TY - JOUR
T1 - Uncertainties in ocean latent heat flux variations over recent decades in satellite-based estimates and reduced observation reanalyses
AU - Robertson, Franklin R.
AU - Roberts, Jason B.
AU - Bosilovich, Michael G.
AU - Bentamy, Abderrahim
AU - Clayson, Carol Anne
AU - Fennig, Karsten
AU - Schröder, Marc
AU - Tomita, Hiroyuki
AU - Compo, Gilbert P.
AU - Gutenstein, M.
AU - Hersbach, Hans
AU - Kobayashi, Chiaki
AU - Ricciardulli, Lucrezia
AU - Sardeshmukh, Prashant
AU - Slivinski, Laura C.
N1 - Funding Information:
Acknowledgments. FRR, JBR, and MGB acknowledge support for this investigation through the NASA Energy and Water Cycle Study (NEWS), Dr. Jared Entin, Program Manager. MS acknowledges the financial support by the EUMETSAT member states through CM SAF. The NOAA-CIRES-DOE Twentieth Century Reanalysis Project version 3 used resources of the National Energy Research Scientific Computing Center managed by Lawrence Berkeley National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC02-05CH11231 and used resources of NOAA’s remotely deployed high-performance computing systems. Support for the Twentieth Century Reanalysis Project version 3 dataset is provided by the U.S. DOE, Office of Science Biological and Environmental Research (BER), by the NOAA Climate Program Office, and by the NOAA Physical Sciences Laboratory. RSS products are supported by funding from the NASA Earth Science Division. H. Tomita acknowledges support from JSPS Grants JP18H03726, JP18H03737, and JP19H05696 and JAXA Announcement EO-2. We gratefully acknowledge provision and institutional support for the following SST datasets: ESA CCI (http://data.ceda.ac.uk/ neodc/esacci/sst/data/CDR_v2/); NOAA Optimum Interpolation 1/4 Degree Daily Sea Surface Temperature (OISST) Analysis, version 2, (https:/doi.org/10.7289/ V5SQ8XB5); NOAA ERSST v5 (https:/doi.org/10.7289/ V5T72FNM) and access to COBE-SST2 provided by the NOAA/OAR/ESRL PSD ([email protected]); 20CRv3 data are available at the NERSC Science Tape Gateway via portal.nersc.gov. The authors also thank two anonymous reviewers whose comments improved an earlier version of this paper.
Publisher Copyright:
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PY - 2020/10/1
Y1 - 2020/10/1
N2 - Four state-of-the-art satellite-based estimates of ocean surface latent heat fluxes (LHFs) extending over three decades are analyzed, focusing on the interannual variability and trends of near-global averages and regional patterns. Detailed intercomparisons are made with other datasets including 1) reduced observation reanalyses (RedObs) whose exclusion of satellite data renders them an important independent diagnostic tool; 2) a moisture budget residual LHF estimate using reanalysis moisture transport, atmospheric storage, and satellite precipitation; 3) the ECMWF Reanalysis 5 (ERA5); 4) Remote Sensing Systems (RSS) single-sensor passive microwave and scatterometer wind speed retrievals; and 5) several sea surface temperature (SST) datasets. Large disparities remain in near-global satellite LHF trends and their regional expression over the 1990–2010 period, during which time the interdecadal Pacific oscillation changed sign. The budget residual diagnostics support the smaller RedObs LHF trends. The satellites, ERA5, and RedObs are reasonably consistent in identifying contributions by the 10-m wind speed variations to the LHF trend patterns. However, contributions by the near-surface vertical humidity gradient from satellites and ERA5 trend upward in time with respect to the RedObs ensemble and show less agreement in trend patterns. Problems with wind speed retrievals from Special Sensor Microwave Imager/Sounder satellite sensors, excessive upward trends in trends in Optimal Interpolation Sea Surface Temperature (OISST AVHRR-Only) data used in most satellite LHF estimates, and uncertainties associated with poor satellite coverage before the mid-1990s are noted. Possibly erroneous trends are also identified in ERA5 LHF associated with the onset of scatterometer wind data assimilation in the early 1990s.
AB - Four state-of-the-art satellite-based estimates of ocean surface latent heat fluxes (LHFs) extending over three decades are analyzed, focusing on the interannual variability and trends of near-global averages and regional patterns. Detailed intercomparisons are made with other datasets including 1) reduced observation reanalyses (RedObs) whose exclusion of satellite data renders them an important independent diagnostic tool; 2) a moisture budget residual LHF estimate using reanalysis moisture transport, atmospheric storage, and satellite precipitation; 3) the ECMWF Reanalysis 5 (ERA5); 4) Remote Sensing Systems (RSS) single-sensor passive microwave and scatterometer wind speed retrievals; and 5) several sea surface temperature (SST) datasets. Large disparities remain in near-global satellite LHF trends and their regional expression over the 1990–2010 period, during which time the interdecadal Pacific oscillation changed sign. The budget residual diagnostics support the smaller RedObs LHF trends. The satellites, ERA5, and RedObs are reasonably consistent in identifying contributions by the 10-m wind speed variations to the LHF trend patterns. However, contributions by the near-surface vertical humidity gradient from satellites and ERA5 trend upward in time with respect to the RedObs ensemble and show less agreement in trend patterns. Problems with wind speed retrievals from Special Sensor Microwave Imager/Sounder satellite sensors, excessive upward trends in trends in Optimal Interpolation Sea Surface Temperature (OISST AVHRR-Only) data used in most satellite LHF estimates, and uncertainties associated with poor satellite coverage before the mid-1990s are noted. Possibly erroneous trends are also identified in ERA5 LHF associated with the onset of scatterometer wind data assimilation in the early 1990s.
KW - ITC-CV
KW - n/a OA procedure
U2 - 10.1175/JCLI-D-19-0954.1
DO - 10.1175/JCLI-D-19-0954.1
M3 - Article
AN - SCOPUS:85095792985
SN - 0894-8755
VL - 33
SP - 8415
EP - 8437
JO - Journal of climate
JF - Journal of climate
IS - 19
ER -