A key process of the nonstationary relationship between ENSO and the Western Pacific teleconnection pattern

Abstract

Recent studies have discovered an intriguing nonstationary relationship between El Ninõ–Southern Oscillation (ENSO) and the Western Pacific (WP) teleconnection pattern, one of the most prominent winter atmospheric circulation patterns in the North Pacific, with a regime-dependent interdecadal modulation of significant and insignificant correlations. However, the physical process underlying the observed nonstationary ENSO-WP relationship is a puzzle and remains to be elucidated, which is also essential for clarifying the still-debated nontrivial issue on whether the WP is directly forced by ENSO or by midlatitude storm tracks-driven intrinsic processes. Based on empirical orthogonal function (EOF) analysis of the upper-tropospheric teleconnection patterns and associated Rossby wave sources (RWS), we show that the nonstationarity in question is due to the regime-dependent constructive or destructive interference in meridional overturning circulation between the two leading EOFs of RWS best correlated with ENSO and WP, respectively. The observed insignificant correlation between ENSO and the WP after the 1988 regime shift can be explained by interrupted teleconnection between the tropics and high latitudes due to the collapse of the subtropical bridge pillar in the jet entrance region, consequence of the destructive interference. This suggested interference mechanism related to the regime-dependent upper-level RWS fields has significant implications for resolving the puzzle that hinders better understanding of decadal regime behaviors of the climate system in the North Pacific.

Atmospheric response to the North Pacific hotspot in idealized simulations: Application to explosive and binary cyclogenesis

“…Positive GPH deviations at about 50 N, 150 W are associated partly with the negatively intensified Rossby wave source (RWS) at 200 hPa (Figure 2c) via the enhanced divergence of Ferrel circulation around 60 N, which differs from the CNTL (Figure S1b). The negative RWS over the North Pacific (Shimizu and Cavalcanti, 2011;Park et al, 2018) is induced by upper-level divergence associated with the eddy-driven indirect circulation, which is regionally enhanced (Figure 1c) due to the hotspot. Park 2018) discussed the modification of the RWS through horizontal divergence of regional meridional circulation in the nonstationary relationship between El Nino-southern oscillation and the Western Pacific teleconnection.…”

“…Park et al . (2018) discussed the modification of the RWS through horizontal divergence of regional meridional circulation in the nonstationary relationship between El Nino‐southern oscillation and the Western Pacific teleconnection. In contrast, the present work suggests a stationary relationship between the oceanic hotspot and the upper‐level RWS owing to storm‐track (eddy)‐driven meridional circulation.…”

Holocene Ecohydrological Variability on the East Coast of Kamchatka

“…In addition to the Aleutian Low and North Pacific High, the major control on modern climate in the Pacific is the El Niño-Southern Oscillation (ENSO). The conditions in the tropical Pacific can influence storm tracks and other climatological parameters at higher latitudes (Park et al, 2018). To understand this connection, we compare our records of climate, vegetation and carbon accumulation from Newmarket Fen with the Holocene record of the SST gradient across the tropical Pacific (Figure 5).…”

“…During the middle Holocene, centering on about 6 ka, when conditions at Newmarket are driest and δD prc is most depleted, the SST gradient across the tropical Pacific is steepest, with the warmest west Pacific and coolest eastern Pacific (Koutavas and Joanides, 2012). Such conditions today are associated with an expanded tropical wind belt and contracted northern hemisphere jets (Park et al, 2018). Shifted storm tracks can reduce the amount of moisture received at Newmarket Fen, as flow can become more zonal (Honda et al, 1999;Rodionov et al, 2007;Mesquita et al, 2016).…”

Tropospheric Water Vapor Long‐term Periodicities and ENSO Relation in European Territory of Russia

“…The Space-time complexity of ENSO results in potentially different remote teleconnection patterns and corresponding weather and climate impacts on different Earth regions (López-Parages et al, 2016;Park et al, 2018;Timmermann et al, 2018). El Niño has a significant impact on the dynamics of the atmosphere of middle and high latitudes (Geng et al, 2018;Llamedo et al, 2017).…”