An Interdecadal Change in the Influence of ENSO on the Spring Tibetan Plateau Snow-Cover Variability in the Early 2000s

Abstract

El Niño–Southern Oscillation (ENSO) and the Tibetan Plateau snow cover are important factors in interannual climate variability. The relationship between ENSO and the Tibetan Plateau snow variation is still an issue unresolved. While some studies suggested that ENSO is a key factor of changes in snow cover over the Tibetan Plateau, other studies noted independence between the two. The present study revealed a prominent interdecadal change in the relationship between ENSO and the spring Tibetan Plateau snow cover variation in the early 2000s. There is a significant positive correlation between ENSO and the spring Tibetan Plateau snow cover variation in the period 1988-2003, but an obvious negative relationship is detected in the period 2004-2019. The interdecadal change in the ENSO-snow relationship is related to the distinct pathway of ENSO influence on the spring Tibetan Plateau snow cover variation during the two periods. In the period 1988-2003, ENSO induces anomalous convection over the tropical western North Pacific that in turn cause atmospheric circulation and moisture anomalies over the Tibetan Plateau. The resultant winter snow anomalies over the central-eastern Tibetan Plateau persist to the following spring. In the period 2004-2019, ENSO induces North Atlantic sea surface temperature (SST) anomalies in winter that are maintained to the following spring. The North Atlantic SST anomalies then stimulate the atmospheric circulation anomalies extending to the Tibetan Plateau that induce snow cover anomalies there in spring. The different processes of ENSO influence lead to opposite anomalies of spring snow cover over the Tibetan Plateau in the two periods.

What Controls the Subseasonal Precipitation Reversal Over the Western Tibetan Plateau in Winter?

“…In December, the zonally propagating Rossby wave over the mid‐high latitudes stimulates the alternating positive and negative geopotential height anomalies, resulting in the anomalous anticyclonic circulation over the WTP (Figure 2a). The anomalous easterlies to the south of the anticyclone could weaken the subtropical westerlies and retard moisture transport (Figure 3b), as shown in previous studies (Sun et al., 2020; Yuan et al., 2023). While in JF, the propagating Rossby wave emanating from Scandinavia dominates Eurasia, resulting in distinct negative geopotential height anomalies over the northwest of the TP and strengthening the Middle East jet stream (Figures 2b and 3c).…”

The Influence of Solar Activity on Snow Cover over the Qinghai–Tibet Plateau and Its Mechanism Analysis

“…The SRF time series exhibits an obvious 11-year cycle with alternating peak and valley SA years (Figure 2). When considering the impact of SA on snow cover on the QTP, the effects of ENSO and volcano eruption must be excluded because they are strong interannual signals that cause climate anomalies and ENSO has a distinct interdecadal variation, which could induce anomalous snow cover on the QTP [54]. Therefore, the peak years of SRF selected, excluding the impact of strong ENSO events (i.e., strong El Niño and La Niña events) and volcano eruption, were 1957/1958, 1967/1968, 1979/1980, 1990/1991, and 2001/2002; while the valley years were 1963/1964, 1975/1976, 1986/1987, 1995/1996, and 2008/2009, respectively.…”

On the Relevance of Aerosols to Snow Cover Variability Over High Mountain Asia

“…Recent studies have attributed this decline to atmospheric teleconnections (e.g., Wang et al., 2021), solar radiation, temperature, precipitation, and their seasonal fluctuations (e.g., Bhattacharya et al., 2021; Johnson & Rupper, 2020; Sahu & Gupta, 2020 and references therein). In addition, there are topographic controls on SC variability and associated runoff due to HMA's steep and complex terrain (Gurung et al., 2017; Jain et al., 2009; She et al., 2015).…”

“…Snow cover (SC) and its extent is a widely used parameter to characterize the spatiotemporal distribution of these glaciers since it serves as a conduit between surface processes and the atmosphere over it. In fact, observational studies (Notarnicola, 2020) and future projections (Lalande et al, 2021) report that approximately 86% of HMA areal extent exhibit negative trends in SC due to climate change.Recent studies have attributed this decline to atmospheric teleconnections (e.g., Wang et al, 2021), solar radiation, temperature, precipitation, and their seasonal fluctuations (e.g., Bhattacharya et al, 2021;Johnson & Rupper, 2020; Sahu & Gupta, 2020 and references therein). In addition, there are topographic controls on SC variability and associated runoff due to HMA's steep and complex terrain (Gurung et al, 2017;Jain et al, 2009;She et al, 2015).…”