Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime
Abstract 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...
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Wiley
2024-07-01
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| Series: | Water Resources Research |
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| Online Access: | https://doi.org/10.1029/2023WR036490 |
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| author | Hsin Hsu Paul A. Dirmeyer Eunkyo Seo |
| author_facet | Hsin Hsu Paul A. Dirmeyer Eunkyo Seo |
| author_sort | Hsin Hsu |
| collection | DOAJ |
| description | Abstract 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. |
| format | Article |
| id | doaj-art-00c711ac743f48c8ac7fe7cc557cb0bc |
| institution | Kabale University |
| issn | 0043-1397 1944-7973 |
| language | English |
| publishDate | 2024-07-01 |
| publisher | Wiley |
| record_format | Article |
| series | Water Resources Research |
| spelling | doaj-art-00c711ac743f48c8ac7fe7cc557cb0bc2025-08-20T03:30:56ZengWileyWater Resources Research0043-13971944-79732024-07-01607n/an/a10.1029/2023WR036490Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling RegimeHsin Hsu0Paul A. Dirmeyer1Eunkyo Seo2Princeton University Princeton NJ USAGeorge Mason University Fairfax VA USACenter for Ocean‐Land‐Atmosphere Studies George Mason University Fairfax VA USAAbstract 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.https://doi.org/10.1029/2023WR036490heat extremesland‐atmosphere interactions |
| spellingShingle | Hsin Hsu Paul A. Dirmeyer Eunkyo Seo Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime Water Resources Research heat extremes land‐atmosphere interactions |
| title | Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime |
| title_full | Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime |
| title_fullStr | Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime |
| title_full_unstemmed | Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime |
| title_short | Exploring the Mechanisms of the Soil Moisture‐Air Temperature Hypersensitive Coupling Regime |
| title_sort | exploring the mechanisms of the soil moisture air temperature hypersensitive coupling regime |
| topic | heat extremes land‐atmosphere interactions |
| url | https://doi.org/10.1029/2023WR036490 |
| work_keys_str_mv | AT hsinhsu exploringthemechanismsofthesoilmoistureairtemperaturehypersensitivecouplingregime AT pauladirmeyer exploringthemechanismsofthesoilmoistureairtemperaturehypersensitivecouplingregime AT eunkyoseo exploringthemechanismsofthesoilmoistureairtemperaturehypersensitivecouplingregime |