Air pressure reference surfaces at topographic height derived from ERA 40 surface pressure

Mean air pressure at topographic height in the interval 1992-2001. The mean is calculated for the 6-hourly samples. For each sample, pressure at topographic height (taken from ETOPO5) is computed from geopotential heights of the ERA 40data set, which is given with a 2.5 degree spatial resolution. Spatial interpolation is linear between the ERA 40 grid points.

Difference of average pressure in 1992-2001 and 1982-1991. The differences are mean in the 1992 window minus mean in the 1982 window.

Difference of average pressure in 1992-2001 and 1972-1981. The differences are mean in the 1992 window minus mean in the 1972 window.

Difference of average pressure in 1992-2001 and 1962-1971. The differences are mean in the 1992 window minus mean in the 1962 window.