Scientia Marina, Vol 74, No 2 (2010)

Climatology and reconstruction of runoff time series in northwest Iberia: influence in the shelf buoyancy budget off Ría de Vigo

Pablo Otero
Instituto Español de Oceanografía , Spain

Manuel Ruiz-Villarreal
Instituto Español de Oceanografía , Spain

Álvaro Peliz
Instituto de Oceanografía, Fac. Ciências Universidade de Lisboa , Portugal

José Manuel Cabanas
Instituto Español de Oceanografía , Spain


River runoff off northwest Iberia generates a low-density buoyant structure with a strong influence on shelf and coastal circulation. This study estimates the runoff to the shelf of the ten largest rivers in the region based on the furthest downstream gauge records available, and also takes into account the basin area downstream from the station (22% of the basin area for the entire study region). Monthly statistics were computed to obtain mean values for each river to cover the recurrent lack of runoff data in the region. In order to reconstruct gaps in the time series on a daily scale, a method based on the observed discharge of a nearby river basin was used. In addition, the influence of runoff on the shelf was analyzed using monthly CTD data sampled during a 12-year period in the Ría de Vigo and the adjacent shelf. The CTD series shows the existence of a buoyant structure with maximum growth during winter and with large variability of its thermal anomaly. The salinity anomaly correlated significantly with mean winter monthly values of the North Atlantic Oscillation (NAO) index. This atmospheric index integrates both the influence of precipitation —and therefore runoff— and the predominant winds during winter that contribute to the accumulation of fresh water over the shelf.


runoff; river plumes; buoyant flux; climatology; Ría de Vigo; Iberia

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Álvarez-Salgado, X.A., J. Gago, B.M. Míguez, M. Gilcoto and F.F. Pérez. – 2000. Surface waters of the NW Iberian margin: Upwelling on the shelf versus outwelling of upwelled waters from the ‘Rías Baixas’. Est. Coast. Shelf Sci. 51(6): 821-837. doi:10.1006/ecss.2000.0714

Álvarez-Salgado, X.A., J.L. Herrera, J. Gago, P. Otero, J.A. Soriano, C.G. Pola, C. García-Soto. – 2006. Influence of the oceanographic conditions during spring 2003 on the transport of the Prestige tanker fuel oil to the Galician coast. Mar. Pollut. Bull., Prestige Special Issue, 53(5-7): 239-249.

Baumgartner, A. and E. Reichel. – 1975. The world water balance: mean annual global, continental and maritime precipitation, evaporation and run-off. 179 pp. Elsevier. Amsterdam.

Bakun, A. – 1973. Coastal upwelling indices, west coast of North America, 1946-71. U.S. Dept. of Commerce NOAA Technical Report NMFS Special Scientific Report, Fisheries #671: 1-103.

Dai, A.G. and K.E. Trenberth. – 2002. Estimates of freshwater discharge from continents: latitudinal and seasonal variations. J. Hydrometeo., 3(6): 660-687. doi:10.1175/1525-7541(2002)003<0660:EOFDFC>2.0.CO;2

Doval, M.D., E. Nogueira and F.F. Pérez. – 1998. Spatio-temporal variability of the thermohaline and biogeochemical properties and dissolved organic carbon in a coastal embayment affected by upwelling: the Ría de Vigo (NW Spain). J. Mar. Syst., 14(1-2): 135-150. doi:10.1016/S0924-7963(97)80256-4

Esteban-Parra, M.J., F.S. Rodrigo and Y. Castro-Diez. – 1998. Spatial and temporal patterns of precipitation in Spain for the period 1880-1992. Int. J. Climatol., 18(14): 1557-1574. doi:10.1002/(SICI)1097-0088(19981130)18:14<1557::AID-JOC328>3.0.CO;2-J

Fekete, B.M., C.J. Vörösmarty and W. Grabs. – 2002. High-resolution fields of global runoff combining observed river discharge and simulated water balances. Global Biogeochem. Cycles, 16(3): 1042. doi:10.1029/1999GB001254

Fraga, F. and R. Margalef. – 1979. Las Rías gallegas. In: Estudio y explotación del mar en Galicia, pp. 101-121. Secretariado de Publicaciones de la Universidad (Santiago de Compostela).

Hagemann, S. and L. Dümenil. – 1998. A parameterization of the lateral waterflow for the global scale. Clim. Dyn., 14(1): 17-31. doi:10.1007/s003820050205

Herrera, J.L., R.A. Varela, G. Rosón and S. Piedracoba. – 2006. Variability of the western Iberian buoyant plume over the Galician shelf: wind forcing and runoff variability. In: I. Álvarez, M. de Castro, M. Gómez-Gesteria, M.N. Lorenzo and R. Prego (eds.), Oceanography of the Bay of Biscay, pp. 281-284.

Herrera, J.L., G. Rosón, R.A. Varela and S. Piedracoba. – 2008. Variability of the western Galician upwelling system (NW Spain) during an intensively sampled annual cycle. An EOF analysis approach. J. Mar. Sys., 72(1-4): 200-217. doi:10.1016/j.jmarsys.2007.07.007

López-Jurado, J.L.M. – 1985. Notas climatológicas e hidrológicas de las Rías Bajas. Inf. Téc. IEO, 23: 1-13.

