Upscaling impact of wind/sea surface temperature mesoscale interactions on southern Africa austral summer climate

Fabien Desbiolles; Ross Blamey; Serena Illig; Rachel James; Rondrotiana Barimalala; Lionel Renault; Chris Reason

doi:10.1002/joc.5726

Upscaling impact of wind/sea surface temperature mesoscale interactions on southern Africa austral summer climate

Fabien Desbiolles^*, Ross Blamey, Serena Illig, Rachel James, Rondrotiana Barimalala, Lionel Renault, Chris Reason

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

15 Citations (Scopus)

Abstract

Mesoscale sea surface temperature (SST) variability plays an important role in shaping local atmospheric boundary layers through thermodynamic processes. This study focuses on the upscaling effects of mesoscale SST gradients in sensitive areas on the southern Africa regional atmospheric circulation. Using regional atmospheric model sensitivity experiments which differ only in the mesoscale SST forcing characteristics (either the full spectrum of SST variability or only its large-scale components are included), we first quantify the importance of SST gradients on regional atmospheric conditions. Agulhas eddies and meanders influence the vertical air column up to the troposphere, and mesoscale ocean patterns significantly modify incoming landwards moisture fluxes. The austral summer mean state is then modified in terms of air temperature, cloud cover and mean rainfall, with notable differences in tropical rainbands over southwestern Africa. Mesoscale SST variability favours tropical–extra-tropical interactions and cloudband development over the continent. These results stress the importance of high-resolution ocean forcing for accurate atmospheric simulations.

Original language	English
Pages (from-to)	4651-4660
Number of pages	10
Journal	International Journal of Climatology
Volume	38
Issue number	12
DOIs	https://doi.org/10.1002/joc.5726 https://doi.org/10.1002/joc.5726
Publication status	Published - 5 Aug 2018

Bibliographical note

Funding Information:
information Natural Environment Research Council; NERCThis research was supported by NERC (Natural Environment Research Council), as part of the UMFULA project funded by the FCFA (Future Climate For Africa) program. F.D., R.B., R.J., R.B., and C.J.C.R. are directly linked to the project. Support for this study has also been provided by UCT for F.D., R.B., R.J., R.B., and C.J.C.R., IRD (Institut de Recherche et de Developement) for S.I. and L.R., by the National Research Foundation (NRF) for L.R. Authors thanks Dr. Aude Illig for fruitful discussions on statistics. All data used in this study are freely available by the following ftp or url, namely, OSTIA SST (ftp://podaac-ftp.jpl.nasa.gov/allData/ghrsst/data/L4/GLOB/UKMO/OSTIA/), MUR SST (https://podaac.jpl.nasa.gov/dataset/JPL-L4UHfnd-GLOB-MUR), AVHRR SST (ftp://eclipse.ncdc.noaa.gov/pub/OI-daily-v2/NetCDF/), and QuikSCAT L3 data (ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/MWF/L3/QuikSCAT/Daily/Netcdf/). The model configurations have been developed using facilities provided by ICTS High Performance Computing team at UCT (http://hpc.uct.ac.za) and the CSAG computing facility CORE. The ensemble-simulations have been run on the national UK Cluster ARCHER.

Funding Information:
This research was supported by NERC (Natural Environment Research Council), as part of the UMFULA project funded by the FCFA (Future Climate For Africa) program. F.D., R.B., R.J., R.B., and C.J.C.R. are directly linked to the project. Support for this study has also been provided by UCT for F.D., R.B., R.J., R.B., and C.J.C.R., IRD (Institut de Recherche et de Developement) for S.I. and L.R., by the National Research Foundation (NRF) for L.R. Authors thanks Dr. Aude Illig for fruitful discussions on statistics. All data used in this study are freely available by the following ftp or url, namely, OSTIA SST (ftp://podaac-ftp.jpl.nasa. gov/ allData/ghrsst/data/L4/GLOB/UKMO/OSTIA/), MUR SST (https://podaac.jpl.nasa.gov/dataset/JPL-L4UHfnd-GLOB-MUR), AVHRR SST (ftp://eclipse.ncdc.noaa.gov/ pub/OI-daily-v2/NetCDF/), and QuikSCAT L3 data (ftp:// ftp.ifremer.fr/ifremer/cersat/products/gridded/MWF/L3/Quik SCAT/Daily/Netcdf/). The model configurations have been developed using facilities provided by ICTS High Performance Computing team at UCT (http://hpc.uct.ac.za) and the CSAG computing facility CORE. The ensemble-simulations have been run on the national UK Cluster ARCHER.

Publisher Copyright:
© 2018 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.

