Korean Journal of Remote Sensing, Vol.28, No.5, 2012, pp.521~529 http://dx.doi.org/10.7780/kjrs.2012.28.5.5 Spatial Estimation of Priestley-Taylor Based Potential Evapotranspiration Using MODIS Imageries: the Nak-dong river basin Chanyang Sur*, Jongjin Lee**, Jaeyoung Park** and Minha Choi* *Department of Civil engineering, Hanyang University, **Water Resources Investigation and Planning Department, K-water Abstract : The evapotranspiration (ET) is one of the most important factor in the hydrological cycle. In this study, remote sensing based ET algorithm using Moderate Resolution Imaging Spectroradiometer (MODIS) was considered. Then, Priestley-Taylor algorithm was used for estimation of potential evapotranspiration in South Korea, and its spatial distribution was analyzed. Overall applicability between estimated potential evapotranspiration and weather station pan evaporation in Nakdong river basin was represented. The results using small pan showed that correlation coefficient in Pohang and Moonkyung Station was 0.70 and 0.55, respectively. However, the results using large pan showed correlation coefficient in Pohang and Moonkyung Station was 0.62 and 0.52, respectively. Key Words : Potential Evapotranspiration, Pan Evaporation, MODIS, Priestley-Taylor algorithm, Remote Sensing 521
Korean Journal of Remote Sensing, Vol.28, No.5, 2012 522
Spatial Estimation of Priestley-Taylor Based Potential Evapotranspiration Using MODIS Imageries: the Nak-dong river basin Fig. 1. The measurement status of evapotranspiration at Nakdong river. ET o = a D (R _ N G) (1) D + g D kp a C g kp a C _1 R N Mjm _ 2 day _1 Mjm _ 2 day _1 a a 523
Korean Journal of Remote Sensing, Vol.28, No.5, 2012 Fig. 2. Sinusoidal model (Bisht et al., 2005). 524
Spatial Estimation of Priestley-Taylor Based Potential Evapotranspiration Using MODIS Imageries: the Nak-dong river basin 2010. 01 2010. 02 2010. 03 2010. 04 2010. 05 2010. 06 Fig. 3. Spatial distribution of Priestley-Taylor based potential evapotranspiration. 525
Korean Journal of Remote Sensing, Vol.28, No.5, 2012 2010. 07 2010. 08 2010. 09 2010. 10 Fig. 3. Continued 2010. 11 2010. 12 526
Spatial Estimation of Priestley-Taylor Based Potential Evapotranspiration Using MODIS Imageries: the Nak-dong river basin Small pan Large pan Fig. 4. Validation between MODIS based PET and Evaporation Pan at Pohang Weather Station. Small pan Large pan Fig. 5. Validation between MODIS based PET and Evaporation Pan at Moonkyung Weather Station. Table 1. Statistics comparing pan evaporation and Priestley- Taylor based PET Evapotranspiration Site R Regression Equation Small Pan 0.70 y = 0.71 x + 1.86 Pohang Large Pan 0.55 y = 0.50 x + 4.44 Moonkyung Small Pan 0.62 y = 0.60 x + 2.24 Large pan 0.52 y = 0.70 x + 4.21 a a 527
Korean Journal of Remote Sensing, Vol.28, No.5, 2012 Allen, R.G., L.S. Percira, D. Raes, and M. Smith, 528
Spatial Estimation of Priestley-Taylor Based Potential Evapotranspiration Using MODIS Imageries: the Nak-dong river basin 1998. Crop evapotranspiration: guidelines for computing crop requirements. Irrigation and Drainage Paper 56. United Nations-Food and Agricultural Organization (FAO), Rome, Italy. Bisht, G., V. Venturini, S. Islam, and L. Jiang, 2005. Estimation of the net radiation using MODIS (Moderate Resolution Imaging Spectroradiometer) data for clear sky days, Remote Sensing of Environment, 97: 52-67. Chattopadhyay, N. and M. Hulme, 1997. Evaporation and potential evapotranspiration in India under conditions of recent and future climate change, Agricultural and Forest Meteorology, 87: 55-73. Douglas, M.E., M.J. Jacobs, M.D. Summer, and L.R. Ray, 2009. A comparison of models for estimating potential evapotranspiration for Florida land cover types, Journal of Hydrology, 373: 366-376. Ferguson, H.L. and G.H. Den, 2009. Meteorological studies of evaporation at Perch lake, Ontario. Hydrological studies on a small basin on the Canadian shield-evaporation studies, P.J. Barry, Ed.AECL Chalk River Nuclear Laboratories, 417-448. Flint, A.L. and S.W. Childs, 1991. Use of the Priestley-Taylor evaporation equation for soil water limited conditions in a small forest clearcut. Agricultural and Forest Meteorology, 56: 247-260. Irmak, S. and D.Z. Haman, 2003. Evaluation of five methods for estimating class A pan evaporation in a humid climate. Hort Technology, 13: 500-508. Kim, J. and T.S. Hogue, 2007. Evaluation of a MODIS-Based Potential Evapotranspiration Product at the Point Scale. Journal of Hydrometeorology, 9: 444-460. Lagouarde, J.P. and Y. Brunet, 1983. A simple model for estimating the daily upward longwave surface radiation flux from NOAA-AVHRR data, 14: 907-925. Mukammal, E.I. and H.H. Neumann, 1977. Application of the Priestly-Taylor evaporation model to assess the influence of soil moisture on the evaporation from a large weighing lysimeter and class A pan, Boundry-Layer Meteorology, 14: 243-256. Penman, H.L., 1948. Natural evaporation from open water, bare soil, and grass, Proceeding of the Royal Society London, A193: 120-146. Priestley, C.H.B. and R.J. Taylor, 1972. On the assessment of surface heat flux and evaporation using large-scale parameters, Monthly Weather Review, 81-92. Showmaker, W.B. and M.D. Sumner, 2006. Laternate corrections for estimating actual wetland evapotranspiration from potential evapotranspiration, Wetlands, 26: 528-543. Stewart, R.B. and W.R. Rouse, 1976. A simple method for determining the evaporation from shallow lakes and ponds, Water Resources Research, 12: 623-628. Stewart, R.B. and W.R. Rouse, 1977. Substantiation of the Priestley-Taylor parameters =1.26 for potential evaporation in high latitudes, Journal of Applied Meteorology, 16: 623-650. 529