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Knowledge of the solar radiation flux at the ground surface is valuable for many disciplines. For example, in agriculture, solar radiation is necessary for estimating crop water requirements and for performing irrigation scheduling; and long-term records of solar radiation are essential for evaluating solar as a potential energy source.

Currently in Puerto Rico, there are only ten to fifteen functional solar radiation sensors (pyranometers) accessible to the public. Data from these sensors, though valuable near the sensor, may not be representative of areas several kilometers away, especially in areas like Puerto Rico where cloudiness tends to be highly variable. To overcome this problem, high-resolution (1-km) solar radiation data can be estimated from the National Oceanic and Atmospheric Administration’s (NOAA’s) Geostationary Operational Environmental Satellite (GOES). In March of 2009, a GOES hourly and daily-integrated solar radiation product became available for Puerto Rico. In this study, pyranometers were re-calibrated at several locations in Puerto Rico (Fortuna, University of Puerto Rico -Mayaguez Campus [UPRM] and Guilarte). The re-calibration of the pyranometers yielded daily integrated solar radiation calibration equations with coefficients of determination (R2) of 0.9755, 0.9774 and 0.7202, respectively. Based on the relatively large scatter in the Guilarte data, this sensor was deemed to be too inaccurate to use for calibrating the remote sensing data. Sensors at Fortuna and UPRM were used to calibrate the daily integrated remotely sensed solar radiation data. The calibration equations yielded R2 values of 0.8842 and 0.8300, respectively. The calibration equations are validated using approximately 250 days of solar radiation data from 2010. Example calculations are provided to illustrate the use of the calibration equations.

Knowledge of the solar radiation flux at the ground surface is valuable for many disciplines. For example, in agriculture, solar radiation is necessary for estimating crop water requirements and for performing irrigation scheduling; and long-term records of solar radiation are essential for evaluating solar as a potential energy source.

Currently in Puerto Rico, there are only ten to fifteen functional solar radiation sensors (pyranometers) accessible to the public. Data from these sensors, though valuable near the sensor, may not be representative of areas several kilometers away, especially in areas like Puerto Rico where cloudiness tends to be highly variable. To overcome this problem, high-resolution (1-km) solar radiation data can be estimated from the National Oceanic and Atmospheric Administration’s (NOAA’s) Geostationary Operational Environmental Satellite (GOES). In March of 2009, a GOES hourly and daily-integrated solar radiation product became available for Puerto Rico. In this study, pyranometers were re-calibrated at several locations in Puerto Rico (Fortuna, University of Puerto Rico -Mayaguez Campus [UPRM] and Guilarte). The re-calibration of the pyranometers yielded daily integrated solar radiation calibration equations with coefficients of determination (R2) of 0.9755, 0.9774 and 0.7202, respectively. Based on the relatively large scatter in the Guilarte data, this sensor was deemed to be too inaccurate to use for calibrating the remote sensing data. Sensors at Fortuna and UPRM were used to calibrate the daily integrated remotely sensed solar radiation data. The calibration equations yielded R2 values of 0.8842 and 0.8300, respectively. The calibration equations are validated using approximately 250 days of solar radiation data from 2010. Example calculations are provided to illustrate the use of the calibration equations.

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