**4. Discussion**

Snow disasters are one of the most important meteorological hazards on the QTP, and their spatial and temporal characteristics and influencing factors have received more and more attention in recent years; however, some findings are constrained by the plateau's poor distribution of meteorological stations. In this paper, we used remote sensing data to analyze the spatial and temporal occurrence patterns of snow disasters on the QTP. Results demonstrated that, during the past 40 years, the frequency, duration, average snow depth, and grade of snow disaster on the QTP have all exhibited significant interannual and interdecadal variabilities, as well as a declining long-term trend, which is consistent with some previous studies [4,11,12,19]. In addition to the direct influence of local climatic conditions [12], many circulation factors also modulate the occurrence of snow disasters on the QTP through westerly winds and atmospheric bridges. These factors all contribute to the variability of snow disasters on interannual to interdecadal time scales. Huang et al. [36] suggested that snow disasters were more likely to occur when the west wind belt and the polar vortex in the eastern hemisphere are stronger and the East Asian trough and subtropical high are more westerly, and vice versa. SST, as an important external forcing factor, also profoundly affects the occurrence of snow disasters, and the equatorial central-east Pacific, the tropical Indian Ocean, and the North Atlantic are some of the more critically affected areas [14,37–39]. In addition, the positive North Atlantic Oscillation (NAO) can excite Rossby waves, which can strengthen the Indo–Myanmar trough on the southern side of the plateau and promote snowfall on the QTP, leading to more snow disasters [40,41]. Furthermore, Arctic sea ice, as an important external forcing factor affecting extreme weather and climate events at medium latitudes [42], also has an important modulating effect on the occurrence of snow disasters on the Tibetan plateau. A positive anomaly of Arctic sea ice can enhance the meridional temperature gradient, which excites upward-propagating and equatorward-propagating anomalous Rossby waves, leading to an anomalous dipole pattern of atmospheric circulation over the polar regions and Eurasia, enhancing the zonal advection and meridional convergence of atmospheric moisture fluxes over the plateau and favoring snow disasters [43,44]. Other circulation factors, such as El Niño (ENSO) and the Arctic Oscillation (AO), can also influence the occurrence of snow disasters through cyclonic circulation propagating along the westerly wind belt [14,37,45,46]. We also discussed the possible influences of snow disasters on the farmer and pastoralist well-being (FPWB) since the 21st century. Since World War II, with the ensuing economic development, academics, decision-makers, and practitioners around the world have paid close attention to human well-being, and gross domestic product (GDP) was once the dominant measure of human well-being [47,48]. However, since GDP is mainly a reflection of economic indicators, it is hoped that other factors, such as social, humanistic, and ecological factors, can be absorbed into the human well-being evaluation system. The Millennium Ecosystem Assessment [49] provides a useful framework for the study of ecosystem services as an influencing factor on human well-being, making explicit the close relationship between ecosystem services and human well-being and ushering in a new era of human well-being research. Within this framework, a large number of studies revealed the characteristics of changes in human well-being in different regions and at different time scales, as well as their main drivers [50–53]. However, current research on human well-being tends to be a holistic concept, and there is no uniform definition of the meaning of well-being for different groups of people. Farmers and pastoralists are the majority of the inhabitants of the QTP, and it is of grea<sup>t</sup> practical importance to discuss their well-being to improve the well-being of the plateau people. Generally, farmers' happiness increases with job satisfaction and income, while land as an important means of production for farmers is closely related to farmers' income [54], and the stronger the farmers' willingness to retire from farming, the worse their happiness is [55]; moreover, farmers' self-rated health status has a positive impact on their well-being [56]. Here, the FPWB index on the QTP was established by combining the sources of income, living styles, and economic factors, and exploring the impact of snow disasters on the well-being of

farmers and pastoralists. The results (Figure 10 and Table 5) show that snow disasters have a certain negative impact on the FPWB, but we only discussed the impact of a single meteorological disaster, and it is necessary to systematically explore the systematic impact of other meteorological disasters on the FPWB in the future. Meanwhile, it should be noted that the improvement of FPWB on the QTP has been stagnant or even declining in recent years. This may be related to the increase of extreme weather and climate events caused by climate change which affect the living environment, life, and property of farmers and pastoralists. On the other hand, the advancement of urbanization on the QTP may attract a large number of young people to work and live in cities, which indirectly leads to the decline of human resources, production level, and production capacity in agriculture and livestock, thus, affecting the overall situation of farmer and pastoralist well-being.
