Articles | Volume 16, issue 6
https://doi.org/10.5194/os-16-1545-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-16-1545-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Coastal gradients in False Bay, south of Cape Town: what insights can be gained from mesoscale reanalysis?
Mark R. Jury
CORRESPONDING AUTHOR
Geography Department, University of Zululand, KwaDlangezwa, 3886, South Africa
Physics Department, University of Puerto Rico Mayagüez, PR 00681, USA
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Cited articles
Bang, N. D.: The southern Benguela current region in February, 1966, Part
II. Bathythermography and air-sea interactions, Deep Sea Res., 18, 209–224,
1971.
Blamey, L. K., Howard, J. A. E., Agenbag, J., and Jarre, A.: Regime-shifts
in the southern Benguela shelf and inshore region, Prog. Oceanogr. 106,
80–95, 2012.
Botes, W.: Shallow water current meters comparative study: False Bay, CSIR
Report T/SEA 8803, 14, Stellenbosch, 1988.
Brown, A. C., Davies, B. R., Day, J. A., and Gardiner, A. J. C.: Chemical
pollution loading of False Bay, in: False Bay 21 years
on – an environmental assessment, edited by: Jackson, W. P. U., Proc. Symposium, Trans. R. Soc. S. Afr.,
47, 703–716, 1991.
Brundrit, G.: Global Climate Change and Adaptation: City of Cape Town
sea-level rise risk assessment, Phase 5 Full investigation of alongshore
features, City of Cape Town, 2009.
Chassignet, E. P., Hurlburt, H. E., Metzger, E. J., Smedstad, O. M., Cummings, J. A., Halliwell, G. R., Bleck, R., Baraille, R., Wallcraft, A. J., Lozano, C., Tolman, H. L., Srinivasan, A., Hankin, S., Cornillon, P., Weisberg, R., Barth, A., He, R., Werner, F., and Wilkin, J.: US GODAE: Global ocean prediction with
the Hybrid coordinate ocean model (HYCOM), Oceanography, 22, 64–75, 2009.
Coleman, F.: The development and validation of a hydrodynamic model of False
Bay, MSc thesis, Univ. Stellenbosch, 166 pp, 2019.
Cummings, J. A. and Smedstad, O. M.: Variational data assimilation for the
global ocean, in: Data Assimilation for Atmospheric, Oceanic and Hydrologic
Applications Vol. 2, edited by: Park, S. K. and Xu, L., Springer-Verlag, 303–343,
2013.
Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S. B., Hersbach, H., Hólm, E. V., Isaksen, L., Kållberg, P., Köhler, M., Matricardi, M., McNally, A. P., Monge‐Sanz, B. M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J.-N., and Vitart, F.: The ERA-interim reanalysis: configuration and
performance of the data assimilation system, Q. J. Roy. Meteor. Soc.,
137, 553–597, 2011.
de Vos, M., Rautenbach, C., and Ansorge, I.: The inshore circulation at Fish
Hoek, Department of Oceanography UCT, Internal report, Cape Town, 2014.
Dufois, F. and Rouault, M.: Sea surface temperature in False Bay (South
Africa): towards a better understanding of its seasonal and inter-annual
variability, Cont. Shelf Res., 43, 24–35, 2012.
Engelbrecht, F., Landman, W. A., Engelbrecht, C., Landman, S., Bopape, M.
M., Roux, B., McGregor, J. L., and Thatcher, M.: Multi-scale climate
modelling over Southern Africa using a variable-resolution global model,
Water SA, 37, 647–658, 2011.
Fourie, J. P., Ansorge, I., Backeberg, B., Cawthra, H. C., MacHutchon, M.
R., and van Zyl, F. W.: The influence of wave action on coastal erosion along
Monwabisi Beach, Cape Town, S. Afr. J. Geometrics., 4, 96–109, 2015.
Giljam, R.: The effect of the Cape Flats aquifer on the water quality of
False Bay, MSc Thesis, Univ. Cape Town, 2002.
