Dependence of winter precipitation over Portugal on NAO and baroclinic wave activity
1999; Wiley; Volume: 19; Issue: 4 Linguagem: Inglês
10.1002/(sici)1097-0088(19990330)19
ISSN1097-0088
AutoresUwe Ulbrich, M. Christoph, Joaquim G. Pinto, João Corte‐Real,
Tópico(s)Oceanographic and Atmospheric Processes
ResumoInternational Journal of ClimatologyVolume 19, Issue 4 p. 379-390 Research Article Dependence of winter precipitation over Portugal on NAO and baroclinic wave activity U. Ulbrich, Corresponding Author U. Ulbrich Institut für Geophysik und Meteorologie, Universität zu Köln, 50923 Köln, GermanyInstitut für Geophysik und Meteorologie, Universität zu Köln, 50923 Köln, GermanySearch for more papers by this authorM. Christoph, M. Christoph Max-Planck-Institut für Meteorologie, Bundesstr. 55, 20146 Hamburg, GermanySearch for more papers by this authorJ.G. Pinto, J.G. Pinto ICAT, Ed. ICAT, Campus da Faculdade de Ciencias, Campo Grande, 1700 Lisboa, PortugalSearch for more papers by this authorJ. Corte-Real, J. Corte-Real ICAT, Ed. ICAT, Campus da Faculdade de Ciencias, Campo Grande, 1700 Lisboa, PortugalSearch for more papers by this author U. Ulbrich, Corresponding Author U. Ulbrich Institut für Geophysik und Meteorologie, Universität zu Köln, 50923 Köln, GermanyInstitut für Geophysik und Meteorologie, Universität zu Köln, 50923 Köln, GermanySearch for more papers by this authorM. Christoph, M. Christoph Max-Planck-Institut für Meteorologie, Bundesstr. 55, 20146 Hamburg, GermanySearch for more papers by this authorJ.G. Pinto, J.G. Pinto ICAT, Ed. ICAT, Campus da Faculdade de Ciencias, Campo Grande, 1700 Lisboa, PortugalSearch for more papers by this authorJ. Corte-Real, J. Corte-Real ICAT, Ed. ICAT, Campus da Faculdade de Ciencias, Campo Grande, 1700 Lisboa, PortugalSearch for more papers by this author First published: 14 April 1999 https://doi.org/10.1002/(SICI)1097-0088(19990330)19:4 3.0.CO;2-8Citations: 84AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract The relationship between winter (DJF) rainfall over Portugal and the variable large scale circulation is addressed. It is shown that the poles of the sea level pressure (SLP) field variability associated with rainfall variability are shifted about 15° northward with respect to those used in standard definitions of the North Atlantic Oscillation (NAO). It is suggested that the influence of NAO on rainfall dominantly arises from the associated advection of humidity from the Atlantic Ocean. Rainfall is also related to different aspects of baroclinic wave activity, the variability of the latter quantity in turn being largely dependent on the NAO. A negative NAO index (leading to increased westerly surface geostrophic winds into Portugal) is associated with an increased number of deep (ps<980 hPa) surface lows over the central North Atlantic and of intermediate (980<ps<1000 hPa) surface lows over North-western Europe. It is suggested that these distant surface lows have no direct influence on local Portuguese precipitation, but rather contribute to advection at their southern flanks. The other aspect of baroclinic wave activity varying with the NAO is the mid-tropospheric storm track (defined by the 500 hPa bandpass-filtered geopotential height variance). A possible local influence of the storm track due to vertical motions ahead of the upper air troughs cannot be unambiguously separated from the effect of advection. A separate influence of local surface cyclones over the Iberian peninsula which may, for instance, arise from the large scale ascent of air, is revealed by the statistics: for a given advection, rainfall amounts for months with local cyclone cores over the considered region tend to exceed those without. Copyright © 1999 Royal Meteorological Society References Blackmon, M.L. 1976. 