Posters

Abstract

Currently, the reanalysis has become the de-facto tool to assess climate trends. In the wind industry we are concerned with how the wind patterns change on a climate timescale#_msocom_1. As climatologists we turn to the reanalysis for answers. However, the wind industry faces an auto-imposed barrier other climatologist don't, which I call the Y2k-bug. As with many rumours or legends, the origin is not clear to many, but for many years now there's a popular dogma that proclaims that reanalysis surface wind speed all over the world are not "consistent" before and after the year 2000. Therefore, we should limit wind resource long-term assessment datasets to the period 2000-onwards. If we assume that the main source of variability in the annual mean wind speed over a site is the internal decadal variability instead of the climatic trend, naturally, to get a better understanding of the long-term wind resource over a site, we have to look at climate timescales (50 years or more), but because of the Y2k-bug, it is discouraged. In the presentation I will explain the reanalysis data assimilation process, the new types of observations that were introduced around the year 2000 for reanalysis assimilation, and studies that look at the influence of individual observation types on the final reanalysis.