EGU2020-7499
https://doi.org/10.5194/egusphere-egu2020-7499
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Temporal variability of inferred surface energy fluxes derived from the ERA5 energy budget

Johannes Mayer1, Michael Mayer1,2, and Leopold Haimberger1
Johannes Mayer et al.
  • 1Department of Meteorology and Geophysics, University of Vienna, Vienna, Austria (johannes.mayer@univie.ac.at)
  • 2European Centre for Medium-Range Weather Forecasts, Reading, United Kingdom

We use the new Copernicus ERA5 reanalysis dataset to evaluate the global atmospheric energy budget using a consistent diagnostic framework and  improved numerical methods. A main outcome of this work are mass consistent divergences of moist static plus kinetic energy fluxes. These divergences are combined with top-of-the-atmosphere fluxes based on satellite observations and reconstructions back to 1985 to obtain net surface energy fluxes (FS) with unprecedented accuracy. The global mean of these FS fields is unbiased by construction. Hence, this product is well-suited for climate studies and model evaluations.  Here, the temporal variability and stability of inferred FS, the land-ocean energy transport and the corresponding water cycle are presented and compared with previous evaluations, which used ERA-Interim. 

The inferred FS fields exhibit a much smaller noise level, and sampling errors are drastically reduced due to the high temporal resolution (hourly) of the ERA5 dataset. Energy budget residuals over land are on the order of 17.0 Wm-2, which represents a 63 % reduction compared to ERA-Interim. We also present time series of FS averaged over the global ocean. Its global mean is 2.0 Wm-2, which is in much better agreement with ocean heat uptake than widely used satellite-derived surface flux products. Moreover, it exhibits reasonable temporal stability at least from 2000 onwards. We compare the annual cycles of FS over the ocean and ocean heat content variations derived from ocean reanalysis products and find good agreement. Overall, our results demonstrate clear improvements over earlier evaluations, but more work is needed to optimally use the available data and further reduce uncertainties.

How to cite: Mayer, J., Mayer, M., and Haimberger, L.: Temporal variability of inferred surface energy fluxes derived from the ERA5 energy budget , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7499, https://doi.org/10.5194/egusphere-egu2020-7499, 2020

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Presentation version 2 – uploaded on 06 May 2020
interchanged slide 4 and 5
  • AC1: Comment on EGU2020-7499, Leopold Haimberger, 06 May 2020

    Nice to have precipitation in the moisture transport slide. Why does precipitation in ERA5 go down?

    • AC2: Reply to AC1, Johannes Mayer, 06 May 2020

      The sudden drop around 2000 can be seen in multiple fields. This may be caused by the model/assimilation and is probably not a real signal.

Presentation version 1 – uploaded on 05 May 2020 , no comments