A new report by Alexey Karpechko, research professor at Finnish Meteorological Institute, has showed that monthly forecasts in mid and high latitudes would be improved if weather models better predicted variability in the stratosphere and tropical atmosphere.
Tropical weather conditions
The study, named “The tropical influence on sub-seasonal predictability of wintertime stratosphere and stratosphere–troposphere coupling”, has been published in the Quarterly Journal of Royal Meteorological Society.
The results show that perfect knowledge of the tropical weather conditions would improve at least every fifth forecast in mid and high latitudes and that perfect knowledge of the stratosphere would also improve monthly forecasts, especially over the Northern Atlantic and Europe, and especially during periods when the stratospheric polar vortex was weakening.
Teleconnections
Monthly forecasts predict weekly mean weather conditions usually up to three to four weeks ahead. Such long forecasts are made possible by so-called teleconnections, which link local weather to remote regions where weather conditions can be predicted for longer time. During winter, such teleconnections are mostly associated with the tropics and the stratosphere.
The researchers applied a “nudging”-technique, which enabled perfect simulations of the stratosphere and tropical atmosphere, and then analyzed how the teleconnections from these regions improve the forecast quality. The results of the research improve our understanding of how the teleconnections work in the atmosphere, and this knowledge can be used for improving forecast models. The research is based on forecasts by the European Centre for Medium Range Weather Forecasts (ECMWF), reanalysis data for the winter seasons 1999-2019.
In related news, the European Research Council recently awarded competitive ERC Consolidator Grant funding to Riku Järvinen’s space weather research project at the Finnish Meteorological Institute. The grant is for five years and approximately €2m (US$2.15m). Click here to read the full story.