Griffiths, C., Robinson, T., Lange, L., and Mead, A.: Marine biodiversity in
South Africa – state of knowledge, spatial patterns and threats, PloS One,
5 e123008, https://doi.org/10.1371/journal.pone.0012008, 2010.
Grundlingh, M., Hunter, I., and Potgieter, E.: Bottom currents at the
entrance to False Bay, Cont. Shelf Res., 9, 1029–1048, 1989.
Grundlingh, M. and Largier, J.: Physical oceanography of False Bay: a
Review, Trans. Roy. Soc. S. Afr., 47, 387–400, 1991.
Hughes, P. and Brundrit, G. B.: The vulnerability of the False Bay coast
line to the projected rise in sea level, Trans. Roy. Soc. S. Afr., 47,
519–534, 1991.
Hurlburt, H. E., Brassington, G. B., Drillet, Y., Kamachi, M., Benkiran, M., Bourdallé-Badie, R., Chassignet, E.P., Jacobs, G. A., LeGalloudec, O., Lellouche, J.-M., Metzger, E. J., Oke, P. R., Pugh, T. F., Schiller, A., Smedstad, O. M., Tranchant, B., Tsujino, H., Usui, N., and Wallcraft, A. J.: High resolution global and basin-scale
ocean analyses and forecasts, Oceanography, 22, 110–127, 2009.
Jacobson, M., Hermes, J., Jackson-Veitch, J., and Halo, I.: The influence of
a spatially varying wind field on the circulation and thermal structure of
False Bay during summer: a numerical modelling study, Dept Oceanography, UCT
Internal Report, 2014.
Johnson H. K., Vested, H. J., Hersbach, H., Højstrup, J., and Larsen, S.
E.: The coupling between wind and waves in the WAM Model, J. Atmos. Ocean.
Technol., 16, 1780–1790, 1999.
Joubert, J. R. and van Niekerk, J. L.: South African wave energy resource
data, a case study, Stellenbosch, CRSES Internal Report, Stellenbosch, 2013.
Jury, M. R.: The weather of False Bay, Trans. Roy. Soc. S. Afr., 47,
401–427, 1991.
Jury, M. R. and Reason, C. J.: Extreme subsidence in the Agulhas-Benguela air
mass transition, Bound.-Lay. Meteorol., 46, 35–51, 1989.
Jury, M. R. and Brundrit, G. B.: Temporal organisation of upwelling in the
southern Benguela ecosystem by resonant coastal trapped waves in the ocean
and atmosphere, S. Afr. J. Mar. Sci., 12, 219–224, 1992.
Largier, J. L., Chapman, P., Peterson, W. T., and Swart, V. P.: The Western
Agulhas Bank — circulation, stratification and ecology, S. Afr. J. Mar. Sci. 12, 319–339, 1992.
Lloyd, P., Plaganyi, E. E., Weeks, S. J., Magno-Canto, M., and Plaganyi, G.:
Ocean warming alters species abundance patterns and increases species
diversity in an African subtropical reef-fish community, Fish Oceanogr., 21,
78–94, 2012.
Lutjeharms, J. R. E. and Stockton, P. L.: Aspects of the upwelling regime
between Cape Point and Cape Agulhas South Africa, S. Afr. J. Mar. Sci.,
10, 91–102, 1991.
Mather, A., Garland, G., and Stretch, D.: Southern African sea levels:
corrections, influences and trends, Afr. J. Mar. Sci., 31, 145–156,
2009.
Metzger, E. J., Smedstad, O. M., Thoppil, P. G., Hurlburt, H. E., Cummings, J. A., Wallcraft, A. J., Zamudio, L., Franklin, D. S., Posey, P. G., Phelps, M. W., Hogan, P. J., Bub, F. L., and DeHaan, C. J.: US Navy operational global ocean and Arctic
ice prediction systems, Oceanography, 27, 32–43, 2014.
