Energetics of interannual temperature variability
Energetics of interannual temperature variability in the years 1980–2016 is studied using two reanalysis data sets. Monthly temperature anomalies are decomposed to contributions from the net surface energy flux, atmospheric energy convergence minus storage (CONV), and processes that affect the top-of-the-atmosphere radiation balance. The analysis reveals a strong compensation between the net surface heat flux and CONV over the ice-free oceans, with the former driving the temperature variability over the tropical oceans and the latter at higher latitudes. CONV also makes a dominant contribution to temperature anomalies in the winter hemisphere extratopical continents. During the summer half-year and in the tropics, however, variations in cloudiness dominate the temperature variability over land, while the contribution of CONV is modest or even negative. The latter reflects the diffusion-like behaviour of short-term atmospheric variability, which acts to spread out the local, to a large extent cloud-induced temperature anomalies to larger areas. The ERA-Interim and MERRA2 reanalyses largely agree on the general energy budget features of interannual temperature variability, although substantial quantitative differences occur in some of the individual terms.
KeywordsTemperature variability Energy budget Reanalysis ERA-Interim MERRA2
The author thanks the three reviewers for their constructive comments. This work was supported by the Academy of Finland Centre of Excellence in Atmospheric Science—From Molecular and Biological processes to the Global Climate (Luonnontieteiden ja Tekniikan Tutkimuksen Toimikunta, project 307331).
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