scholarly journals A 10-Year Dataset of Basic Meteorology and Soil Properties in Central Sudan

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jonas Ardö
Keyword(s):  
Soil Properties ◽  
Meteorological Data ◽  
Global Radiation ◽  
Semiarid Region ◽  
Net Radiation ◽  
Ecosystem Models ◽  
Central Sudan ◽  
General Data ◽  
A Site ◽  
Temperature Water

Meteorological data and soil data have been collected at a site in the central Sudan from 2002 to 2012. The site is a sparse savanna in the semiarid region of Sudan. In addition to basic meteorological variables, soil properties (temperature, water content, and heat flux) and radiation (global radiation, net radiation, and photosynthetic active radiation) were measured. The dataset has a temporal resolution of 30 minutes and provides general data for calibration and validation of ecosystem models and remote-sensing-based assessments, and it is relevant for studies of ecosystem properties and processes.

scholarly journals A Thermodynamically Based Model for Actual Evapotranspiration of an Extensive Grass Field Close to FAO Reference, Suitable for Remote Sensing Application

2016 ◽  
Vol 17 (5) ◽  
pp. 1373-1382 ◽  
Author(s):  
H. A. R. de Bruin ◽  
I. F. Trigo ◽  
F. C. Bosveld ◽  
J. F. Meirink
Keyword(s):  
Global Radiation ◽  
Actual Evapotranspiration ◽  
Net Radiation ◽  
Reference Crop Evapotranspiration ◽  
In Situ Data ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
A Site ◽  
Reference Crop

Abstract A thermodynamically based model is presented to estimate daily actual evapotranspiration (ET) of a grass site closely resembling reference grass as defined by the Food and Agriculture Organization of the United Nations (FAO) under nonadvective conditions, from Meteosat Second Generation (MSG) imagery. The model presented here is derived from the thermodynamic theory by Schmidt combined with an atmospheric boundary layer model. Daily net radiation over the (reference) grass surface is parameterized as a function of global radiation, which can be estimated from MSG observations. It is then shown that ET over the grass area can be estimated using remotely sensed daily global radiation and air temperature as input only. The validation relied on observations gathered in Cabauw, a site closely resembling the reference grass, as defined by the FAO. The comparison with in situ data indicated a bias of 2.8 W m−2 and an RMSE of 7.7 W m−2. The possibility of using the approach developed here to provide reference crop evapotranspiration ETo is discussed. Because of the ambiguousness of ETo definition regarding local advection effects, it should be noted that explicitly advection-free conditions are dealt with. It is pointed out that in semiarid regions local advection cannot be ignored.

Evapotranspiration measurements in the Brazilian Caatinga dry forest

2021 ◽  
Author(s):  
José Carlos de Araújo ◽  
Lucas Melo Vellame ◽  
Armin Raabe ◽  
Quirijn de Jong van Lier
Keyword(s):  
Water Availability ◽  
Global Radiation ◽  
Dry Season ◽  
Dry Forest ◽  
Actual Evapotranspiration ◽  
Semiarid Region ◽  
Application Site ◽  
Net Radiation ◽  
Simple Method ◽  
The North

<p>The Brazilian semiarid region (one million km²) is densely populated (25 million inhabitants), but its natural water availability is low. Despite the fact that evaporative processes are key to the regional water deficit, the actual evapotranspiration of natural environment has rarely been measured, especially in the native Caatinga dry forest. We hereby propose a simple method that demands the monitoring of five meteorological variables: relative humidity, global radiation, canopy and air temperature, as well as wind speed. These values are used to assess leaf energy balance, yielding net radiation (Rn) and actual evapotranspiration (LE). To estimate the actual Caatinga evapotranspiration under natural conditions and in different seasons, the proposed method was applied <em>in situ</em> during nine months. The application site was the Aiuaba Experimental Basin, situated in an environmental protection area in the North-eastern Brazil. The method provided consistent results when compared with independent measurements, such as atmospheric demand, leaf area, and soil water content variation. Results indicate that the daily average net radiation is 12 MJ m<sup>-</sup>². During the dry season, the actual evapotranspiration is very low, with negligible LE/Rn ratio. Contrastingly, in the rainy season, it raises to 6 mm per day, with average LE/Rn ratio equalling 0.89. The results show that the actual evapotranspiration in the Caatinga long-lasting dry season (up to nine months per year) is controlled by the water availability in the soil.</p>