'A climatological spectral study of the 500 mb geopotential height of the northern hemisphere', J. Atmos. Sci., 33, 1607–1623. Born, K. and Flohn, H. 1997. 'The detection of changes in baroclinicity and synoptic activity on the northern hemisphere for the period 1967–1994', Meteorol. Zeitschrift, N.F., 6, 51–59. Christoph, M., Ulbrich, U. and Haak, U. 1995. 'Faster determination of the intraseasonal variability of storm tracks using Murakami's recursive filter', Mon. Wea. Rev., 123, 578–581. Christoph, M., Ulbrich, U. and Speth, P. 1997. 'Midwinter suppression of northern hemisphere storm track activity in the real atmosphere and in GCM experiments', J. Atmos. Sci., 54, 1589–1599. Deser, C. and Blackmon, M. 1993. 'Surface climate variations over the North Atlantic ocean during winter: 1900–1989', J. Climate, 6, 1743–1753. Haak, U. 1993. Variabilität der synoptisch-skaligen Aktivität außerhalb der Tropen unter klimatologischen Aspekten, PhD thesis, Mitteilungen aus dem Institut für Geophysik und Meteorologie der Universität zu Köln, Vol. 95, 153 pp., ISSN 0069-5882. Haak, U. and Ulbrich, U. 1996. 'Verification of an objective cyclone climatology for the North Atlantic', Meteorologische Zeitschrift, N.F., 5, 24–30. Hurrell, J.W. 1995. 'Decadal trends in the North Atlantic oscillation and regional temperature and precipitation', Science, 269, 676–679. Hurrell, J.W. and van Loon, H. 1997. 'Decadal variations in climate associated with the North Atlantic oscillation', Climatic Change, 36, 301–326. Kutzbach, J.E. 1967. 'Empirical eigenvectors of sea-level pressure, surface temperature and precipitation complexes over North America', J. Appl. Meterol., 6, 791–802. Lamb, P.J. and Peppler, R.A. 1987. 'North Atlantic oscillation, concept and an application', Bull. Am. Meteorol. Soc., 68, 1218–1225. Mendes, J.C. 1993. Local Scale Microclimatology and Time Series Analysis, MEDALUS I Final Report. Obtainable from: ICAT, Campus da Faculdade de Ciencias, Campo Grande, 1700 Lisboa, Portugal. Preisendorfer, R.W. 1988. Principal component analysis in meteorology and oceanography, in Developments in Atmospheric Sciences, Vol. 17, Elsevier, Amsterdam, 425 pp. Rodo, X., Baert, E. and Comin, F.A. 1997. 'Variations in seasonal rainfall in Southern Europe during the present century. Relationships with the North Atlantic oscillation and the El Niño-Southern oscillation', Climate Dynamics, 13, 275–284. Rogers, J.C. 1984. 'The association between the North Atlantic oscillation and the Southern oscillation in the northern hemisphere', Mon. Wea. Rev., 112, 1999–2015. Rogers, J.C. 1990. 'Low frequency monthly sea level pressure variability (1899–1986) and associated wave cyclone frequencies', J. Climate, 3, 1364–1379. Rogers, J.C. 1997. On the Cause of Mild Winters in Northern Europe, NCAR Technical Note March 1997 (NCAR/TN-433+PROC), pp. 51–67. Obtainable from: NCAR, Boulder, Colorado 80307, USA. von Storch, H., Zorita, E. and Cubasch, U. 1993. 'Downscaling of global climate change estimates to regional scales, an application to Iberian rainfall in wintertime', J. Climate, 6, 1161–1171. Wallace, J.M. and Gutzler, D.S. 1981. 'Teleconnections in the geopotential height field during the northern hemisphere winter', Mon. Wea. Rev., 109, 784–812. Zorita, E., Kharin, V. and von Storch, H. 1992. 'The atmospheric circulation and sea surface temperature in the North Atlantic area in winter: Their interaction and relevance for Iberian precipitation', J. Climate, 5, 1097–1108. Zhang, X., Wang, X. and Corte-Real, J. 1997. 'On the relationships between daily circulation patterns and precipitation in Portugal', J. Geophys. Res., 102, 13 495–13 507. Citing Literature Volume19, Issue430 March 1999Pages 379-390 ReferencesRelatedInformation
Referência(s)