Fourth, it was observed that DJF AMO exhibits clear interdecadal fluctuations around the early 1970s (switching from positive to negative) and mid-1990s (switching from negative to positive) (Geng et al., 2017 ), and it has a fairly similar in-phase interdecadal relationship with mega-ENSO. , 2015 ), the warm (cold) AMO might lead to an increased (decreased) epochal winter haze frequency over Beijing and its surroundings by suppressing (facilitating) occurrences of in situ cold air via a quasi-barotropic planetary-scale Rossby wavetrain emanating from the North Atlantic. However, the actual decreased epochal WHDBlowjob during P2 (corresponding to warm AMO) and increased epochal WHDCock sucking during P1 (corresponding to cold AMO) allow us to speculate that AMO could play a relatively minor role in modulating WHDBj on decadal timescales compared to mega-ENSO. Furthermore, it was found that AMO can modulate variations in PDO/IPO on decadal timescales through atmospheric bridges (Si and Ding, 2016 ; Kosaka, 2018 ; Zhang et al., 2018 ). Therefore, the existence of appreciable interactions between DJF AMO and mega-ENSO, if any, should be ascertained. These issues are deserving of further investigations in future studies.
ACKNOWLEDGEMENTS
We’re thankful so you can Zhiwei Zhu and Jian Cao regarding Nanjing University of data Technology and you can Technical getting useful talk and you can technical advice in running the fresh new mathematical design. We thank new unknown reviewers because of their positive comments and you can guidance. So it work is backed by the new Atmospheric Contamination Command over the Primary Minister Fund (Give Zero. DQGG0104), the latest Federal Absolute Science First step toward Asia (Offer No.41790471), this new National Preliminary research Creativity (973) program from China (Give Zero. 2012CB417205), additionally the Proper Top priority Search System of Chinese Academy off Sciences (Offer Zero.
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Analysis S1 Figure S1. December–March (DJF) compound distinctions regarding sea facial skin heat (SST) (shaded, °C) into the months anywhere between (a) pre-P1 (1961–1971) and you may P1 (1972–1996) (pre-P1 minus P1) and you can (b) P2 (1997–2012) and you may blog post-P2 (2013–2018) (P2 minus post-P2) just after removing this new linear pattern. The newest purple traces in (a) and you may (b) inform you brand new west Pacific K-shape together with east Pacific triangle-profile countries, which can be implemented in defining the super-ENSO index centered on Wang mais aussi al. (2013).
Figure S2. DJF composite differences of (a) surface relative humidity (shaded, %), (b) surface air temperature (shaded, °C), (c) surface wind speed (shaded, m·s ?1 ), (d) sea-level pressure (shaded, hPa), (e) planetary boundary layer height (shaded, m), and (f) air temperature between 850 and 1,000 hPa (shaded, °C) between years of more and less frequent wintertime haze days in Beijing (WHDBj). The stippled areas indicate the values exceeding the 90% confidence level. The pentagram delineates the location of Beijing. The more (less) frequent WHDBlowjob is defined with a detrended WHDBj value >0.8 (
Shape S3. The fresh new climatological-imply (1981–2010) DJF five-hundred-hPa geopotential top (traces, gpm) and 850-hPa wind (vectors, m·s ?step 1 ). The pentagram spells out the region out-of Beijing, as well as the grey shaded area indicates the new Tibetan Plateau.
Shape S4posited DJF anomalies regarding (a) skin cousin humidity (shady, %), (b) epidermis sky temperatures (shady, °C), (c) epidermis wind speed (shady, m·s ?1 ), (d) sea-peak tension (shaded, hPa), and you will (e) heavens temperatures between 850 and you may step 1,000 hPa (shaded, °C) to possess pre-P1 (1961–1971). The bottom several months is actually 1961–2018.
Contour S5. DJF chemical variation off five-hundred-hPa omega (traces, ten ?dos Pa·s ?step one ) for the period ranging from P1 (1972–1996) and you may P2 (1997–2012) (P2 without P1) immediately after deleting the newest linear pattern. Values that will be high on 90% confidence top try shady. This new pentagram delineates the spot regarding Beijing.
Profile S6posited DJF anomalies out-of SST (shady, °C) getting post-P2 (2013–2018). The fresh new purple lines tell you new western Pacific K-contour additionally the eastern Pacific triangle-shape nations, being implemented inside the identifying the brand new super-ENSO index based on Wang mais aussi three day rule al. (2013). The bottom months is actually 1961–2018.