Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT
<p>This paper analyzes the differences between ERA-Interim and ERA5 surface winds fields relative to Advanced Scatterometer (ASCAT) ocean vector wind observations, after adjustment for the effects of atmospheric stability and density, using stress-equivalent winds (U10S) and air–sea relative m...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-06-01
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| Series: | Ocean Science |
| Online Access: | https://www.ocean-sci.net/15/831/2019/os-15-831-2019.pdf |
| _version_ | 1818579338501554176 |
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| author | M. Belmonte Rivas M. Belmonte Rivas A. Stoffelen |
| author_facet | M. Belmonte Rivas M. Belmonte Rivas A. Stoffelen |
| author_sort | M. Belmonte Rivas |
| collection | DOAJ |
| description | <p>This paper analyzes the differences between ERA-Interim
and ERA5 surface winds fields relative to Advanced Scatterometer (ASCAT) ocean vector wind
observations, after adjustment for the effects of atmospheric stability and
density, using stress-equivalent winds (U10S) and air–sea relative motion
using ocean current velocities. In terms of instantaneous root mean square (rms) wind speed
agreement, ERA5 winds show a 20 % improvement relative to ERA-Interim
and a performance similar to that of currently operational ECMWF forecasts.
ERA5 also performs better than ERA-Interim in terms of mean and transient wind
errors, wind divergence and wind stress curl biases. Yet, both ERA products
show systematic errors in the partition of the wind kinetic energy into
zonal and meridional, mean and transient components. ERA winds are
characterized by excessive mean zonal winds (westerlies) with too-weak mean
poleward flows in the midlatitudes and too-weak mean meridional winds (trades)
in the tropics. ERA stress curl is too cyclonic in midlatitudes and high latitudes,
with implications for Ekman upwelling estimates, and lacks detail in the
representation of sea surface temperature (SST) gradient effects (along the equatorial cold tongues
and Western Boundary Current (WBC) jets) and mesoscale convective airflows (along the Intertropical Convergence Zone and the warm
flanks for the WBC jets). It is conjectured that large-scale mean wind
biases in ERA are related to their lack of high-frequency (transient wind)
variability, which should be promoting residual meridional circulations in
the Ferrel and Hadley cells.</p> |
| first_indexed | 2024-12-16T07:00:07Z |
| format | Article |
| id | doaj.art-273be03677a449d0903c4e7d8d8a5562 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-12-16T07:00:07Z |
| publishDate | 2019-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-273be03677a449d0903c4e7d8d8a55622022-12-21T22:40:10ZengCopernicus PublicationsOcean Science1812-07841812-07922019-06-011583185210.5194/os-15-831-2019Characterizing ERA-Interim and ERA5 surface wind biases using ASCATM. Belmonte Rivas0M. Belmonte Rivas1A. Stoffelen2Royal Netherlands Meteorology Institute (KNMI), De Bilt, the NetherlandsInstituto de Ciencias del Mar (ICM), Consejo General de Investigaciones Cientificas (CSIC), Barcelona, SpainRoyal Netherlands Meteorology Institute (KNMI), De Bilt, the Netherlands<p>This paper analyzes the differences between ERA-Interim and ERA5 surface winds fields relative to Advanced Scatterometer (ASCAT) ocean vector wind observations, after adjustment for the effects of atmospheric stability and density, using stress-equivalent winds (U10S) and air–sea relative motion using ocean current velocities. In terms of instantaneous root mean square (rms) wind speed agreement, ERA5 winds show a 20 % improvement relative to ERA-Interim and a performance similar to that of currently operational ECMWF forecasts. ERA5 also performs better than ERA-Interim in terms of mean and transient wind errors, wind divergence and wind stress curl biases. Yet, both ERA products show systematic errors in the partition of the wind kinetic energy into zonal and meridional, mean and transient components. ERA winds are characterized by excessive mean zonal winds (westerlies) with too-weak mean poleward flows in the midlatitudes and too-weak mean meridional winds (trades) in the tropics. ERA stress curl is too cyclonic in midlatitudes and high latitudes, with implications for Ekman upwelling estimates, and lacks detail in the representation of sea surface temperature (SST) gradient effects (along the equatorial cold tongues and Western Boundary Current (WBC) jets) and mesoscale convective airflows (along the Intertropical Convergence Zone and the warm flanks for the WBC jets). It is conjectured that large-scale mean wind biases in ERA are related to their lack of high-frequency (transient wind) variability, which should be promoting residual meridional circulations in the Ferrel and Hadley cells.</p>https://www.ocean-sci.net/15/831/2019/os-15-831-2019.pdf |
| spellingShingle | M. Belmonte Rivas M. Belmonte Rivas A. Stoffelen Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT Ocean Science |
| title | Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT |
| title_full | Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT |
| title_fullStr | Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT |
| title_full_unstemmed | Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT |
| title_short | Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT |
| title_sort | characterizing era interim and era5 surface wind biases using ascat |
| url | https://www.ocean-sci.net/15/831/2019/os-15-831-2019.pdf |
| work_keys_str_mv | AT mbelmonterivas characterizingerainterimandera5surfacewindbiasesusingascat AT mbelmonterivas characterizingerainterimandera5surfacewindbiasesusingascat AT astoffelen characterizingerainterimandera5surfacewindbiasesusingascat |