The role of the Siberian high in northern hemisphere climate variability
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Citation Cohen, Judah, Kazuyuki Saito, and Dara Entekhabi. “The Role of the Siberian High in Northern Hemisphere Climate Variability.” Geophysical Research Letters 28.2 (2001): 299–302. © 2001 by the American Geophysical Union
As Published http://dx.doi.org/10.1029/2000GL011927
Publisher American Geophysical Union (AGU)
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Citable link http://hdl.handle.net/1721.1/110326
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The role of Siberian High in Northern Hemisphere climate variability
Article in Geophysical Research Letters · January 2001 DOI: 10.1029/2000GL011927
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The role of the Siberian high in Northern Hemisphere climate variability
Judah Cohen Atmospheric and Environmental Research, Inc., Cambridge, Massachusetts
KazuyukiSaio and Data Enekhabi Massachusetts Institute of Technology Cambridge, Massachusetts
Abstract. The dominantmode of sea level pressure(SLP) Eurasian snow cover has large interannual variability and variability during the winter months in the Northern Hemi- heating anomalies forced by snow cover in the region of the sphere(NH) is characterizedby a dipole with one anomaly Siberian high can propagate remotely through favorable at- center covering the Arctic with the opposite sign anomaly mospheric teleconnection patterns. As with SSTs, anoma- stretched across the mid-latitudes. Associated with the SLP lies occur on relatively large scales and the residence time anomaly, is a surface temperature anomaly induced by the of anomaliesrange from weeks[Clark and Serreze,2000] to anomalous circulation. We will show that this anomaly pat- months [Iwasaki, 1991; Walland and Simmonds,1997; Co- tern originates in the early fall, on a much more regional hen and Entekhabi,1999]. In this letter, we demonstrate scale, in Siberia. As the season progresses this anomaly associationsbetween the Siberian high and remote regional pattern propagates and amplifies to dominate much of the climates on seasonaltime scalesand suggestthe importance extratropical NH, making the Siberian high a dominant force of snow cover to this teleconnection. in NH climate variability in winter. Also since the SLP and Results surface temperature anomalies originate in a region of max- imum fall snow cover variability, we argue that snow cover The dominant mode of variability for December, January partially forces the phase of winter variability and can po- and February (DJF) NH SLP has been describedas two tentially be used for the skillful prediction of winter climate. phasesof an Arctic high/low SLP centerbarotropically cou- pled with the stratosphere[Thompson and Wallace,1998] Introduction or the expansion/contractionof the Siberian high, forced in part by seasonalsurface heating anomalies[Cohen and Over the past decade great strides have been made in Entekhabi,1999]. What has been lackingin previousstud- understanding how heating anomalies in one region of the ies, is more definitive demonstration of the origins of the globe can force the overlying atmosphere to deviate from its DJF SLP anomaly, which stretches from Siberia across the mean state in a consistent and predictable manner. This North Pole into North America and the North Atlantic. To deviation from normal can then propagate from the local show this, grid point values of SLP and surface tempera- heating anomaly to remote regions around the globe. For ture (Ts) are correlatedwith geopotentialheights [Kalnay example, E1-Nifio/SouthernOscillation (ENSO) describes et al., 1996]and snowcover [Robinson et al., 1993]for 1972- quasi-periodic anomaly patterns in sea surface temperatures 1999. Since there could be some issue with the accuracy of (SSTs) which are confinedto the tropical Pacific Ocean reanalysis data over data-sparse regions including the Arc- basin. Yet, ENSO through atmospheric teleconnection pat- tic, therefore, we checked the reanalysis data with in-situ terns, influencesregional climates around the globe [Barn- observed data from the International Arctic Buoy Program ston, 1994]. [Thorndikeand Colony,1980] and found them to be nearly In the NH mid- to high-latitude cold season there are equivalentfor the Arctic region(monthly root mean square three semi-permanent and quasi-stationary surface features error