Applying the Method of Lagrange Multipliers to Derive an Estimator for Unsampled Soil Properties

2014 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Set Foong Ng ◽  
Pei Eng Ch’ng ◽  
Yee Ming Chew ◽  
Kok Shien Ng
Keyword(s):  
Soil Properties ◽  
Lagrange Multipliers ◽  
Unbiased Estimator ◽  
Soil Property ◽  
Minimum Variance ◽  
Distance Method ◽  
True Value ◽  
A Site ◽  
Method Of Lagrange Multipliers ◽  
Inverse Distance

Soil properties are very crucial for civil engineers to differentiate one type of soil from another and to predict its mechanical behavior. However, it is not practical to measure soil properties at all the locations at a site. In this paper, an estimator is derived to estimate the unknown values for soil properties from locations where soil samples were not collected. The estimator is obtained by combining the concept of the ‘Inverse Distance Method’ into the technique of ‘Kriging’. The method of Lagrange Multipliers is applied in this paper. It is shown that the estimator derived in this paper is an unbiased estimator. The partiality of the estimator with respect to the true value is zero. Hence, the estimated value will be equal to the true value of the soil property. It is also shown that the variance between the estimator and the soil property is minimised. Hence, the distribution of this unbiased estimator with minimum variance spreads the least from the true value. With this characteristic of minimum variance unbiased estimator, a high accuracy estimation of soil property could be obtained.

Corrigendum to: Conservation agriculture effects on soil properties and crop productivity in a semiarid region of India

Soil Research ◽  
2019 ◽  
Vol 57 (2) ◽  
pp. 200 ◽  
Author(s):  
J. Somasundaram ◽  
M. Salikram ◽  
N. K. Sinha ◽  
M. Mohanty ◽  
R. S. Chaudhary ◽  
...  
Keyword(s):  
Soil Properties ◽  
Management Practices ◽  
Crop Yields ◽  
Cropping Systems ◽  
Soil Layer ◽  
Conservation Agriculture ◽  
Semiarid Region ◽  
Reduced Tillage ◽  
Organic C ◽  
Residue Retention

Conservation agriculture (CA) including reduced or no-tillage and crop residue retention, is known to be a self–sustainable system as well as an alternative to residue burning. The present study evaluated the effect of reduced tillage coupled with residue retention under different cropping systems on soil properties and crop yields in a Vertisol of a semiarid region of central India. Two tillage systems – conventional tillage (CT) with residue removed, and reduced tillage (RT) with residue retained – and six major cropping systems of this region were examined after 3 years of experimentation. Results demonstrated that soil moisture content, mean weight diameter, percent water stable aggregates (>0.25mm) for the 0–15cm soil layer were significantly (Pmoderately labile>less labile. At the 0–15cm depth, the contributions of moderately labile, less labile and non-labile C fractions to total organic C were 39.3%, 10.3% and 50.4% respectively in RT and corresponding values for CT were 38.9%, 11.7% and 49.4%. Significant differences in different C fractions were observed between RT and CT. Soil microbial biomass C concentration was significantly higher in RT than CT at 0–15cm depth. The maize–chickpea cropping system had significantly (P–1 followed by soybean+pigeon pea (2:1) intercropping (3.50 t ha–1) and soybean–wheat cropping systems (2.97 t ha–1). Thus, CA practices could be sustainable management practices for improving soil health and crop yields of rainfed Vertisols in these semiarid regions.

scholarly journals Using the SWEPT Methodology for a Preliminary Wind Potential Estimation

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Jean-Luc Menet
Keyword(s):  
Wind Turbine ◽  
Characteristic Curve ◽  
Rayleigh Distribution ◽  
Mean Velocity ◽  
Technical Data ◽  
Wind Potential ◽  
Order Of Magnitude ◽  
General Data ◽  
The Mean ◽  
A Site

