As Earth System Models (ESMs) move toward kilometer-scale grid spacing, resolving small-scale atmospheric processes substantially improves the representation of convection and precipitation. However, the land component remains a major source of uncertainty in the atmospheric water cycle. Inadequate soil moisture and groundwater representations affect evaporation, land–atmosphere coupling, and ultimately the atmospheric supply of water as precipitation. These hydrological biases therefore influence not only local surface conditions but also remote moisture transport and recycling. In this work, we improve the representation of subsurface hydrology in the JSBACH land surface model, coupled to the ICON atmospheric model. We introduce additional soil layers, implement lateral groundwater flow between grid cells, and connect shallow groundwater to the river network. We evaluate the new developments using standalone kilometer-scale JSBACH simulations against flux tower measurements of latent and sensible heat fluxes and soil moisture observations in the Pyrenees (Spain and France). We then assess their impact on atmospheric variables, specifically 2 m temperature and precipitation, within ICON simulations at 3-km grid spacing over Europe.

How to cite: Lalonde, M. and Prein, A. F.: Atmospheric Feedbacks to Improved Subsurface Hydrology in a km-Scale Earth System Model (ICON–JSBACH), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2115, https://doi.org/10.5194/egusphere-egu26-2115, 2026.

The Northern Sandy Belt, a key ecological barrier and fragile zone in China, has its regional sustainable development determined by the coordination status of its water and soil resources system. This study takes the Horqin-Hunshandake Sandy Area as the research object. Based on data from 2006 to 2022, we established an adaptive evaluation system consisting of 18 indicators, and combined the coupling coordination degree model with Tobit regression to reveal the evolutionary characteristics and influencing mechanisms of the system’s coupling coordination. The results show that:(1) During the study period, the coupling coordination degree showed a fluctuating upward trend, rising from 0.367 in 2009 to 0.602 in 2021. The coordination status shifted from mild imbalance to basic coordination, but its stability was insufficient, with significant declines in 2017, 2019, and 2022;(2) There was significant spatial differentiation: Tongliao City had the highest and most stable coordination level, while Hinggan League had the lowest, and Xilingol League experienced the most drastic fluctuations. Regional differences are closely linked to the natural background and socio-economic patterns;(3) The system development exhibited phased transitions: the water resources system dominated from 2006 to 2014, while the contribution of the land resources system increased from 2015 to 2022;(4) Annual precipitation had a significant positive promoting effect on the coupling coordination degree, while annual water consumption had a significant negative inhibiting effect; population pressure indirectly affected the system balance through resource demand.

This study indicates that water resources are the core constraint for the development of the Northern Sandy Belt, and exceeding the carrying capacity will lead to system imbalance. For future development, it is necessary to adhere to the principle of "determining land use and production based on water availability", strengthen rigid constraints on water resources, implement differentiated management, and build a monitoring and early warning system to achieve sustainable development. This study provides a scientific basis for the optimal allocation of regional water and soil resources and ecological management.

How to cite: Wang, K.: Research on the Coupling Coordination Degree andInfluencing Mechanisms of the Water and Soil ResourcesSystem in the Northern Sandy Belt, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9803, https://doi.org/10.5194/egusphere-egu26-9803, 2026.

