the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Brief communication: Surface energy balance differences over Greenland between ERA5 and ERA-Interim
Christian B. Rodehacke
Gerrit Lohmann
Abstract. We compare the main atmospheric drivers of the melt season over the Greenland Ice Sheet (GrIS) in ERA5 and ERA-Interim (ERAI) in their overlapping period 1979–2018. In summer, ERA5 differs significantly from ERAI, especially in the melt regions: averaged over the lower parts of the GrIS, mean near-surface temperature is 1 K lower, while the mean downward shortwave radiation at the surface is on average 15 Wm−2 higher than in ERAI. Comparison with observational weather station data shows a significant warm bias in ERAI and for ERA5 a significant positive bias in downward shortwave radiation. Consequently, methods that previously estimated the GrIS surface mass balance from the ERAI surface energy balance need to be carefully recalibrated before converting to ERA5 forcing.
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Uta Krebs-Kanzow et al.
Status: final response (author comments only)
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RC1: 'Comment on egusphere-2023-525', Anonymous Referee #1, 07 Apr 2023
Review of
Brief communication: Surface energy balance differences over Greenland between ERA5 and ERA-Interim
by Uta Krebs-Kanzow and others
General
This paper issues a warning that researchers that previously used ERA-Interim to estimate Greenland ice sheet (GrIS) surface energy/mass balance (SEB/SMB) must recalibrate their methods when switching to ERA5. The authors find significant differences in near-surface climate, notably near-surface air temperature, and SEB, notably the flux of incoming solar radiation. The paper is generally well written with clear figures but see my technical comments below. The paper is well-timed, as ERA-Interim will be phased out soon at the expense of ERA5. Unfortunately, no interpretation as to why the differences occur between the two products is provided, making the scientific impact of this study somewhat limited.Major comments
In Figure 1 I assume some of the small-scale features in the marginal ice sheet are associated with the interpolation procedure, in combination with comparing two datasets of different resolutions.Minor and textual comments
l. 9: persistent warming trend -> persistent positive trend
l. 10: "a mean warming of 5.3 K is projected for the 21st century". This is ambiguous. By "mean" do you mean model mean, or the mean over the (remainder of) the century, or end-of-century? Please be precise. Also, consider presenting a number from a more likely scenario.
l. 11: " The associated reduction in Greenland Ice Sheet’s surface mass balance (SMB) leads to more runoff " It is the other way around: the associated increase in runoff leads to a reduction of the GrIS SMB...Again, please be precise, there is already enough confusion about ice sheet mass balance.
l. 13: Consider replacing "Surface mass balance models" with "Surface energy balance models".
l. 16: near-surface temperature -> near-surface air temperature
l. 33: Reanalysis Era-Interim (ERAI) -> ECMWF Reanalysis - Interim (ERA-Interim, henceforth ERAI)
l. 34: Reanalysis v5 (ERA5) -> ECMWF Reanalysis v5 (ERA5)
l. 34: ERA5 runs from January 1940 to the present
l. 37: For clarity and consistency with previous work, consider using T2m rather than T2M
l. 70: Please use higher/lower temperatures rather than warmer/colder temperatures throughout.
l. 75: stronger -> larger
Citation: https://doi.org/10.5194/egusphere-2023-525-RC1 -
RC2: 'Comment on egusphere-2023-525', Anonymous Referee #2, 09 May 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-525/egusphere-2023-525-RC2-supplement.pdf
Uta Krebs-Kanzow et al.
Uta Krebs-Kanzow et al.
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