Abstract
We show evidence that tropical atmospheric variability over the central tropical Pacific modulates the circulation over the western Arctic and the North Atlantic-European sector, impacting the summer precipitation especially over Nordic European countries (NEC). Our results, based on the ERA5 reanalysis, suggest the occurrence of a teleconnection mechanism (similar to the Pacific North American pattern) between the tropical Pacific in early spring and summer precipitation over NEC, and we propose two indices as predictors for NEC summer precipitation based on geopotential height anomalies at 500 hPa over the western tropical Pacific during March. We propose an empirical model based on both indices as predictors and assess the model’s skill with a leave-one-out cross-validation procedure. Over large portions of NEC, our proposed empirical model is able to reproduce dry, normal and wet years, defined from summer standardized precipitation anomalies, with a Heidke skill score greater than 0.9.
Disclosure statement
No potential conflict of interest was reported by the authors.
Acknowledgements
All data we used for this paper is shared through the different centres (GLORYS: http://marine.copernicus.eu/services-portfolio/access-to-products/, [email protected], ERA5: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-pressure-levels-monthly-means?tab=overview, EOBS: https://www.ecad.eu/download/ensembles/download.php#datafiles). We acknowledge the E-OBS dataset from the EU-FP6 project UERRA (http://www.uerra.eu) and the Copernicus Climate Change Service, and the data providers in the ECA&D project (https://www.ecad.eu).