Land Surfaces at the Tipping‐Point for Water and Energy Balance Coupling

Dong, Jianzhi; Akbar, Ruzbeh; Feldman, Andrew F.; Gianotti, Daniel J. Short; Entekhabi, Dara

doi:10.1029/2022wr032472

Cited by 6 publications

(5 citation statements)

References 77 publications

(120 reference statements)

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“…Dirmeyer et al., 2021). In addition, WP of vegetation can sometimes occur in medium wetness levels of SMC (Dong et al., 2023), so the hypersensitive regime can occur at a relatively wet SMC values over locations such as in the western US, northern Europe, and South China (Figure 2) that is consistent with Ni et al. (2024).…”

Section: Hypersensitive Regimes Detected From In Situ Observationssupporting

confidence: 82%

Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime

Hsu,

Dirmeyer,

Seo

2024

Water Resources Research

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High temperature extremes accompanied by drought have led to serious ramifications for environmental and socio‐economic systems. Thus, improving the predictability of heat‐wave events is a high priority. One key to achieving this is to better understand land‐atmosphere interactions. Recent studies have documented a hypersensitive regime in the soil moisture‐temperature relationship: when soil dries below a critical low threshold, called the soil moisture breakpoint, air temperatures increase at a greater rate as soil moisture declines. Whether such a hypersensitive regime is rooted in land surface processes and whether this soil moisture breakpoint corresponds to a known plant critical value, the permanent wilting point (WP), below which latent heat flux almost ceases, remains unclear. In this study, we explore the mechanisms linking low soil moisture to high air temperatures. From in situ observations, we confirm that the hypersensitive regime acts throughout the chain of energy processes from land to atmosphere. A simple energy‐balance model indicates that the hypersensitive regime occurs when there is a dramatic drop in evaporative cooling, which happens when soil moisture dries toward the permanent WP, suggesting that the soil moisture breakpoint is slightly above the permanent WP. Precisely how a model represents the relationship between evapotranspiration and soil moisture is found to be essential to describe the occurrence of the hypersensitive regime. Thus, we advocate that weather and climate models should ensure a realistic representation of land‐atmosphere interactions to obtain reliable forecasts of extremes and climate projections, aiding the assessment of heatwave vulnerability and adaptation.

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Section: Hypersensitive Regimes Detected From In Situ Observationssupporting

confidence: 82%

Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime

Hsu,

Dirmeyer,

Seo

2024

Water Resources Research

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“…Such positive feedback typically occurs in semiarid and arid regions, where latent heat flux is largely limited by soil water availability (Seneviratne et al 2010, Hsu andDirmeyer 2023). The YZB is a typical energylimited region (Dong et al 2023) with annual mean precipitation exceeding 800 mm (Gao et al 2020). Due to relatively sufficient soil water storage, the heatwave in 2022 July was mitigated to some extent by the increasing latent heat (figure 2(g)).…”

Section: Discussionmentioning

confidence: 99%

“…On the one hand, high temperature dries the soil by increasing evaporation and plant transpiration (Gentine et al 2019. On the other hand, drier soil intensifies surface warming through a decrease in latent heat flux and an increase in sensible heat flux, leading to higher surface temperature and lower atmospheric humidity (Dong et al 2022(Dong et al , 2023. For example, soil moisture-temperature coupling contributed 50.6% to extreme temperatures over western North America in summer 2021 (Zhang et al 2023b).…”

Section: Introductionmentioning

confidence: 99%

Shift of soil moisture-temperature coupling exacerbated 2022 compound hot-dry event in eastern China

Ni,

Qiu,

Miao

et al. 2024

Environ. Res. Lett.

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Compound hot-dry events (CHDEs) are among the deadliest climate hazards and are occurring with increasing frequency under global warming. The Yangtze River Basin in China experienced a record-breaking CHDE in the summer of 2022, causing severe damage to human societies and ecosystems. Recent studies have emphasized the role of atmospheric circulation anomalies in driving this event. However, the contribution of land–atmosphere feedback to the development of this event remains unclear. Here, we investigated the impacts of soil moisture-temperature coupling on the development of this concurrent heatwave and drought. We showed that large amounts of surface net radiation were partitioned to sensible heat instead of latent heat as the soil moisture-temperature coupling pattern shifted from energy-limited to water-limited under low soil moisture conditions, forming positive land–atmosphere feedback and leading to unprecedented hot extremes in August. The spatial heterogeneity of hot extremes was also largely modulated by the land–atmosphere coupling strength. Furthermore, enhanced land–atmosphere feedback has played an important role in intensifying CHDEs in this traditional humid region. This study improves the understanding of the development of CHDEs from three aspects, including timing, intensity, and spatial distribution, and enables more effective early warning of CHDEs.

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“…Evapotranspiration represents a significant pathway for soil moisture entering the atmospheric system, thereby linking physical processes such as the land surface water cycle, energy balance, and carbon balance. Quantifying the stress effect of soil moisture on evapotranspiration is a key process, and it is difficult to estimate surface evapotranspiration [36]. The third most studied is drought, which not only affects the carbon, nitrogen, and water cycles of ecosystems but also has an impact on socioeconomic development and people's production and livelihoods, and even causes huge losses.…”

Section: Hot Topics and Frontiersmentioning

confidence: 99%

Analysis of Hotspots and Trends in Soil Moisture Research since the 21st Century

Cai,

Yang,

Yue

et al. 2023

Atmosphere

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Soil moisture is a key factor in ecosystems that profoundly affects carbon, nitrogen, and water cycles on land surfaces, vegetation growth, and climate change. Consequently, numerous scholars have researched and authored scientific literature on soil moisture and related topics. Using the Web of Science database, we conducted a bibliometric analysis of 60,581 papers published in the field of soil moisture between 2000 and 2022. The findings revealed the following trends. (1) The number of publications on soil moisture has consistently increased in the 21st century at an increasing rate. For instance, although the annual increase was only 94 publications in 2005, it surged to 321 publications in 2020. (2) The United States (US), China, and developed European countries emerged as primary research institutions and authors. The US occupies a leading position in soil moisture research, boasting the highest number of publications and total citations in the field, whereas China ranks second in both publications and total citations. (3) Regarding international collaboration, the US has established close partnerships with numerous international research institutions. However, China’s international cooperation in this field requires improvement. (4) The Journal of Hydrology holds the top position in terms of both the total number of published articles and citations. Research on water resources ranked first in terms of its H-index. (5) Keyword analysis highlighted several current research hotspots, including the coupled covariance effect of soil moisture and land surface environmental factors in the context of climate change, soil moisture utilization rate, crop yield, influence mechanism of soil moisture on soil ecosystem structure, and development of high-precision soil moisture data products. In conclusion, this study provides a systematic review of the research hotspots and trends in soil moisture studies in the 21st century. The objective is to offer a comprehensive reference to aid in understanding the evolutionary patterns of soil moisture research in multiple dimensions.

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Land Surfaces at the Tipping‐Point for Water and Energy Balance Coupling

Abstract: During drydowns and depending on the availability of volumetric soil moisture ( 𝐴𝐴 𝐴𝐴 ), microclimate and landscape attributes, evaporation can be classified to be in energy-(Stage-I) or water-limited (Stage-II) regimes (

Cited by 6 publications

References 77 publications

Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime

Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime

Shift of soil moisture-temperature coupling exacerbated 2022 compound hot-dry event in eastern China

Analysis of Hotspots and Trends in Soil Moisture Research since the 21st Century

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