A dynamic transition in soil hydrologic states through meteorological variability and terrestrial feedback governs soil-vegetation-climate (SVC) interactions, constrained by critical soil moisture (SM) thresholds. However, observational and scaling constraints limit critical SM threshold estimation at the remote-sensing (RS) footprint scale. Using global surface SM (θ_RS) from NASA’s Soil Moisture Active Passive (SMAP) satellite, we characterize the seasonal preferential hydrologic states of θ_RS and derive three tipping characteristics to estimate the intensity (Mean Tipping Depth, $\bar{\mathit{\epsilon }}$), frequency (Tipping Count, η), and duration (Mean Tipped Time, $\bar{\mathit{\tau }}$) of the excursion of θ_RS from wet- to dry-average conditions. The preferential state provides the seasonally dominant hydrological states of θ_RS, while tipping characteristics capture the ecosystem linkages of the dynamic transition in θ_RS hydrologic states. Globally, θ_RS predominantly exhibits a (unimodal) dry-preferential state, especially over arid/semi-arid drylands and a unimodal wet-preferential θ_RS state in high-latitude boreal forests and tundra biomes. Prevalence of (bimodal) bistable θ_RS state overlaps with regions of strong positive SM-precipitation coupling and monsoonal climate in semi-arid/subhumid climates. Seasonal preferential hydrologic states co-vary with the regional variability in plant water stress threshold and land-atmospheric coupling strength. Tipping characteristics of θ_RS show sensitivity to intra-biome variability in SVC coexistence patterns and display high skill in partitioning global ecoregions. While $\bar{\mathit{\epsilon }}$ and η are climate-controlled, $\bar{\mathit{\tau }}$ is moderated by soil and vegetation through their influence over θ_RS drydown during water-limited evapotranspiration. Preferential states and tipping characteristics find applications in quantifying SVC coexistence patterns, climate model diagnosis, and assessing ecosystem sensitivity to climate change.

中文翻译：

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全球表层土壤水分的优先水文状态及倾倒特征

土壤水文状态通过气象变化和陆地反馈的动态转变控制着土壤-植被-气候（SVC）相互作用，并受到临界土壤湿度（SM）阈值的约束。然而，观测和尺度限制限制了遥感 (RS) 足迹尺度上的关键 SM 阈值估计。使用来自 NASA 土壤湿度主动被动 (SMAP) 卫星的全球表面 SM ( θ _RS )，我们描述了θ _RS的季节性优先水文状态，并推导出三个倾翻特征来估计强度（平均倾翻深度、$\bar{\mathit{\epsilon }}$）、频率（倾倒次数，η）和持续时间（平均倾倒时间，$\bar{\mathit{\tau }}$) θ _RS从湿平均条件到干平均条件的偏移。优先状态提供了θ _RS的季节性主导水文状态，而倾倒特征捕获了θ _RS水文状态动态转变的生态系统联系。在全球范围内，θ _RS主要表现出（单峰）干旱优先状态，特别是在干旱/半干旱旱地，而在高纬度北方森林和苔原生物群落中则表现出单峰湿优先θ _RS状态。 （双峰）双稳态θ _RS状态的普遍性与半干旱/半湿润气候中强正 SM 降水耦合和季风气候的区域重叠。季节优先水文状态与植物水分胁迫阈值和陆地-大气耦合强度的区域变化共同变化。θ _RS的倾斜特征显示出对 SVC 共存模式中生物群落内变异的敏感性，并显示出划分全球生态区域的高技能。尽管$\bar{\mathit{\epsilon }}$和η是气候控制的，$\bar{\mathit{\tau }}$在水限制蒸散过程中，土壤和植被通过影响θ _RS干涸来调节。优先状态和倾倒特征可应用于量化 SVC 共存模式、气候模型诊断和评估生态系统对气候变化的敏感性。