299 300 COHEN ET AL' ROLE OF SIBERIAN HIGH
a) 0r'4 I - Nov 1,5 b) 0v! 15 - Nov 30
Nov15 - Dec31_ e} Dec! - Jan15
Figure 1. Maps(shading .38 = 95%,.49 = 99%significance) of DJF upper-AO(see text fordefinition) correlated with approximately 45 day averageNH griddedSLP for (a) Oct. 1- Nov. 15 (b) Oct. 15- Nov. 30 (c) Nov. 1- Dec. 15 (d) Nov. 15- Dec. 31 (e) Dec. i - Jan. 15 (f) Dec. 15 - Jan. 31. Solidpurple thick lines in a-e are 1000meter isopleth. 27 yearsof data includedfrom Sept. 1972- Feb. 1999. Regionof light blueshading for correlationsgreater than .38 and dark blue for correlationsgreater than .49. Orangefor correlations less than -.38 and red for correlations less than -.49. weeks in the same season. We then correlated the time se- agates west with the snowlinebut is shifted to the south- ries of the upper level signal for D JF with gridded 45-day east, consistentwith the snow-inducedheating anomaly be- averagedSLP (Figure1) and Ts (Figure2), beginningwith ing advected downstream. The initial propagation is west October 1. because during October and November the waters of the Figure I showsthat starting in October, SLP anomalies Arctic Ocean in the Barents and Kara Seas are still un- first appear in eastern Siberia. The initial SLP anomaly frozen. Starting in late fall and early winter, propagation developsover the anomaloussnow cover and the resultant commences to the north across the now frozen Arctic Ocean heating anomaly,and then propagatesto the west with the [Gloersenet al., 1992].Due to the shallownessof the dense, advancing snowline. The temperature anomaly also prop- cold air associated with the Siberian high, its expansion is
Dec I - Jan 15
Figure 2. Sameas Figurei exceptupper-AO correlated with griddedTs 45 day averages.Region of orangeshading for correlations greaterthan .38 and red for correlationsgreater than .49. Light blue for correlationsless than -.38 and dark blue for correlationsless than -.49. COHEN ET AL- ROLE OF SIBERIAN HIGH 301
Nov 15 b) Oct 15 -..Not' 30 e) Nox, ! - Dee 15
d) Nov 15 - Dee31 e) Dec-I - Jan 1,5 f) Dee 15 - Jan 31
.. -. .,< 2,
•".:--."•"?. X ',' :.... ? -. If... :X/.-, : •' " '...... ':: :: ")[kr"•%•'" :-'..... ;' :• •' . -• '• . -- ,[ :,'
.•. • ......
Figure 3. Same as Figure 1 except SON Eurasian snow cover correlatedwith gridded SLP 45 day averages(contours every .10). Region of light blue shading for correlations greater than .38 and dark blue for correlations greater than .49. Orange for correlations less than -.38 and red for correlations less than -.49. restricted by high topography. The 1000-meter above sea ally across the entire Arctic into North America and the leveltopographic contour (thick line in figures)clearly illus- North Atlantic. Correlations indicate much of signal in this trates how the SLP anomaly emanating from the Siberian region to be significant at greater than the 95% confidence high is constrained by the high topography not only in Eura- value. At lower latitudes in Western Europe and eastern sia but even in North America. During winter (simultane- North America SLP anomalies, of opposite sign from the ous uAO and SLP) the correlationplot is almost identical SLP anomaly over the Arctic, also appear. This resembles to the definedArctic Oscillation[Thompson and Wallace, Figure 1 and the dominant mode of variability for DJF SLP. 1998]. Correlation'of the time seriesfrom the SLP-derived- Tests for field significanceshow SON snow cover and DJF AO with the same45-day periodsgives similar results(not SLP to be highly significant. shown). Figures 1-3 demonstrate that: both snow cover and the The surfacetemperature anomaly (Figure 2) also prop- stratospheric polar vortex are associatedwith the dominant agates first westward and then northward with the SLP mode of variability of DJF NH SLP; this mode is inherently anomaly. The Ts anomaly, similar to the SLP anomaly, is constrained by the high topography in central and western Asia during winter. However, unlike the SLP anomaly, the SLP/Snow index anomaly 1972-1998 Ts anomaly propagates southward, lee of the high topog- raphy in eastern Asia. This is consistentwith the positive correlation of the frequency of