Ural blocking event analysis by Dai

The code here are used to analysis Ural blocking events. You should use daily geopotential height at the layer of 500 hPa. This method mainly followed the approaches of Tibaldi and Molteni (1990) and Davini et al. (2012).1. Tibaldi, S., & Molteni, F. On the operational predictability of blocking. Tellus 42A, 343-365 (1990).2. Davini, P., Cagnazzo, C., Gualdi, S., & Navarra, A. Bidimensional diagnostics, variability, and trends of Northern Hemisphere blocking. Journal of Climate 25, 6496-6509 (2012).