Spatiotemporal characteristics of the vertical structure of predictability over the Northern Hemisphere

Based on nonlinear prediction and NCEP/NCAR monthly multi-level geopotential heights, spatial heterogeneity of predictability was obtained over the Northern Hemisphere. On the whole, the predictability is high in continental and higher levels and low in oceans and lower levels from seasonal to interannual timescale. The predictability of the seasonal time scale is similar with the seasonal to interannual timescale. When it goes to the interannual time scale, the predictability becomes high in lower troposphere and low in mid-upper troposphere contrary to the formers. And on the whole the interannual trend is more predictable than the seasonal trend. The strength of the seasonal cycle plays a great role in the heterogeneity of predictability which is proved true by spectrum analysis. Other reasons maybe the properties of the atmospheric air, topographic forcing and timescale interactions.