C, 23,0◦C, 30,0◦C e 71,6%, respectivamente. A temperatura máxima e a velocidade do vento não tiveram padrão sazonal. A velocidade média do vento diminuiu na direção NW e aumentou na direção S.Palavras-chave: variáveis meteorológicas, climatologia, ENOS.

Download Full-text

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

Water ◽

10.3390/w12071957 ◽

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.

Download Full-text

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

FUOYE Journal of Engineering and Technology ◽

10.46792/fuoyejet.v3i2.221 ◽

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

Download Full-text

Sensitivity analysis of different evapotranspiration methods using a new sensitivity coefficient

Global NEST Journal ◽

10.30955/gnj.000882 ◽

2013 ◽

Vol 14 (3) ◽

pp. 335-343 ◽

Cited By ~ 3

Keyword(s):

Sensitivity Analysis ◽

Wind Speed ◽

Relative Humidity ◽

Solar Radiation ◽

Partial Derivative ◽

Reference Evapotranspiration ◽

Sensitivity Coefficient ◽

Meteorological Variables ◽

Sensitivity Coefficients ◽

Irrigation Period

The estimation of evapotranspiration is essential in water resources management. Among a group of methods, the Penman–Monteith has been commonly applied to calculate reference evapotranspiration as this method has been also recommended by the Food and Agriculture Organization of the U.N. (FAO). Other methods widely used are: the FAO 24 Penman, the modified Blaney and Criddle, the FAO 24 Makkink, and the Hargreaves. Sensitivity analysis is required to gain a better understanding of the meteorological systems; particularly to indicate the physical meaning of each meteorological parameter used in the estimation of the reference evapotranspiration. Several dimensionless sensitivity coefficients have been proposed, based on the partial derivative of the dependent variable (reference evapotranspiration) to the independent variables (meteorological variables). In this paper, a new sensitivity coefficient is proposed to drive sensitivity analysis of the evapotranspiration methods. The new sensitivity coefficient uses the partial derivative and the standard deviation of each independent variable. The meteorological variables, whose influence has been examined, are all the necessary meteorological parameters for the calculation of reference evapotranspiration, such as temperature, solar radiation, wind speed and relative humidity for each method. Data from the automatic meteorological station of Aminteo in the Prefecture of Florina, Western Macedonia, were used. The sensitivity coefficients were calculated for each month, year and irrigation period. The comparison of the sensitivity coefficients is performed for the month of water peak demand (July), the irrigation period and the year for each evapotranspiration method. Results show that the influence of the variables to evapotranspiration is not the same for each period, and also the order that the variables influence evapotranspiration is changing. A comparison between the five evapotranspiration methods shows that solar radiation and temperature are the main parameters that affect evapotranspiration, while relative humidity and wind speed are not so important for the calculation of evapotranspiration.

Download Full-text

The effect of meteorological conditions on hazel (Corylus spp.) and alder (Alnus spp.) pollen concentration in the air of Szczecin

Acta Agrobotanica ◽

10.5586/aa.2007.032 ◽

2012 ◽

Vol 60 (2) ◽

pp. 65-70 ◽

Cited By ~ 7

Author(s):

Małgorzata Puc

Keyword(s):

Wind Speed ◽

Relative Humidity ◽

Air Temperature ◽

Pollen Season ◽

Meteorological Parameters ◽

Meteorological Conditions ◽

Maximum Temperature ◽

Pollen Count ◽

Pollen Concentration ◽

In The Beginning

The aim of the study was to determine seasonal variations in concentrations of hazel and alder pollen count due to meteorological parameters. Measurements were performed using the volumetric method. The analysed meteorological parameters were the maximum temperature, relative humidity, rainfall and wind speed. The beginning and end of a season were established by the 95 % method. During seven years of study, the highest concentration of hazel pollen in the air was noted in 2003 (the total number was two - three times higher than in the other years), with the pollen season starting in most years in the beginning of January and lasting till the end of March or beginning of April. The highest concentration of alder pollen in the air was noted in 2003, similarly as hazel pollen. The pollen season started in the beginning of January (in 2003 and 2006 in the beginning of March) and lasted till the turn of the March and April. The highest pollen count of 674 grains×m<sup>-3</sup> was observed in the end of March. A positive and statistically signifi cant correlation (Pearson's coeffi cient and multiple regression) was found between the hazel and alder pollen concentration and air temperature and wind speed. A negative correlation was found in case of the relative humidity. A lot of analysed correlations were signifi cant (significance level of p=0.05), although the percentage of explained variation (R<sup>2</sup>) was very low. Besides the individual rhythm of pollination, the meteorological conditions are the most important factors (mainly air temperature and wind speed) influencing the analysed pollen concentration in the air.

