Evolution of Atmospheric Response to Early-Season Eurasian Snow Cover Anomalies

Saitô, Kazuyuki; Cohen, Judah; Entekhabi, Dara

doi:10.1175/1520-0493(2001)129<2746:eoarte>2.0.co;2

Cited by 92 publications

(92 citation statements)

References 59 publications

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“…The significant role of the high anomaly over the Far East is not surprising given that this is the region of climatological maximum vertical wave activity flux. Saito et al (2001) also emphasized that Siberian High variability may impact the upward flux of planetary waves into the stratosphere. Cold vortex events composite in Limpasuvan et al (2005) also had a precursory signal over the North Pacific.…”

Section: Discussionmentioning

confidence: 99%

Variability of the Northern Hemisphere polar stratospheric cloud potential: the role of North Pacific disturbances

Orsolini

Karpechko

Nikulin

2009

Quart J Royal Meteoro Soc

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ABSTRACT:The potential of the Arctic stratosphere to sustain the formation of Polar Stratospheric Clouds (PSCs) is a key factor in determining the amount of ozone destroyed each winter, and is often measured as a 'PSC volume'. The latter quantity has been shown to closely follow a near-linear compact relationship with winter-averaged column ozone loss, and displays a high variability from monthly to decadal time-scales. We examine the connection between meteorological conditions in the troposphere and the variability of lower polar stratospheric temperatures over the last four decades, and specifically, conditions leading to a high PSC volume. In addition to the well-established connection between the North Atlantic Oscillation (NAO) and the polar vortex, we demonstrate the large influence of precursory disturbances over the North Pacific and the Far East, the region of maximum climatological upward wave activity flux. Namely, very high monthly PSC volume (in the top 12%) predominantly follows the development of positive tropospheric height anomalies over the Far East, which lead to a weakening of the background planetary wave trough, and lessened upward wave activity flux into the stratosphere. Precursory anomalies over the Far East are reminiscent of East Asian monsoon amplification episodes.

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Section: Discussionmentioning

confidence: 99%

Variability of the Northern Hemisphere polar stratospheric cloud potential: the role of North Pacific disturbances

Orsolini

Karpechko

Nikulin

2009

Quart J Royal Meteoro Soc

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“…Bamzai and Shukla (1999) too have documented that there is a close relationship between snow cover extent and surface temperatures over Eurasia. Further, there have been studies in the past that accentuates on boreal autumn (winter) NH snow to be influencing the subsequent (simultaneous) winter AO (Saito et al 2001;Cohen et al 2002;Gong et al 2002). Regional cooling due to excessive snow could potentially create atmospheric effects that propagate to other regions through atmospheric teleconnections (Namias 1985).…”

Section: Testing Of Hypothesis For a Possible Physical Mechanismmentioning

confidence: 99%

“…b Auto-correlation analyses of January SST over the defined box with the SSTs over the same area for the subsequent months from February through December. Dashed line indicates the line of significance at 95% loc for the data period considered from 19821985, 1984, 2002, 1990and 2001while the positive SSTI years are 1987, 1998, 2005, 2004, 1989and 1988. These years are arranged according to its decreasing strength of standard anomalies.…”

Section: Implication Of Cold Sst Anomalies On Neismrmentioning

confidence: 99%

Summer monsoon rainfall variability over North East regions of India and its association with Eurasian snow, Atlantic Sea Surface temperature and Arctic Oscillation

