Abstract
In agrometeorology, reference surface consists of those traditional grass cover on weather stations. Net radiation (Rn) of this surface is an important information that has many applicability, but its measurement is rare due to the high cost of the sensor and the complexity involved on the measurement. Therefore, estimate Rn from another variable is desirable, as from solar radiation (Rs); however, standard methods used are complex, making interesting the use of simplified methodologies. Considering these aspects, the present study aimed to set two empirical methods to estimate Rn from Rs for Dourados region, located in the Mato Grosso do Sul State, Brazil. One method was set with a scientific purpose (Gauss Method) and it comprised a mathematical modeling. The other one was set with a practical purpose (Practical Method) and comprised the determination of fixed monthly conversion factors. It was used daily Rs data of a 12-years database. With these, there were estimated Rn values by the standard method recommended by FAO. Gauss Method was set using Table Curve 2D 5.01 software. Modeling consisted in defining the values of the equation parameters. On Practical Method we developed monthly coefficients of the ratio Rn/Rs. In order to validate both methods it was measured Rs and Rn during two years using high precision sensors. In addition, Rn values were estimated by both methods and then compared with those measured. Both estimating methods showed satisfactory results, with low error and low advantage for the Gauss Method.
Highlights
In agrometeorology, reference surface consists of a large grass field, which is under full growth, completely shadowing the ground, with approximately 12 cm height, maintained without water and soil fertility restrictions, besides of being free of pests, diseases and weeds (Allen et al, 1998)
This complexity can be attributed to errors in sensor operation, but mainly due to the fact that is relatively normal that weather stations do not receive the well-deserved care to ensure the surface can really be considered a reference surface, as demonstrated by Allen (1996) and Allen et al (2005)
For Dourados City, located in the State of Mato Grosso do Sul, Brazil, both adjusted methods are adequate for estimating Rn from reached surface (Rs) measurements. These authors would like to recommend the use of the Gauss Method, especially in more rigorous applications, where care concerning the estimated value is more pronounced
Summary
Reference surface consists of a large grass field, which is under full growth, completely shadowing the ground, with approximately 12 cm height, maintained without water and soil fertility restrictions, besides of being free of pests, diseases and weeds (Allen et al, 1998). In tropical countries, this theoretical definition is replicated by grass fields cropped with Paspalum notatum Flügge. Examples of mismanagement are: lack of grass field irrigation in arid
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