Pan evaporation (Epan) is widely used as an indicator of atmospheric evaporative demand and plays an important role in understanding land-atmosphere interactions under climate variability. However, observed changes in Epan do not always follow the expected increase with rising temperature, a phenomenon known as the pan-evaporation paradox. The relative influence of climatological drivers on Epan remains particularly uncertain in humid equatorial regions, where high moisture availability may alter the controls on evaporation. This study examines pan evaporation and associated climatological variables in Riau Island, Indonesia. Temporal trends are assessed using the Trend-Free Pre-Whitening Mann–Kendall test, while Spearman correlation analysis is applied to evaluate the relationships between Epan and key climatic factors, including solar radiation duration, relative humidity, precipitation, wind speed, and air temperature. The results show that correlation analysis indicates that Epan is strongly and positively associated with solar radiation duration and negatively associated with relative humidity and precipitation. Wind speed shows a moderate positive relationship with Epan, while temperature variables exhibit weaker associations. Trend analysis further shows that minimum temperature exhibits a statistically significant increasing trend, whereas wind speed displays a statistically significant declining trend. In contrast, pan evaporation does not exhibit a statistically significant long-term trend. Overall, the findings suggest that pan evaporation variability in humid equatorial climates is primarily governed by radiative and moisture-related controls rather than temperature alone. The opposing effects of increasing temperature and declining wind speed likely contribute to the statistically insignificant long-term trend in pan evaporation observed, providing observational insight into evaporation dynamics under humid tropical conditions.

How to cite: Parhusip, M. A., Permatasari, M. P., and Chen, S.-T.: Climatological Drivers of Pan Evaporation in the Riau Islands, Indonesia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10910, https://doi.org/10.5194/egusphere-egu26-10910, 2026.

Atmospheric dryness, often quantified by Vapor Pressure Deficit (VPD) or Relative Humidity (RH), is a prominent variable for terrestrial water and carbon cycles. While global warming is widely expected to amplify atmospheric dryness, the physical drivers governing this intensification and its regional variations remain poorly understood. Here we analytically decompose trends in daily maximum VPD and minimum RH into contributions from three key factors: the Clausius-Clapeyron temperature sensitivity of saturation vapor pressure, the diurnal temperature range (reflecting daily heat storage changes in lower atmosphere), and the proximity to saturation of the atmosphere at night (defined as the difference between minimum temperature and the dew point). Applying this framework to long-term observations from FLUXNET and ERA5 reanalysis reveals that Clausius-Clapeyron scaling is the dominant driver of global atmospheric drying trends. In addition, we find that regional variations in drying trends between arid and humid regions primarily come from contrasting trends in nighttime atmospheric dryness. This regionally asymmetric response amplifies dryness trends in arid regions while dampens it in humid regions, aligning with the "dry-gets-drier, wet-gets-wetter" paradigm under future climate change. Our analytical framework helps explain observed spatial heterogeneity in atmospheric drying trends and also offers a new pathway for evaluating its representations in climate models.

How to cite: Chauhan, T. A., Ghausi, S. A., and Kleidon, A.: Global trends in atmospheric dryness dominated by Clausius-Clapeyron scaling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6959, https://doi.org/10.5194/egusphere-egu26-6959, 2026.

Extreme precipitation associated with landfalling tropical cyclones poses major forecasting challenges, particularly over complex terrain. This study investigates the sensitivity of simulated hurricane rainfall to microphysics parameterization and horizontal resolution using the Weather Research and Forecasting (WRF) model for Hurricane Melissa, a Category 5 storm that made historic landfall over Jamaica in October 2025 and produced rainfall exceeding 1,000 mm in mountainous regions. Four WRF simulations were conducted using two commonly applied microphysics schemes, WSM6 (single-moment) and Morrison (double-moment), across two domain configurations: a single 9 km grid covering the Caribbean basin and a nested configuration with a 3 km convection-permitting inner domain centered over Jamaica. Model outputs were evaluated against satellite-based precipitation estimates from IMERG and CHIRPS. Results suggest that horizontal resolution strongly controls the spatial pattern of simulated precipitation. The 3 km nested simulations capture sharper gradients, localized maxima, and more physically consistent rainfall structures compared to the smoother and more diffuse patterns produced at 9 km resolution. Differences between microphysics schemes are secondary to resolution but remain evident, with the Morrison scheme producing more coherent and structured precipitation fields, while WSM6 generates more fragmented and spatially patchy rainfall. All simulations accurately reproduce the timing of peak precipitation during landfall, indicating weak sensitivity of storm evolution to microphysics choice. However, total rainfall amounts vary substantially across configurations, with convection-permitting simulations producing significantly higher accumulations. These totals exceed CHIRPS estimates, likely due to the underestimation tendency of extreme precipitation in complex terrain by CHIRPS, while agreement with IMERG varies by location and intensity. These findings highlight that accurate representation of extreme tropical cyclone precipitation requires convection-permitting resolution, while rainfall intensity remains sensitive to both microphysics selection and observational reference datasets.