East Asian cold surges and the strengthof the Siberianhigh [Yihui, 1990]. It has already been shown that September, October, November(SON) Eurasiansnow cover anomalies are signif- icantly correlated with D JF SLP and 500 hPa geopotential Year heights particularly in the Arctic and North Atlantic sec- tors [Cohenand Entekhabi,1999]. In Figure 3 we provide SLP/Snow index anomaly t97•- 1998 •:. AO at 500 hPa DJF (• further statistical evidence that the dominant mode of SLP • $LP/Snowindex Oct .J variability may be partially forced by snow cover variability. t• -- To isolate the dominant role of surface heating anomalies •: ...... • •--- due to interannual variability in snow cover across Eura- sia, the Eurasian snow cover extent time series in the fall ß-:: R=.70 --: ...... season is used as a climate index. Snow cover extent is 970 1980 1990 2000 defined as the areal snow cover for Eurasia in millions of Year squaredkilometers [Robinson et al., 1993]. In Figure 3 we present a seriesof plots of the correlation of Eurasian SON Figure 4. (a) Plot of Arctic Oscillation (AO) for DJF and SLP/snow index for October (see text for definition). Correla- snow cover area with the same gridded 45-day averaged SLP tion (R) betweentwo time seriesis also shown. (b) Plot of time as shown in Figure 1. Initially a perturbed region of SLP series of leading mode of variability of 500 hPa geopotential height in eastern Siberia expands westward following the snowline field (AO at 500 hPa) for DJF and SLP/snow index for October. acrossnorthern Russian and northern Europe and eventu- Correlation (R) between two time seriesis also shown. 302 COHEN ET AL.: ROLE OF SIBERIAN HIGH linked to the expansionand contraction of the Siberian high we would like to thank Dr. Martyn Clark and an anonymous acrossthe Arctic; and the early seasonEurasian snow cover reviewer for improving the quality of the manuscript. is a forcingmechanism (or at the very leasta proxy) for the subsequentNH winter climate. We also note that signifi- References cantcorrelations are consistently found in themid to high- Baldwin, M.P. and T.J. Dunkerton. Propagation of the Arctic latitudes of the Arctic, Atlantic Oceans and the Eurasian Oscillation from the stratosphere to the troposphere. J. Geo- and eastern North American continents but not the Pacific phys. Res., l OJ, 30937-30946, 1999. Ocean. This is consistent with the observational evidence Barnston, A.G. Linear Statistical short-term climate predictive skill in the Northern Hemisphere. J. Climate, 7, 1513-1564, and GCM results which show that the dominant mode of NH 1994. climatevariability is not a zonally symmetricmode [Deser, Cohen, J. The potential use of snow cover variability for Northern 2000; Monahanet al., 2000]. Hemisphere climate prediction. In T. Barnston and E. O'Lenic, editors, Proc. 2Jth Annual Climate Diagnostics and Prediction Workshops, 240-243, 1999. Conclusions Cohen, J. and D. Entekhabi. Eurasian snow cover variability and Northern Hemisphere climate predictability. Geophys. Res. In this letter we present evidence that for the cool season, Let., 26, 345-348, 1999. underneath the seemingly haphazard passage of weather Clark, M.P. and M.C. Serreze. Effects of variations in east Asian events, the background unfolds in a systematic and pre- snow cover on modulating atmospheric circulation over the dictable manner acrosslarge regions of the NH. As summer North Pacific Ocean. J. Climate, in Press. turns to fall in northern Eurasia, the Siberian high strength- Deser, C. On the teleconnectivity of the "Arctic Oscillation". Geophy. Res. Let., 27, 779-782, 2000. 297-1300, 1998. ens and spreadsunder increased divergence. If anomalously Foster, J., M. Owe and A. Rango. Snow cover and temperature high snow cover is present, colder air temperatures result relationships in North America and Eurasia. J. Clim. Appl. in strengthened or anomalous high pressure;less snow cover Meteor., 22, 460-469, 1983. results in anomalouslow pressure. Propagation of the SLP Gloersen, P., W.J. Campbell, D.J. Cavalieri, J.C. Comiso, C.L. anomaly commencesto the west towards westernRussia and Parkinson and H.J. Zwally. Arctic and Antarctic sea ice, 1978- 1987: Satellite passive-microwave observations and analysis. northern Europe. As fall turns to winter propagation to Tech. Rep. $P-511, 