Keywords

atmospheric circulation
mesoscale SST forcing
rainfall variability
southern Africa summer climate
upscaling effects of mesoscale air–sea interactions

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@article{ef6c2abfe4784d1dbf22f0d2eb1f584a,

title = "Upscaling impact of wind/sea surface temperature mesoscale interactions on southern Africa austral summer climate",

abstract = "Mesoscale sea surface temperature (SST) variability plays an important role in shaping local atmospheric boundary layers through thermodynamic processes. This study focuses on the upscaling effects of mesoscale SST gradients in sensitive areas on the southern Africa regional atmospheric circulation. Using regional atmospheric model sensitivity experiments which differ only in the mesoscale SST forcing characteristics (either the full spectrum of SST variability or only its large-scale components are included), we first quantify the importance of SST gradients on regional atmospheric conditions. Agulhas eddies and meanders influence the vertical air column up to the troposphere, and mesoscale ocean patterns significantly modify incoming landwards moisture fluxes. The austral summer mean state is then modified in terms of air temperature, cloud cover and mean rainfall, with notable differences in tropical rainbands over southwestern Africa. Mesoscale SST variability favours tropical–extra-tropical interactions and cloudband development over the continent. These results stress the importance of high-resolution ocean forcing for accurate atmospheric simulations.",

keywords = "atmospheric circulation, mesoscale SST forcing, rainfall variability, southern Africa summer climate, upscaling effects of mesoscale air–sea interactions",

author = "Fabien Desbiolles and Ross Blamey and Serena Illig and Rachel James and Rondrotiana Barimalala and Lionel Renault and Chris Reason",

note = "Funding Information: information Natural Environment Research Council; NERCThis research was supported by NERC (Natural Environment Research Council), as part of the UMFULA project funded by the FCFA (Future Climate For Africa) program. F.D., R.B., R.J., R.B., and C.J.C.R. are directly linked to the project. Support for this study has also been provided by UCT for F.D., R.B., R.J., R.B., and C.J.C.R., IRD (Institut de Recherche et de Developement) for S.I. and L.R., by the National Research Foundation (NRF) for L.R. Authors thanks Dr. Aude Illig for fruitful discussions on statistics. All data used in this study are freely available by the following ftp or url, namely, OSTIA SST (ftp://podaac-ftp.jpl.nasa.gov/allData/ghrsst/data/L4/GLOB/UKMO/OSTIA/), MUR SST (https://podaac.jpl.nasa.gov/dataset/JPL-L4UHfnd-GLOB-MUR), AVHRR SST (ftp://eclipse.ncdc.noaa.gov/pub/OI-daily-v2/NetCDF/), and QuikSCAT L3 data (ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/MWF/L3/QuikSCAT/Daily/Netcdf/). The model configurations have been developed using facilities provided by ICTS High Performance Computing team at UCT (http://hpc.uct.ac.za) and the CSAG computing facility CORE. The ensemble-simulations have been run on the national UK Cluster ARCHER. Funding Information: This research was supported by NERC (Natural Environment Research Council), as part of the UMFULA project funded by the FCFA (Future Climate For Africa) program. F.D., R.B., R.J., R.B., and C.J.C.R. are directly linked to the project. Support for this study has also been provided by UCT for F.D., R.B., R.J., R.B., and C.J.C.R., IRD (Institut de Recherche et de Developement) for S.I. and L.R., by the National Research Foundation (NRF) for L.R. Authors thanks Dr. Aude Illig for fruitful discussions on statistics. All data used in this study are freely available by the following ftp or url, namely, OSTIA SST (ftp://podaac-ftp.jpl.nasa. gov/ allData/ghrsst/data/L4/GLOB/UKMO/OSTIA/), MUR SST (https://podaac.jpl.nasa.gov/dataset/JPL-L4UHfnd-GLOB-MUR), AVHRR SST (ftp://eclipse.ncdc.noaa.gov/ pub/OI-daily-v2/NetCDF/), and QuikSCAT L3 data (ftp:// ftp.ifremer.fr/ifremer/cersat/products/gridded/MWF/L3/Quik SCAT/Daily/Netcdf/). The model configurations have been developed using facilities provided by ICTS High Performance Computing team at UCT (http://hpc.uct.ac.za) and the CSAG computing facility CORE. The ensemble-simulations have been run on the national UK Cluster ARCHER. Publisher Copyright: {\textcopyright} 2018 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.",

year = "2018",

month = aug,

day = "5",

doi = "10.1002/joc.5726",

language = "English",

volume = "38",

pages = "4651--4660",

journal = "International Journal of Climatology",

issn = "0899-8418",

publisher = "Wiley",

number = "12",

}

TY - JOUR

T1 - Upscaling impact of wind/sea surface temperature mesoscale interactions on southern Africa austral summer climate

