Evaluation of Interannual Simulations and Indian Ocean Dipole Events During 2000–2014 from a Basin Scale General Circulation Model
- 43 Downloads
Interannual simulations performed using an eddy-permitting ocean general circulation model (OGCM) for years 2000–2014 were validated against buoy measurements over the Indian Ocean (IO). Model-simulated fields were evaluated extensively using multiple statistical metrics to quantify the quality of model in reproducing variability in oceanic surface and subsurface features. The model-simulated sea surface temperature (SST) at different moored buoy locations exhibits high (close to + 0.9) correlation coefficient (R) with the ranges of standard deviation (SD) of simulated SST consistent with the corresponding buoy observations. The root mean square difference (RMSD) estimated between the buoy and simulated SST was found to be less than 0.6 °C at most of the buoy locations. The model-simulated subsurface temperature profile, including the thermocline, resembled good agreement with the buoy profiles. Intraseasonal and interannual variability of 20 °C isotherm (D20) was simulated reasonably well as observed at the respective buoy locations. Mean error in surface currents was low; however, the meridional component from model simulations showed a better agreement (RMSD < 0.25 m/s) with the observations as compared to zonal components (< 0.4 m/s) for the periods of buoy data availability. The Dipole Mode Index (DMI) derived from simulated SST reproduces the positive/negative Indian Ocean Dipole (IOD) events that occurred during the simulation period. Interannual variability in temperature, currents and oceanic mixed layer depth was analyzed in response to IOD events. The anomalies in equatorial currents were found to affect the strength of coastal currents along the Indian coastlines. Model simulations showed the enhanced (suppressed) coastal upwelling process along the Sumatra coast that leads to anomalous cooling (warming) off the Sumatra coast during the positive (negative) IOD events.
KeywordsSea surface temperature ROMS model Indian Ocean RAMA buoy interannual variability
RAMA buoy data provided by TAO Project Office of NOAA/PMEL, USA is thankfully acknowledged. Surface current data obtained from Ocean Surface Current Analysis Real-time (OSCAR) through the webpage (http://www.oscar.noaa.gov) managed by OSCAR Project Office, Seattle, WA. Argo data were collected and made freely available by the International Argo Project and the national programs that contribute to it (http://www.argo.ucsd.edu, http://argo.jcommops.org). Argo is a pilot program of the Global Ocean Observing System. The TropFlux data are produced under collaboration between Laboratoired’ Oceanographie Experimentation et Approches Numeriques (LOCEAN) from Institut Pierre Simon Laplace (IPSL, Paris, France) and National Institute of Oceanography/CSIR (NIO, Goa, India). The study benefitted from the funding support under HOOFS program of INCOIS, Hyderabad (ESSO, Ministry of Earth Sciences, Govt. of India). High Performance Computing (HPC) facility provided by IIT Delhi and Department of Science and Technology (DST-FIST, 2014), Govt. of India are thankfully acknowledged. Graphics generated in this manuscript using Ferret and NCL.
- Adler, R.F., Huffman, G.J., Chang, A., Ferraro, R., Xie, P.-P., Janowiak, J., Rudolf, B., Schneider, U., Curtis, S., Bolvin, D., Gruber, A., Susskind, J., Arkin, P., & Nelkin, E. (2003). The version-2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979–present). Journal of Hydrometeorology, 4, 1147–1167. https://doi.org/10.1175/1525-7541(2003)004<1147:tvgpcp>2.0.co;2.Google Scholar
- Arakawa, A., & Lamb, V.R., (1977). Computational design of the basic dynamical processes of the UCLA general circulation model. Methods in Computational Physics, 173–265. https://doi.org/10.1016/b978-0-12-460817-7.50009-4.