The implantation of wind turbines generally follows a wind potential study which is made using specific numerical tools; the generated expenses are only acceptable for great projects. The purpose of the present paper is to propose a simplified methodology for the evaluation of the wind potential, following three successive steps for the determination of (i) the mean velocity, either directly or by the use of the most occurrence velocity (MOV); (ii) the velocity distribution coming from the single knowledge of the mean velocity by the use of a Rayleigh distribution and a Davenport-Harris law; (iii) an appropriate approximation of the characteristic curve of the turbine, coming from only two technical data. These last two steps allow calculating directly the electric delivered energy for the considered wind turbine. This methodology, called the SWEPT approach, can be easily implemented in a single worksheet. The results returned by the SWEPT tool are of the same order of magnitude than those given by the classical commercial tools. Moreover, everybody, even a “neophyte,” can use this methodology to obtain a first estimation of the wind potential of a site considering a given wind turbine, on the basis of very few general data.

scholarly journals Reference evapotranspiration for Londrina, Paraná, Brazil: performance of different estimation methods

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2363
Author(s):  
Rodrigo Dlugosz da Silva ◽  
Marcelo Augusto de Aguiar e Silva ◽  
Marcelo Giovanetti Canteri ◽  
Juliandra Rodrigues Rosisca ◽  
Nilson Aparecido Vieira Junior
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Global Radiation ◽  
Alternative Methods ◽  
Estimation Methods ◽  
Performance Indices ◽  
Excellent Performance ◽  
Study Region ◽  
Temperature Radiation ◽  
And Performance

Aiming at assessing the performance of alternative methods to Penman-Monteith FAO56 for estimating the reference evapotranspiration (ETo) for Londrina, Paraná, Brazil, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tanner-Pelton, Jensen-Haise, Makkink, modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, Linacre, Blaney-Morin, Romanenko, Hargreaves (1974), McCloud, Camargo, Hamon, Kharrufa, McGuiness-Bordne, and Blaney-Criddle were compared to that standard method recommended by FAO. The estimations were correlated by linear regression and assessed by using the Person’s correlation coefficient (r), concordance index (d), and performance index (c) using a set of meteorological data of approximately 40 years. The methods modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, and Linacre should be avoided, as they did not present excellent results. The methods McCloud, Camargo, Hamon, Kharrufa, McGuinness-Bordne, Blaney-Criddle, Hargreaves (1974), Romanenko, and Blaney-Morin were classified as very bad, not being recommended. In contrast, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tenner-Pelton, Jensen-Haise, and Makkink presented excellent performance indices and can be applied in the study region.

scholarly journals Reference evapotranspiration for Londrina, Paraná, Brazil: performance of different estimation methods

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2363
Author(s):  
Rodrigo Dlugosz da Silva ◽  
Marcelo Augusto de Aguiar e Silva ◽  
Marcelo Giovanetti Canteri ◽  
Juliandra Rodrigues Rosisca ◽  
Nilson Aparecido Vieira Junior
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Global Radiation ◽  
Alternative Methods ◽  
Estimation Methods ◽  
Performance Indices ◽  
Excellent Performance ◽  
Study Region ◽  
Temperature Radiation ◽  
And Performance

Aiming at assessing the performance of alternative methods to Penman-Monteith FAO56 for estimating the reference evapotranspiration (ETo) for Londrina, Paraná, Brazil, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tanner-Pelton, Jensen-Haise, Makkink, modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, Linacre, Blaney-Morin, Romanenko, Hargreaves (1974), McCloud, Camargo, Hamon, Kharrufa, McGuiness-Bordne, and Blaney-Criddle were compared to that standard method recommended by FAO. The estimations were correlated by linear regression and assessed by using the Person’s correlation coefficient (r), concordance index (d), and performance index (c) using a set of meteorological data of approximately 40 years. The methods modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, and Linacre should be avoided, as they did not present excellent results. The methods McCloud, Camargo, Hamon, Kharrufa, McGuinness-Bordne, Blaney-Criddle, Hargreaves (1974), Romanenko, and Blaney-Morin were classified as very bad, not being recommended. In contrast, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tenner-Pelton, Jensen-Haise, and Makkink presented excellent performance indices and can be applied in the study region.

