1. Allen, R. G., Pereira, L. S., Raes, D., and Smith, M.: Crop evapotranspiration: Guidelines for computing crop water requirements, FAO Irrigation and drainage paper 56, Food and Agriculture Organization of the United Nations, Rome, Italy, available at: http://www.fao.org/docrep/X0490E/X0490E00.htm, 1998.
2. Alley, W. M.: The Palmer Drought Severity Index – Limitations and Assumptions, J. Clim. Appl. Meteorol., 23, 1100–1109, https://doi.org/10.1175/1520-0450(1984)0232.0.CO;2, 1984.
3. American Meteorological Society: Drought: An Information Statement of the American Meteorological Society, American Meteorological Society, Boston, USA, 5 pp., 2013.
4. Anderson, M. C., Norman, J. M., Mecikalski, J. R., Otkin, J. A., and Kustas, W. P.: A climatological study of evapotranspiration and moisture stress across the continental United States based on thermal remote sensing: 2. Surface moisture climatology, J. Geophys. Res.-Atmos., 112, D10117, https://doi.org/10.1029/2006jd007507, 2007a.
5. Anderson, M. C., Norman, J. M., Mecikalski, J. R., Otkin, J. A., and Kustas, W. P.: A climatological study of evapotranspiration and moisture stress across the continental United States based on thermal remote sensing: 1. Model formulation, J. Geophys. Res.-Atmos., 112, D11112, https://doi.org/10.1029/2006jd007506, 2007b.