Prabhu

Kim

et al. 2016

Clim Dyn

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Nepal and Bangladesh, is influenced by local and remote forces. In terms of geographical size, NE-India constitutes of about 8% of India's total size. Its population is approximately 40 million, which represents around 3.1% of the total Indian population. This region has a predominantly humid sub-tropical climate with hot, humid summers, severe monsoons and mild winters. Along with the west coast of India, this region has some of the Indian sub-continent's last remaining rain forests, which supports diverse flora and fauna and several crop species. Geographically, two-thirds of the area is a hilly terrain interspersed with valleys and plains. The mean summer monsoon rainfall over the NE-Indian region is around 1400 mm making for huge water and hydropower potential. However, this region has been exhibiting a declining trend in the summer monsoon rainfall since the last 4-5 decades (see Fig. 3, Fig. 4a in Preethi et al. 2016). Hence, it becomes imperative to examine the possible drivers of this variability.Significance for long-term prediction of summer monsoon, considering its massive socio-economic impacts, have been widely attributed to the slowly varying boundary conditions such as sea surface temperature (SST) and snow cover (Shukla 1998). In general, rainfall distribution pattern over different regions of India is inhomogeneous due to influence of several local and remote factors. For instance, over the central Indian plain region, monsoon trough and the Himalayas along with local and external factors play a dominant role in its interannual rainfall variability. Likewise, the northwest region is influenced by the dry climates of the Thar Desert and the Western Himalayas. Apparently from the geographical features as described above, the rain producing mechanism of NE rainfall is a complex phenomenon and is largely dominated by an elevated orography of the Eastern Himalayas and large forests. The NE sector may be considered as a separate macro-region within the Indian Abstract This observational study during the 29-year period from 1979 to 2007 evaluates the potential role of Eurasian snow in modulating the North East-Indian Summer Monsoon Rainfall with a lead time of almost 6 months. This link is manifested by the changes in high-latitude atmospheric winter snow variability over Eurasia associated with Arctic Oscillation (AO). Excessive wintertime Eurasian snow leads to an anomalous cooling of the overlying atmosphere and is associated with the negative mode of AO, inducing a meridional wave-train descending over the tropical north Atlantic and is associated with cooling of this region. Once the cold anomalies are established over the tropical Atlantic, it persists up to the following summer leading to an anomalous zonal wave-train further inducing a descending branch over NE-India resulting in weak summer monsoon rainfall.

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“…A series of papers from the late 1990s (Cohen and Entekhabi 1999;Cohen et al 2001;Saito et al 2001) introduced the idea that year-to-year variations in October Eurasian snow cover lead to variations in the structure and strength of the Siberian High, that these variations lead to changes in the wave activity flux entering the stratosphere during the winter season, and that these fluxes are responsible for significant variations in the strength of the stratospheric polar vortex (see discussion in ). There has been some debate in the literature about the significance of these precursors (see Limpasuvan et al 2004;Cohen et al 2005;Limpasuvan et al 2005b).…”

Section: Introductionmentioning

confidence: 99%

Observed and simulated precursors of stratospheric polar vortex anomalies in the Northern Hemisphere

Kolstad

Charlton‐Perez

2010

Clim Dyn

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The Northern Hemisphere stratospheric polar vortex is linked to surface weather. After Stratospheric Sudden Warmings in winter, the tropospheric circulation is often nudged towards the negative phase of the Northern Annular Mode (NAM) and the North Atlantic Oscillation (NAO). A strong stratospheric vortex is often associated with subsequent positive NAM/NAO conditions. For stratosphere-troposphere associations to be useful for forecasting purposes it is crucial that changes to the stratospheric vortex can be understood and predicted. Recent studies have proposed that there exist tropospheric precursors to anomalous vortex events in the stratosphere and that these precursors may be understood by considering the relationship between stationary wave patterns and regional variability. Another important factor is the extent to which the inherent variability of the stratosphere in an atmospheric model influences its ability to simulate stratosphere-troposphere links. Here we examine the lower stratosphere variability in 300-year pre-industrial control integrations from 13 coupled climate models. We show that robust precursors to stratospheric polar vortex anomalies are evident across the multi-model ensemble. The most significant tropospheric component of these precursors consists of a height anomaly dipole across northern Eurasia and large anomalies in upward stationary wave fluxes in the lower stratosphere over the continent. The strength of the stratospheric variability in the models was found to depend on the variability of the upward stationary wave fluxes and the amplitude of the stationary waves.

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Evolution of Atmospheric Response to Early-Season Eurasian Snow Cover Anomalies

Cited by 92 publications

References 59 publications

Variability of the Northern Hemisphere polar stratospheric cloud potential: the role of North Pacific disturbances

Variability of the Northern Hemisphere polar stratospheric cloud potential: the role of North Pacific disturbances

Summer monsoon rainfall variability over North East regions of India and its association with Eurasian snow, Atlantic Sea Surface temperature and Arctic Oscillation

Observed and simulated precursors of stratospheric polar vortex anomalies in the Northern Hemisphere

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