Download Full-text

Trends in major climatic parameters and sensitivity of evapotranspiration to climatic parameters in the eastern Himalayan region of Sikkim, India

Journal of Water and Climate Change ◽

10.2166/wcc.2019.121 ◽

2019 ◽

Vol 11 (2) ◽

pp. 491-502

Author(s):

G. T. Patle ◽

D. Sengdo ◽

M. Tapak

Keyword(s):

Sensitivity Analysis ◽

Wind Speed ◽

Relative Humidity ◽

Minimum Temperature ◽

Reference Evapotranspiration ◽

Himalayan Region ◽

Series Data ◽

Maximum Temperature ◽

Climatic Parameters ◽

Eastern Himalayan Region

Abstract In this study, temporal trends in daily time series data of key climatic parameters were analyzed using Mann–Kendall and Sen's slope estimator. Sensitivity analysis of each climatic parameter on reference evapotranspiration (ETo) was performed to estimate the sensitivity coefficients and to evaluate the impact of global warming on ETo in the eastern Himalayan region of Sikkim, India. Results of trend analysis showed a significant increasing trend for minimum temperature and mean temperature. Mean relative humidity and sunshine duration showed decreasing trends. Reference evapotranspiration also showed a significant decreasing trend by 0.008 mm year–1 in Sikkim state of India. Sensitivity analysis revealed that the seasonal and annual ETo were most sensitive to maximum temperature followed by sunshine hours whereas wind speed, minimum temperature and relative humidity had a fluctuating effect on mean ETo. The sensitivity coefficient indicated that ETo changes positively with maximum and minimum temperature, sunshine hour, and wind speed, while it changes negatively with relative humidity. Analysis indicated that increase in relative humidity would decrease the ETo in the study area. The findings of this study would be useful for sustainable water resources planning and management of agriculture in hilly regions of the state and for development of adaptation strategies in adverse climatic conditions.

Download Full-text

Potential influence of meteorological variables on forest fire risk in Serbia during the period 2000-2017

Open Geosciences ◽

10.1515/geo-2019-0033 ◽

2019 ◽

Vol 11 (1) ◽

pp. 414-425 ◽

Cited By ~ 3

Author(s):

I. Tošić ◽

D. Mladjan ◽

M. B. Gavrilov ◽

S. Živanović ◽

M. G. Radaković ◽

...

Keyword(s):

Wind Speed ◽

Relative Humidity ◽

Forest Fires ◽

Fire Risk ◽

Weather Conditions ◽

Meteorological Variables ◽

Maximum Temperature ◽

Air Temperatures ◽

Input Variables ◽

Forest Fire Risk

Abstract To examine potential relationships between meteorological variables and forest fires in Serbia, daily temperature, precipitation, relative humidity and wind speed data for 15 meteorological stations across Serbia were used to construct fire indices. The daily values of the Ångström and Nesterov indices were calculated for the period 2000–2017. A high number of forest fires occurred in 2007 and 2012 in Serbia, during a period of extremely high air temperatures in 2007, followed by the longest heat wave and the worst drought in 2012. In order to identify the ideal weather conditions for fire break outs, different combinations of input variables, e.g., meteorological variables (mean temperature, precipitation, relative humidity, maximum temperature, minimum temperature and wind speed), fire danger indices or a combination of both, for the Belgrade area during the period 1986–2017, were tested. It was found that using relative humidity or precipitation as a predictor only generates a satisfactory model for forecasting of number of forest fires.

Download Full-text

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

Journal of Water and Climate Change ◽

10.2166/wcc.2015.217 ◽

2015 ◽

Vol 7 (1) ◽

pp. 128-141 ◽

Cited By ~ 2

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.

Download Full-text

Detrended Multiple Cross-Correlation Coefficient applied to solar radiation, air temperature and relative humidity

Scientific Reports ◽

10.1038/s41598-019-56114-6 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Andrea de Almeida Brito ◽

Heráclio Alves de Araújo ◽

Gilney Figueira Zebende

Keyword(s):

Relative Humidity ◽

Solar Radiation ◽

Solar Energy ◽

Correlation Coefficient ◽

Air Temperature ◽

Cross Correlation ◽

Global Solar Radiation ◽

Meteorological Variables ◽

Hourly Data ◽

Cross Correlations

AbstractDue to the importance of generating energy sustainably, with the Sun being a large solar power plant for the Earth, we study the cross-correlations between the main meteorological variables (global solar radiation, air temperature, and relative air humidity) from a global cross-correlation perspective to efficiently capture solar energy. This is done initially between pairs of these variables, with the Detrended Cross-Correlation Coefficient, ρDCCA, and subsequently with the recently developed Multiple Detrended Cross-Correlation Coefficient, $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2. We use the hourly data from three meteorological stations of the Brazilian Institute of Meteorology located in the state of Bahia (Brazil). Initially, with the original data, we set up a color map for each variable to show the time dynamics. After, ρDCCA was calculated, thus obtaining a positive value between the global solar radiation and air temperature, and a negative value between the global solar radiation and air relative humidity, for all time scales. Finally, for the first time, was applied $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2 to analyze cross-correlations between three meteorological variables at the same time. On taking the global radiation as the dependent variable, and assuming that $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}={\bf{1}}$$DMCx2=1 (which varies from 0 to 1) is the ideal value for the capture of solar energy, our analysis finds some patterns (differences) involving these meteorological stations with a high intensity of annual solar radiation.

Download Full-text