AU - Desbiolles, Fabien

AU - Blamey, Ross

AU - Illig, Serena

AU - James, Rachel

AU - Barimalala, Rondrotiana

AU - Renault, Lionel

AU - Reason, Chris

N1 - Funding Information: information Natural Environment Research Council; NERCThis research was supported by NERC (Natural Environment Research Council), as part of the UMFULA project funded by the FCFA (Future Climate For Africa) program. F.D., R.B., R.J., R.B., and C.J.C.R. are directly linked to the project. Support for this study has also been provided by UCT for F.D., R.B., R.J., R.B., and C.J.C.R., IRD (Institut de Recherche et de Developement) for S.I. and L.R., by the National Research Foundation (NRF) for L.R. Authors thanks Dr. Aude Illig for fruitful discussions on statistics. All data used in this study are freely available by the following ftp or url, namely, OSTIA SST (ftp://podaac-ftp.jpl.nasa.gov/allData/ghrsst/data/L4/GLOB/UKMO/OSTIA/), MUR SST (https://podaac.jpl.nasa.gov/dataset/JPL-L4UHfnd-GLOB-MUR), AVHRR SST (ftp://eclipse.ncdc.noaa.gov/pub/OI-daily-v2/NetCDF/), and QuikSCAT L3 data (ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/MWF/L3/QuikSCAT/Daily/Netcdf/). The model configurations have been developed using facilities provided by ICTS High Performance Computing team at UCT (http://hpc.uct.ac.za) and the CSAG computing facility CORE. The ensemble-simulations have been run on the national UK Cluster ARCHER. Funding Information: This research was supported by NERC (Natural Environment Research Council), as part of the UMFULA project funded by the FCFA (Future Climate For Africa) program. F.D., R.B., R.J., R.B., and C.J.C.R. are directly linked to the project. Support for this study has also been provided by UCT for F.D., R.B., R.J., R.B., and C.J.C.R., IRD (Institut de Recherche et de Developement) for S.I. and L.R., by the National Research Foundation (NRF) for L.R. Authors thanks Dr. Aude Illig for fruitful discussions on statistics. All data used in this study are freely available by the following ftp or url, namely, OSTIA SST (ftp://podaac-ftp.jpl.nasa. gov/ allData/ghrsst/data/L4/GLOB/UKMO/OSTIA/), MUR SST (https://podaac.jpl.nasa.gov/dataset/JPL-L4UHfnd-GLOB-MUR), AVHRR SST (ftp://eclipse.ncdc.noaa.gov/ pub/OI-daily-v2/NetCDF/), and QuikSCAT L3 data (ftp:// ftp.ifremer.fr/ifremer/cersat/products/gridded/MWF/L3/Quik SCAT/Daily/Netcdf/). The model configurations have been developed using facilities provided by ICTS High Performance Computing team at UCT (http://hpc.uct.ac.za) and the CSAG computing facility CORE. The ensemble-simulations have been run on the national UK Cluster ARCHER. Publisher Copyright: © 2018 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.

PY - 2018/8/5

Y1 - 2018/8/5

N2 - Mesoscale sea surface temperature (SST) variability plays an important role in shaping local atmospheric boundary layers through thermodynamic processes. This study focuses on the upscaling effects of mesoscale SST gradients in sensitive areas on the southern Africa regional atmospheric circulation. Using regional atmospheric model sensitivity experiments which differ only in the mesoscale SST forcing characteristics (either the full spectrum of SST variability or only its large-scale components are included), we first quantify the importance of SST gradients on regional atmospheric conditions. Agulhas eddies and meanders influence the vertical air column up to the troposphere, and mesoscale ocean patterns significantly modify incoming landwards moisture fluxes. The austral summer mean state is then modified in terms of air temperature, cloud cover and mean rainfall, with notable differences in tropical rainbands over southwestern Africa. Mesoscale SST variability favours tropical–extra-tropical interactions and cloudband development over the continent. These results stress the importance of high-resolution ocean forcing for accurate atmospheric simulations.

AB - Mesoscale sea surface temperature (SST) variability plays an important role in shaping local atmospheric boundary layers through thermodynamic processes. This study focuses on the upscaling effects of mesoscale SST gradients in sensitive areas on the southern Africa regional atmospheric circulation. Using regional atmospheric model sensitivity experiments which differ only in the mesoscale SST forcing characteristics (either the full spectrum of SST variability or only its large-scale components are included), we first quantify the importance of SST gradients on regional atmospheric conditions. Agulhas eddies and meanders influence the vertical air column up to the troposphere, and mesoscale ocean patterns significantly modify incoming landwards moisture fluxes. The austral summer mean state is then modified in terms of air temperature, cloud cover and mean rainfall, with notable differences in tropical rainbands over southwestern Africa. Mesoscale SST variability favours tropical–extra-tropical interactions and cloudband development over the continent. These results stress the importance of high-resolution ocean forcing for accurate atmospheric simulations.

KW - atmospheric circulation

KW - mesoscale SST forcing

KW - rainfall variability

KW - southern Africa summer climate

KW - upscaling effects of mesoscale air–sea interactions

UR - http://dx.doi.org/10.1002/joc.5726

U2 - 10.1002/joc.5726

DO - 10.1002/joc.5726

M3 - Article (Academic Journal)

VL - 38

SP - 4651

EP - 4660

JO - International Journal of Climatology

JF - International Journal of Climatology

SN - 0899-8418

IS - 12

ER -

Upscaling impact of wind/sea surface temperature mesoscale interactions on southern Africa austral summer climate

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