In GOES-PRWEB, an energy balance approach, similar to Yunhao et al. (2001), is used to estimate actual evapotranspiration, which is then incorporated into a water balance calculation. Solar radiation is derived from a physical model for estimating incident solar radiation at the surface from GOES satellite data, first proposed by Gautier et al. (1980) (see also Diak et al. 1996; Okin et al. 2005; and Sumner et al., 2008). The ground level, 1-km resolution solar radiation product became available in Puerto Rico in March of 2009. Twenty four-hour rainfall is obtained from NOAA’s Advanced Hydrologic Prediction Service (AHPS) website (http://water.weather.gov/precip/). In Puerto Rico, the source of the AHPS rainfall is NEXRAD radar and rain gauge data. Runoff is estimated using the Curve Number method of the USDA Natural Resource Conservation Service (U.S. SCS, 1973, Fangmeier et al., 2005). Eight 3-hour values of wind speed for Puerto Rico, obtained from the National Weather Service’s National Digital Forecast Database (NDFD, 2010), are averaged to obtain the daily average 10-m wind speed (u), and are then adjusted to the “virtual instrument height”, depending on the height of the vegetation. Although the wind speed is a model forecast, it is the best source of spatially distributed wind speed over the island. Minimum, average, maximum and dew point air temperatures are obtained from a lapse rate approach calibrated for Puerto Rico by Goyal et al. (1988) with regression equations relating average air temperature with surface elevation. These temperatures are adjusted daily with a nudging technique, using forecast temperature data from the NDFD. A detailed description of the methodology used in GOES-PRWEB (coded in MatLab) is presented by Harmsen et al. (2009 and 2010).
Results from GOES-PRWEB are available at the following links:
GOES-PRWEB daily images
GOES-PRWEB monthly averages and totals images
GOES-PRWEB annual averages and totals images
Frequently Asked Questions about GOES-PRWEB (for example, “How does it calculate….”)
DISCLAIMER: The information is provided “as is”. The authors and publishers of this information disclaim any loss or liability, either directly or indirectly as a consequence of applying the information provided herein, or in regard to the use and application of said information. No guarantee is given, either expressed or implied, in regard to the accuracy, or acceptability of the information.
Diak, G. R., W.L. Bland, and J. Mecikalski, 1996: A note on first estimates of surface insolation from GOES-8 visible satellite data. Agric. For. Meteorol., 82, 219-226.
Fangmeier, D. D., W. J. Elliot, S. R. Workman, R. L. Huffman, and G. O. Schwab, 2005. Soil and Water Conservation Engineering, Fifth Edition. pp. 528.
Gautier, C., G. R. Diak, and S. Masse, 1980: A simple physical model to estimate incident solar radiation at the surface from GOES satellite data. J. Appl. Meteor.,19, 1007–1012.
Goyal, M. R., E. A. González, C. Chao de Báez, 1988. Temperature versus elevation relationships for Puerto Rico. J. Agric. UPR 72(3):449-67.
Harmsen, E. W., J. Mecikalski, A. Mercado and P. Tosado Cruz, 2010. Estimating evapotranspiration in the Caribbean Region using satellite remote sensing. Proceedings of the AWRA Summer Specialty Conference, Tropical Hydrology and Sustainable Water Resources in a Changing Climate. San Juan, Puerto Rico. August 30-September 1, 2010.
Harmsen, E. W., J. Mecikalski, M. J. Cardona-Soto, A. Rojas Gonzalez and R. Vasquez, 2009. Estimating daily evapotranspiration in Puerto Rico using satellite remote sensing. WSEAS Transactions on Environment and Development. Vol. 6(5):456-465.
Otkin, A. J., M. C. Anerso, J. R. Mecikalski and G. R. Diak, 2005. Validation of GOES-Based Insolation Estimates Using Data from the U.S. Climate Reference Network. J. of Hydrometeorology, Vol. 6, August:460-475.
Sumner, D. M, C. S. Pathak, J. R. Mecikalski, S. fJ. Paech, Q. Wu, and T. Sangoyomi, 2008. Calibration of GOES-derived Solar Radiation Data Using Network of Surface Measurements in Florida, USA. Proceedings of the ASCE World Environmental and Water Resources Congress 2008 Ahupua’a.
U.S. Soil Conservation Service, 1973. A Method for Estimating Volume and Rate of Runoff in Small Watersheds. SCS-TP-149, Washington, D.C.
Yunhao C., L. Xiaobing and S.Peijun, 2001. Estimation of regional evapotranspiration over Northwest China by using remotely sensed data. Journal of Geophysical Sciences, Vol. 11, No. 2, pp 140-148.