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

2015 ◽  
Vol 33 (3) ◽  
pp. 477 ◽  
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.

scholarly journals Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data

2019 ◽  
Vol 23 (12) ◽  
pp. 4891-4907 ◽  
Author(s):  
Robert N. Armstrong ◽  
John W. Pomeroy ◽  
Lawrence W. Martz
Keyword(s):  
Remote Sensing ◽  
Spatial Variability ◽  
Land Surface ◽  
Management Practices ◽  
Reference Data ◽  
Meteorological Data ◽  
Net Radiation ◽  
Study Region ◽  
Evaporation Model ◽  
Actual Evaporation

Abstract. Land surface evaporation has considerable spatial variability that is not captured by point-scale estimates calculated from meteorological data alone. Knowing how evaporation varies spatially remains an important issue for improving parameterisations of land surface schemes and hydrological models and various land management practices. Satellite-based and aerial remote sensing has been crucial for capturing moderate- to larger-scale surface variables to indirectly estimate evaporative fluxes. However, more recent advances for field research via unmanned aerial vehicles (UAVs) now allow for the acquisition of more highly detailed surface data. Integrating models that can estimate “actual” evaporation from higher-resolution imagery and surface reference data would be valuable to better examine potential impacts of local variations in evaporation on upscaled estimates. This study introduces a novel approach for computing a normalised ratiometric index from surface variables that can be used to obtain more-realistic distributed estimates of actual evaporation. For demonstration purposes the Granger–Gray evaporation model (Granger and Gray, 1989) was applied at a rolling prairie agricultural site in central Saskatchewan, Canada. Visible and thermal images and meteorological reference data required to parameterise the model were obtained at midday. Ratiometric indexes were computed for the key surface variables albedo and net radiation at midday. This allowed point observations of albedo and mean daily net radiation to be scaled across high-resolution images over a large study region. Albedo and net radiation estimates were within 5 %–10 % of measured values. A daily evaporation estimate for a grassed surface was 0.5 mm (23 %) larger than eddy covariance measurements. Spatial variations in key factors driving evaporation and their impacts on upscaled evaporation estimates are also discussed. The methods applied have two key advantages for estimating evaporation over previous remote-sensing approaches: (1) detailed daily estimates of actual evaporation can be directly obtained using a physically based evaporation model, and (2) analysis of more-detailed and more-reliable evaporation estimates may lead to improved methods for upscaling evaporative fluxes to larger areas.

scholarly journals Delineation of irrigation management zones in a Quartzipsamment of the Brazilian semiarid region

2016 ◽  
Vol 51 (9) ◽  
pp. 1283-1294 ◽  
Author(s):  
Henrique Oldoni ◽  
Luís Henrique Bassoi
Keyword(s):  
Soil Properties ◽  
Clustering Algorithm ◽  
Irrigation Management ◽  
Optimal Number ◽  
Semiarid Region ◽  
Management Zones ◽  
Distribution Maps ◽  
Management Zone ◽  
Brazilian Semiarid ◽  
Fuzzy C Means Clustering

Abstract The objective of this work was to delineate irrigation management zones using geostatistics and multivariate analysis in different combinations of physical and hydraulic soil properties, as well as to determine the optimal number of management zones in order to avoid overlaping. A field experiment was carried out in a Quartzipsamment, for two years, in an irrigated orchard of table grape, in the Senador Nilo Coelho Irrigation Scheme, in the municipality of Petrolina, in the state of Pernanbuco, Brazil. Soil samples were collected for the determination of soil physico-hydraulic properties. A portable meter was used to measure soil apparent electrical conductivity. Spatial distribution maps were generated using ordinary kriging. Management zones for five different combinations of soil properties were defined using the fuzzy c-means clustering algorithm, and two indexes were applied to determine the optimal number of management zones. Two combinations of soil properties can be used in the management zone planning in order to monitor soil moisture.

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