290 pp., National Aeronautics and Space the west is eventually restricted by the strong maritime in- Administration, Washington, D.C., 1992. fluence of the North Atlantic and the Gulf Stream in Eu- Iwasaki., T. Year-to-year variation of snow cover area in the rope. With the Arctic Ocean becoming nearly completely Northern Hemisphere. J. Meteor. $oc. Jap., 169, 209-217, frozen by early December, the preferred route of expansion 1991. Kalnay, E. and Coauthors.The NCEP/NCAR 40-Year reanalysis changesfrom west to north, and the Siberian high now ex- project. Bull. Amer. Meteor. Soc., 77, 437-471, 1996. pands northward over the frozen Arctic into North America. Monahan, A.H., J.C. Fyfe and G.M. Flato. A regime view of Not surprisingly,the phase of the Arctic Oscillation is most Northern Hemisphere Atmospheric variability and change un- strongly correlated with sea ice concentration in the same der global warming. Geophy. Res. Let., 27, 1139-1142, 2000. region of the initial propagation of the SLP anomaly from Mysak, L.A. and S.A. Venegas. Decadal climate oscillations in the Arctic: A new feedback loop for atmosphere-ice-ocean in- the northerncoast of Eurasiainto the Arctic Ocean[Mysak teractions. Geophys. Res. Let., 25, 3607-3610, 1998. and Venegas,1998]. Robinson, D. A., F. Dewey and R. Heim Jr. Northern Hemi- Hence we provide a methodological framework which de- spheric snow cover: An update. Bull. Amer. Meteor. Soc., scribes how topography, snow cover, the juxtaposition of 1689-1696, 1993. land and ocean masses, and sea ice dictate the manner in Sahsamanoglou, H.S., T.J. Makrogiannis and P.P. Kallimopou- los. Some aspects of the basic characteristics of the Siberian which cold, dense air spreads out from its source region in anticyclone. Int. J. Climatol., 11, 827-839, 1991. Siberia acrosslarge tracts of frozen land and ice in the Arc- Thompson, D. W. J. and J. M. Wallace. The Arctic Oscillation tic and North Atlantic sectors. This work even has poten- signature in the wintertime geopotential height and tempera- tial ramifications for paleoclimate studies. It provides a new ture fields. Geophys. Res. Let., 25, 1297-1300, 1998. mechanismfor linking the uplift of the Tibetan Plateau with Thorndike, A.S. and R. Colony. Arctic Ocean Buoy Program Data January 1979- December 1979. Tech. Rep. 19, 131 pp., Polar the inception of ice sheet growth in the North Atlantic sec- Science Center, University of Washington, Seattle, Washing- tor. But besidesthe theoretical application of our results to ton, 1980. different climate disciplines, this work has immediate prac- Walland, D. J. and I. Simmonds. North American and Eurasian tical application. As a demonstration of the potential pre- snow cover co-variability. Tellus, J9A, 503-512, 1997. dictive value of the analysis presented, we plot the AO for Yihui., D. Build-up, air mass transformation and propagation of Siberian high and its relation to cold surge in East Asia. SLP and 500 hPa geopotential heights for D JF with an in- Meteorol. Atmos. Phys., 44, 281-292, 1990. dex constructed from SLP and snow cover from October in
Fig. 4. The index was constructed from the multiple linear J. Cohen, Atmospheric and Environmental Research, Inc., 840 regressionof Eurasian snow cover extent and the absolute Memorial Drive, Cambridge,MA 02139. (email: [email protected]) value of SLP centered at 67.5øN and 150øE, both for Oc- K. Saito, Frontier Research System for Global Change SEA- tober. Correlationof the SLP/snow index and the AO for VANS North 7F, 1-2-1 Shibaura, Minato-ku, Tokyo 105-6791 SLP and 500 hPa geopotential heights are .69 and .70 respec- Japan (e-mail: ksaitø@frøntier'estø'ør'jp) tively. It has already been shown that the use of snow cover D. Entekhabi, Parsons Laboratory, Massachusetts Institute of Technology,Cambridge, MA 02139. (e-mail: [email protected]) anomalies to predict surface temperature and precipitation has demonstrableskill [Cohen,1999].
Acknowledgments. This investigationwas supportedby NSF grant ATM-9902433. We would like to thank Dr. David Robinson for providing us with snow cover data and Drs. Rick (ReceivedJune 20, 2000; revisedSeptember 19, 2000; Rosen and David Salstein for many beneficial discussions. Finally acceptedSeptember 21, 2000.)
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