Abstract
The intraseasonal variability of the frontal activity and its connection with the variability of the atmospheric circulation and precipitation in the Southern Hemisphere is studied. The frontal activity is defined as the relative vorticity times the local temperature gradient. A band-pass filter was applied to retain the intraseasonal timescales. An empirical orthogonal function analysis was applied to the filtered frontal activity anomalies. The two main modes show positive and negative centers located mainly over the southern Pacific Ocean and South American sector and are in quadrature with each other. A similar pattern was found when the main modes of intraseasonal variability of the 500 hPa geopotential height were projected on the frontal activity, suggesting that the variability of fronts are influenced by the variability of the large scale atmospheric circulation. Moreover, the precipitation anomalies projected on the main modes of both frontal activity and 500 hPa geopotential height show similar structures, especially over the southern Pacific Ocean and South America, which may indicate that the variability of fronts controls the variability of precipitation. The lagged regression of the time series of the frontal activity areally-averaged over one of the centers of action against the frontal activity anomaly field shows at lags −8 and 8 a similar pattern, suggesting a period of around 17 days for each mode. Moreover, lagged regression between times series of frontal activity and precipitation anomalies reveals an opposite pattern between southeastern South America and southern Chile, being precipitation anomalies over these two regions anti-correlated due to the frontal activity.
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Alvarez MS, Vera CS, Kiladis GN, Liebmann B (2014) Intraseasonal variability in South America during the cold season. Clim Dyn 42:3253–3269. doi:10.1007/s00382-013-1872-z
Berbery EH, Vera CS (1996) Characteristics of the Southern Hemisphere storm track with filtered and unfiltered data. J Atmos Sci 53:468–481. doi:10.1175/1520-0469(1996)053<0468:COTSHW>2.0.CO;2
Bjerknes J, Solberg H (1922) Life cycle of cyclones and the polar front theory of atmospheric circulation. Geophysisks Publikationer 3:1–18
Browning KA, Roberts NM (1994) Structure of a frontal cyclone. Q J R Meteorol Soc 120:1535–1557. doi:10.1002/qj.49712052006
Catto JL, Jakob C, Berry G, Nicholls N (2012) Relating global precipitation to atmospheric fronts. Geophys Res Lett 39:LI0805. doi:10.1029/2012GL051736
Cavalcanti IFA, Kayano MT (1999) High-frequency patterns of the atmospheric circulation over the Southern Hemisphere and South America. Meteorol Atmos Phys 69:179–193. doi:10.1007/BF01030420
Cunningham CAC, Cavalcanti IFA (2006) Intraseasonal modes of variability affecting the South Atlantic Convergence Zone. Int J Climatol 26:1165–1180. doi:10.1002/joc.1309
Duchon CE (1979) Lanczos filtering in one and two dimensions. J Appl Meteorol 18:1016–1022. doi:10.1175/1520-0450(1979)018<1016:LFIOAT>2.0.CO;2
Ghil M, Mo K (1991) Intraseasonal oscillations in the global atmosphere. Part II: Southern Hemisphere. J Atmos Sci 48:780–790. doi:10.1175/1520-0469(1991)048<0780:IOITGA>2.0.CO;2
Gonzalez PLM, Vera C (2014) Summer precipitation variability over South America on long and short intraseasonal timescales. Clim Dyn 43:1993–2007. doi:10.1007/s00382-013-2023-2
Hannachi A, Jolliffe IT, Stephenson DB (2007) Empirical orthogonal functions and related techniques in atmospheric science: a review. Int J Climatol 27:1119–1152. doi:10.1002/joc.1499
Kidson JW (1988) Indices of the Southern Hemisphere zonal wind. J Clim 1:183–194. doi:10.1175/1520-0442(1988)001<0183:IOTSHZ>2.0.CO;2
Kidson JW, Sinclair MS (1995) The influence of persistent anomalies on Southern Hemisphere storm tracks. J Clim 8:1938–1950. doi:10.1175/1520-0442(1995)008<1938:TIOPAO>2.0.CO;2
Liebmann B, Kiladis GN, Marengo JA, Ambrizzi T, Glick JD (1999) Submonthly convective variability over South America and the South Atlantic Convergence Zone. J Clim 12:1877–1891. doi:10.1175/1520-0442(1999)012<1877:SCVOSA>2.0.CO;2
Mo KC, Ghil M (1987) Statistics and dynamics of persistent anomalies. J Atmos Sci 44:877–902. doi:10.1175/1520-0469(1987)044<0877:SADOPA>2.0.CO;2
Mo KC, Higgins RW (1998) The Pacific-South American modes and tropical convection during the Southern Hemisphere winter. Mon Weather Rev 126:1581–1596. doi:10.1175/1520-0493(1998)126<1581:TPSAMA>2.0.CO;2
Nogués-Paegle J, Mo KC (1997) Alternating wet and dry conditions over South America during summer. Mon Weather Rev 125:279–291. doi:10.1175/1520-0493(1997)125<0279:AWADCO>2.0.CO;2
Pook MJ, McIntosh PC, Meyers GA (2006) The synoptic decomposition of cool-season rainfall in the southeastern Australian cropping region. J Appl Meteorol Climatol 45:1156–1170. doi:10.1175/JAM2394.1
Richman MB (1986) Rotation of principal components. J Climatol 6:293–335
Robertson AW, Mechoso CR (2003) Circulation regimes and low-frequency oscillations in the South Pacific sector. Mon Weather Rev 131:1566–1576. doi:10.1175//2548.1
Solman SA, Orlanski I (2010) Subpolar high anomaly preconditioning precipitation over South America. J Atmos Sci 67:1526–1542. doi:10.1175/2009JAS3309.1
Solman SA, Orlanski I (2014) Poleward shift and change of the frontal activity in the Southern Hemisphere over the last 40 years. J Atmos Sci 71:539–552. doi:10.1175/JAS-D-13-0105.1
Thompson DWJ, Wallace JM (2000) Annular modes in the extratropical circulation. Part I: month-to-month variability. J Clim 13:1000–1016. doi:10.1175/1520-0442(2000)013<1000:AMITEC>2.0.CO;2
Uppala SM et al (2005) The ERA-40 re-analysis. Q J R Meteorol Soc 131:2961–3012. doi:10.1256/qj.04.176
Vera C (2003) Interannual and interdecadal variability of atmospheric synoptic-scale activity in the Southern Hemisphere. J Geophys Res 108(C4):8077. doi:10.1029/2000JC000406
Xie P, Chen M, Yang S, Yatagai A, Hayasaka T, Fukushima Y, Liu C (2007) A gauge-based analysis of daily precipitation over East Asia. J Hydrometeorol 8:607–626. doi:10.1175/JHM583.1
Acknowledgments
The authors are grateful to Dr. Isidoro Orlanski for his insightful comments and suggestions on the manuscript. The authors also thank to two anonymous reviewers for their valuable comments that helped to improve this paper. This work was supported by the following grants: FONCyT—PICT-2012-1972, PIP-CONICET No. 112-201101-00189 and UBACYT2014 No. 20020130200233BA.
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Blázquez, J., Solman, S.A. Intraseasonal variability of wintertime frontal activity and its relationship with precipitation anomalies in the vicinity of South America. Clim Dyn 46, 2327–2336 (2016). https://doi.org/10.1007/s00382-015-2704-0
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DOI: https://doi.org/10.1007/s00382-015-2704-0