Metzger, E. J., Helber, R. W., Hogan, P. J., Posey, P. G., Thoppil, P. G.,
Townsend, T. L., Wallcraft, A. J., Smedstad, O. M., Franklin, D. S.,
Zamudio-Lopez, L., and Phelps, M. W.: (HYCOM-NCODA) Global Ocean Forecast
System 3.1 validation testing, NRL/MR/7320-17-9722, 2017.
Nelson, G., Cooper, R. M., and Cruickshank, S.: Time series from a current
meter array near Cape Point, Trans. Roy. Soc. S. Afr., 47, 471–482, 1991.
Nicholson, S. A.: The circulation and thermal structure of False Bay: a
process-oriented numerical modelling and observational study, MSc Thesis.
Dept. Oceanography, Univ. Cape Town, 2011.
Parsons, R. P.: Assessment of the impact of the Cape Flats on surrounding
water bodies, S. Peninsula Municipal Report 074/SPM-1, Somerset West, 2000.
Penven, P., Brundrit, G. B., deVerdiere, C. A., Freon, P., Johnson, A. S., and
Shillington, F. A.: A regional hydrodynamic model of upwelling in the
Southern Benguela, S. Afr. J. Sci., 97, 472–475, 2001.
Pfaff, M. C., Logston, R. C., Raemaekers, S. J. P. N., Hermes, J. C., Blamey, L. K., Cawthra, H. C., Colenbrander, D. R., Crawford, R. J. M., Day, E., duPlessis, N., Elwen, S. H., Fawcett, S. E., Jury, M. R., Karenyi, N., Kerwath, S. E., Kirkman, S. P., Kock, A. A., Krug, M., Lamberth, S. J., Omardien, A., Pitcher, G. C., Rautenbach, C., Robinson, T. B., Rouault, M., Ryan, P. G., Shillington, F. A., Sowman, M., Sparks, C. C., Turpie, J. K., vanNiekerk, L., Waldron, H. N., and Yeld, E. M.: A synthesis of three decades of
socio-ecological change in False Bay South Africa: setting the scene for
multidisciplinary research and management, Elem. Sci. Anth., 7, 32, https://doi.org/10.1525/elementa.367, 2019.
Rautenbach, C.: The influence of a space varying wind field on wind-wave
generation in False Bay South Africa, (preprint) SAMSS conference,
Stellenbosch, 2014.
Reynolds, R. W., Rayner, N. A., Smith, T. M., Stokes, D. C., and Wang, W.:
An improved in situ and satellite SST analysis for climate, J. Climate 15,
1609–1625, 2002.
Rouault, M., Pohl, B., and Penven, P.: Coastal oceanic climate change and
variability from 1982 to 2009 around South Africa, Afr. J. Mar. Sci.,
32, 237–246, 2010.
Roux, G. B. and Toms, G.: Reduction of seawall overtopping at the Strand.
Univ. Stellenbosch, Internal Report, 2013.
Saha, S., Moorthi, S., Pan, H.-L., Wu, X., Wang, J., Nadiga, S., Tripp, P., Kistler, R., Woollen, J., Behringer, D., Liu, H., Stokes, D., Grumbine, R., Gayno, G., Wang, J., Hou, Y.-T., Chuang, H-Y., Juang, H-M., Sela, J., Iredell, M., Treadon, R., Kleist, D., vanDelst, P., Keyser, D., Derber, J., Ek, M., Meng, J., Wei, H., Yang, R., Lord, S., vanDenDool, H., Kumar, A., Wang, W., Long, C., Chelliah, M., Xue, Y., Huang, B., Schemm, J.-K., Ebisuzaki, W., Lin, R., Xie, P.-P., Chen, M., Zhou, S., Higgins, W., Zou, C.-Z., Liu, Q., Chen, Y., Han, Y., Cucurull, L., Reynolds, R. W., Rutledge, G., Goldberg, M.: The NCEP Climate Forecast System version 2, J.