Lorenzo, M.N. and J.J. Taboada. – 2005. Influences of atmospheric variability on freshwater input in Galician Rías in winter. J. Atmos. Ocean Sci., 10(4): 377-387. doi:10.1080/17417530601127472

Montero, P., M. Gómez-Gesteira, J.J. Taboada, M. Ruiz-Villarreal, A.P. Santos, R.R. Neves, R. Prego and V. Pérez-Villar. – 1999. On residual circulation of the Ría de Vigo, using a 3-D baroclinic model. Bol. Inst. Español Oceanogr., 15(1-4): 31-38.

Nogueira, E., F.F. Perez and A.F. Rios. – 1997. Seasonal patterns and long-term trends in an estuarine upwelling ecosystem (Ría de Vigo, NW Spain). Est. Coast. Shelf Sci., 44(3): 285-300. doi:10.1006/ecss.1996.0119

Otero, P., M. Ruiz-Villarreal and A. Peliz. – 2008. Variability of river plumes off Northwest Iberia in response to wind events. J. Mar. Syst., 72(1-4): 238-255 doi:10.1016/j.jmarsys.2007.05.016

Otto, L. – 1975. Oceanography of the ría de Arosa (NW Spain). Konink Meteor. Int. Medelingen en Verhandelingen, 96: 1-210.

Piedracoba, S., X.A. Álvarez-Salgado, G. Rosón and J.L. Herrera. – 2005. Short-time scale thermohaline variability and residual circulation in the central segment of the coastal upwelling system of the Ría de Vigo (northwest Spain) during four contrasting periods. J. Geophys. Res., 110, C03018. doi:10.1029/2004JC002556

Prego, R., F. Fraga and A.F. Ríos. – 1990. Water interchange between the Ría de Vigo and the coastal shelf. Sci. Mar., 54(1): 95-100.

Ribeiro, A.C., A. Peliz and A.M.P. Santos, 2005. A study of the response of the chlorophyll-a biomass to a winter upwelling event off Western Iberia using SeaWiFS and in situ data. J. Mar. Sys., 53(1-4): 87-107. doi:10.1016/j.jmarsys.2004.05.031

Ríos, A.F., M.A. Nombela, F.F. Pérez, G. Rosón and F. Fraga. – 1992. Calculation of runoff to an estuary. Ría de Vigo. Sci. Mar., 56(1): 29-33.

Rodríguez-Puebla, C., A.H. Encinas and J. Sáenz. – 2001. Winter precipitation over the Iberian Península and its relationship to circulation indices. Hydrol. Earth Syst. Sci., 5(2): 233-244.

Rosón, G., F.F. Pérez, X.A. Álvarez-Salgado and A.F. Ríos. – 1991. Flujos y características químicas de los aportes de agua continental a la Ría de Arosa. Sci. Mar., 55(4): 583-589.

Ruiz-Villarreal, M., K. Bolding, H. Burchard and E. Demirov. – 2005. Coupling of the GOTM turbulence model to some three-dimensional ocean models. In: H.Z. Baumert, J.H. Simpson and J. Sundermann (eds.), Marine Turbulence: Theories, Observations and Models, pp. 225-237. Cambridge Univ. Press.

Ruiz-Villarreal, M., C. González-Pola, G. Díaz del Río, A. Lavín, P. Otero, S. Piedracoba and J.M. Cabanas. – 2006. Oceanographic conditions in North and Nortwest Iberia and their influence on the Prestige oil spill. Mar. Pollut. Bull. 53(5-7): 220-238. doi:10.1016/j.marpolbul.2006.03.011 PMid:16698046

Santos, A.M.P., Á. Peliz, J. Dubert, P.B. Oliveira, M.M. Angélico and P. Ré. – 2004. Impact of a winter upwelling event on the distribution and transport of sardine (Sardina pilchardus) eggs and larvae off western Iberia: a retention mechanism. Cont. Shelf Res., 24 (2): 149-165. doi:10.1016/j.csr.2003.10.004

Serrano, A., A.J. García, V.L. Mateos, M.L. Cancillo and J. Garrido.– 1999. Monthly modes of variation of precipitation over the Iberian Peninsula. J. Clim., 12(9): 2894-2919 doi:10.1175/1520-0442(1999)012<2894:MMOVOP>2.0.CO;2

Torres, R. and E.D. Barton. – 2007. Onset of the Iberian upwelling along the Galician coast. Cont. Shelf Res., 27(13): 1759-1778. doi:10.1016/j.csr.2007.02.005

Trigo, R.M. and C.C. DaCamara. – 2000. Circulation weather types and their impact on the precipitation regime in Portugal. Int. J. Climatol., 20(13): 1559-1581. doi:10.1002/1097-0088(20001115)20:13<1559::AID-JOC555>3.0.CO;2-5

Varela, R.A., G. Rosón, J.L. Herrera, S. Torres-López and A. Fernández-Romero. – 2005. A general view of the hydrographic and dynamical patterns of the Rías Baixas adjacent area. J. Mar. Sys., 54(1-4): 97-113. doi:10.1016/j.jmarsys.2004.07.006

Vergara, J. and R. Prego. – 1997. Estimación de los aportes fluviales de nitrato, fosfato y silicato hacia las Rías Gallegas. Procesos biogeoquímicos en sistemas costeros hispano-lusos: VIII Seminario Ibérico de Química Marina: 33-40, ISBN 84-89690-27-8.

Zorita, E., V. Kharin and H. von Storch. – 1992. The atmospheric circulation and sea surface temperature in the North Atlantic area in winter: their interaction and relevance for Iberian precipitation. Int. J. Climatol., 5(10): 1097-1108. doi:10.1175/1520-0442(1992)005<1097:TACASS>2.0.CO;2

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