- Cox M.D. (1976). Equatorially trapped waves and the generation of the Somali Current. Deep Sea Research and Oceanographic Abstracts, 23(12), 1139–1152. Elsevier.Google Scholar
- David, L. T., & Carrington, D. J. A. (1993). modeling interannual variability in the indian ocean using momentum fluxes from the operational weather analyses of the United Kingdom Meteorological Office and European Centre for Medium Range Weather Forecast. Journal of Geophysical Research, 98, 12483–12499.CrossRefGoogle Scholar
- Haidvogel, D. B., Arango, H., Budgell, W. P., Cornuelle, B. D., Curchitser, E., Di Lorenzo, E., et al. (2008). Ocean forecasting in terrain-following coordinates: Formulation and skill assessment of the Regional Ocean Modeling System. Journal of Computational Physics, 227, 3595–3624. https://doi.org/10.1016/j.jcp.2007.06.016.CrossRefGoogle Scholar
- Haidvogel, D. B., Arango, H. G., Hedstrom, K., Beckmann, A., Malanotte-Rizzoli, P., & Shchepetkin, A. F. (2000). Model evaluation experiments in the North Atlantic Basin: Simulations in nonlinear terrain-following coordinates. Dynamics of atmospheres and oceans, 32, 239–281. https://doi.org/10.1016/S0377-0265(00)00049-X.CrossRefGoogle Scholar
- Huffman, G.J., Adler, R.F., Arkin, P., Chang, A., Ferraro, R., Gruber, A., Janowiak, J., McNab, A., Rudolf, B., & Schneider, U. (1997). The Global Precipitation Climatology Project (GPCP) combined precipitation dataset. Bulletin of the American Meteorological Society, 78, 5–20. https://doi.org/10.1175/1520-0477(1997)078<0005:tgpcpg>2.0.co;2.Google Scholar
- Liu, W.T., Katsaros, K.B., & Businger, J.A. (1979). Bulk parameterization of air-sea exchanges of heat and water vapor including the molecular constraints at the interface Journal of the Atmospheric Sciences. https://doi.org/10.1175/1520-0469(1979)036<1722:bpoase>2.0.co;2.Google Scholar
- McPhaden, M. J., Meyers, G., Ando, K., Masumoto, Y., Murty, V. S. N., Ravichandran, M., et al. (2009). RAMA: The research moored array for African–Asian–Australian monsoon analysis and prediction. Bulletin of the American Meteorological Society, 90, 459–480. https://doi.org/10.1175/2008BAMS2608.1.CrossRefGoogle Scholar
- Phillips, N. A. (1957). A coordinate system having some special advantages for numerical forecasting. Journal of Meteorology. https://doi.org/10.1175/1520-0469(1957)014<0184:acshss>2.0.co;2.Google Scholar
- Praveen Kumar, B., Vialard, J., Lengaigne, M., Murty, V. S. N., McPhaden, M. J., Cronin, M. F., et al. (2013). TropFlux wind stresses over the tropical oceans: Evaluation and comparison with other products. Climate Dynamics, 40, 2049–2071. https://doi.org/10.1007/s00382-012-1455-4.CrossRefGoogle Scholar
- Rao, S. A., Behera, S. K., Masumoto, Y., & Yamagata, T. (2002). Interannual subsurface variability in the tropical Indian Ocean with a special emphasis on the Indian Ocean Dipole. Deep Sea Research Part II: Topical Studies in Oceanography, 49, 1549–1572. https://doi.org/10.1016/S0967-0645(01)00158-8.CrossRefGoogle Scholar
- Rao, K.G, & Goswami, B.N. (1988). Interannual variations of sea surface temperature over the Arabian Sea and the Indian Monsoon: A new perspective. Monthly Weather Review. https://doi.org/10.1175/1520-0493(1988)116<0558:ivosst>2.0.co;2.Google Scholar
- Schiller, A., Godfrey, J.S., McIntosh, P.C., Meyers, G., & Fiedler, R. (2000). Interannual dynamics and thermodynamics of the Indo–Pacific Oceans. Journal of Physical Oceanography, 30, 987–1012. https://doi.org/10.1175/1520-0485(2000)030<0987:idatot>2.0.co;2.Google Scholar
- Schott, F. A., Xie, S. P., & McCreary, J. P., Jr. (2009). Indian Ocean circulation and climate variability. Reviews of Geophysics, 47, 1–46. https://doi.org/10.1029/2007RG000245.1.INTRODUCTION.CrossRefGoogle Scholar
- Shchepetkin, A.F., & McWilliams, J.C. (1998). Quasi-monotone advection schemes based on explicit locally adaptive dissipation. Monthly Weather Review, 126, 1541–1580. https://doi.org/10.1175/1520-0493(1998)126<1541:qmasbo>2.0.co;2.Google Scholar
- Shchepetkin, A.F., & McWilliams, J.C. (2003). A method for computing horizontal pressure-gradient force in an oceanic model with a nonaligned vertical coordinate. Journal of Geophysical Research: Oceans, 108, 3090. https://doi.org/10.1029/2001jc001047.
- Tourre, Y.M., & White, W.B. (1995). ENSO Signals in Global Upper-Ocean Temperature. Journal of Physical Oceanography. https://doi.org/10.1175/1520-0485(1995)025<1317:esiguo>2.0.co;2.Google Scholar
- Vinayachandran, P.N., Francis, P.A., & Suryachandra Rao, A. (2009). Indian Ocean dipole: Processes and impacts. Current Trends in Science, 569–589.Google Scholar
- Vinayachandran, P.N., & Shetye, S.R. (1991). The warm pool in the Indian Ocean. Proceedings of the Indian Academy of Sciences-Earth and Planetary Sciences, 100(2), 165–175.Google Scholar