Climate, 27, 2185–2208, 2014.
Schlegel, R. W., Oliver, E. C., Wernberg, T., and Smit, A. J.: Nearshore and
offshore co-occurrence of marine heatwaves and cold-spells, Prog. Oceanogr.,
151, 189–205, 2017.
Schilperoort, D. E., Shillington, F., Hermes, J., and Rautenbach, C.:
Investigation into the capability of the Conformal-Cubic Atmospheric Model
in representing the wind fields and patterns over the Fasle Bay region in
comparison to NCEP/NCAR and observational data, Dept. Oceanography, Univ.
Cape Town, Internal Report, 2013.
Shannon, L. V. (Ed.): South African Ocean Colour and Upwelling Experiment,
Sea Fisheries Research Institute, Cape Town, 270 pp, 1985.
Shannon, L. V. and Field, J. G.: Are fish stocks food-limited in the
Southern Benguela pelagic ecosystem?, Mar. Ecol. Prog. Ser. 22, 7–19, 1985,
https://doi.org/10.3354/meps022007.
Skamarock, W. C., Klemp, J. B.. Dudhia, J., Gill, D. O., Barker, D. M.,
Huang, X., Wang, W., and Powers, J. G.: A description of the Advanced
Research WRF v3, NCAR Tech Note 475 pp, 2008.
Tadross, M. A., Taylor, A., and Johnston, P. A.: Understanding Cape Town's
climate, in: Climate
change at the city scale: impacts, mitigation and adaptation in Cape Town, edited by: Cartwright, A., Oelofse, G., Parnell, S., and Ward, S.,
Routledge, 9–20, 2012.
Taljaard, S.: The origin and distribution of dissolved nutrients in False
Bay. Trans. Royal Soc. S. Afr. 47, 4–5, 1991.
Taljaard, S. van Ballegooyen, R., and Morant, P.: False Bay Water Quality
Review, CSIR Report ENV-SC 86: 2, Stellenbosch, 2000.
Theron, A., Rossouw, M., Barwell, L., Maherry, A., Diedericks, G., and de
Wet, P.: Quantification of risk to coastal areas and development: wave
run-up and erosion, (preprint) Science real and relevant conf., Pretoria,
CSIR Internal Report, 2010.
Theron, A., Rossouw, M., Rautenbach, C., von Saint-Ange, U., Maherry, A., and
August, M.: Determination of inshore wave climate along South African coast:
phase 1 coastal hazard and vulnerability assessment, CSIR Internal Report,
Stellenbosch, 2014a.
Theron, A., Rossouw, M., Rautenbach, C., van Niekerk, L., Luck-Vogel, M.,
and Cilliers, L.: South African coastal vulnerability assessment: phase 2,
Stellenbosch: CSIR internal report, 2014b.
Tolman, H. L.: User manual and system documentation of WAVEWATCH-III version
2.22, NCEP Tech. Note, Washington, 139 pp, 2002.
van Ballegooyen, R.: The dynamics relevant to the modelling of synoptic scale
circulations within False Bay, Trans. Roy. Soc. S. Afr., 47, 419–431, 1991.
Wainman, C. K., Polito, A., and Nelson, G.: Winds and subsurface currents in
the False bay region, South Africa, S. Afr. J. Mar. Sci., 5, 337–346,
1987.
World Ocean Atlas: Temperature/Salinity, NOAA Atlas NESDIS 73/74, (observation density), edited by: Locarnini, R. A., 40 pp., 2013.
Short summary
Mesoscale datasets are used to study coastal gradients in the marine climate and oceanography of False Bay, south of Cape Town. Building on past work, satellite and ocean–atmosphere reanalyses are used to gain new insights into the mean structure, circulation and meteorological features. HYCOM v3 hindcasts represent a coastward reduction of mixing that enhances stratification and productivity in False Bay during summer.
Mesoscale datasets are used to study coastal gradients in the marine climate and oceanography of...