How to cite: Muna, T. S., Miller, P. W., and Bushra, N.: Sensitivity of Extreme Hurricane Precipitation to WRF Microphysics and Grid Spacing: Hurricane Melissa (2025) Landfall over Jamaica, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15243, https://doi.org/10.5194/egusphere-egu26-15243, 2026.

In the tropics, the land-ocean precipitation partitioning χ is skewed toward land. We analyze how CO₂- and uniform sea surface temperature increase affect this partitioning. To do so, we use 15 years of global simulations conducted with the ICON model at 10 km horizontal grid spacing and explicitly resolved convection, unlike previous studies that parameterized convection. ICON produces a precipitation partitioning that is more consistent with observations compared to the AMIP6 ensemble. Under 4xCO₂, precipitation partitioning toward land increases, whereas it decreases in +4K. We develop a framework based on energy and moisture budgets to decompose the response of the precipitation partitioning into contributions from the land column-integrated atmospheric heating, circulation efficiency, moisture cycling, and tropical radiative cooling. In ICON and the AMIP6 ensemble, the land's column-integrated atmospheric heating is identified as the primary driver of changes in precipitation partitioning. This is a result of the change in land moisture convergence and land precipitation in response to circulation adjustments driven by land-sea asymmetries in atmospheric heating. The response of the controlling factors are similar in ICON and in the AMIP6 ensemble, apart from two qualitative differences. First, the land's circulation efficiency is more stable in ICON than in AMIP6, which we interpret to be due to a stronger coupling of precipitation to surface heat fluxes in AMIP6. Secondly, the opposing response in χ  upon 4xCO₂ and +4K are virtually equal in magnitude in ICON, whereas in AMIP6 χ decreases more in +4K than it increases in 4xCO₂. These findings suggest that coarse-resolution GCMs may overestimate the predicted decrease in land precipitation under global warming.

How to cite: Schulz, M.: The Response of Tropical Land-Ocean Precipitation Partitioning to SST and CO2 increase in Global Storm Resolving Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6701, https://doi.org/10.5194/egusphere-egu26-6701, 2026.

Atmospheric rivers (ARs) efficiently transport moisture from tropical and/or subtropical regions to middle and high latitudes, serving not only as the most important global poleward moisture transport belts but also as one of the primary causes of extreme precipitation and flooding in many parts of the world. Research on ARs in East Asia started relatively late; however, due to the region’s unique climatic characteristics, the manifestations of ARs differ from those in regions such as North America. In recent years, studying the lifecycle characteristics of consecutive AR events has become increasingly important. Nevertheless, on a climatic timescale, the moisture origins and transport processes during consecutive AR events in East Asia remain poorly understood, which is critical for understanding the genesis and sustenance of such events. In this study, the ERA5 reanalysis data from 1980 to 2024 were used to extract a dataset of consecutive AR events that made landfall in East Asia during this period, based on which the basic climatic characteristics of AR lifecycles were analyzed. Furthermore, this research focuses on the moisture sources and transport processes of ARs, employing an extended dynamic moisture recycling model specifically designed for tracking moisture in consecutive ARs to conduct a detailed quantitative analysis of the moisture budget during the lifecycle of ARs affecting East Asia. The findings reveal that ARs impacting East Asia typically originate from the Bay of Bengal to southwestern China and dissipate over the Yangtze–Huai River region, the Korean Peninsula, and Japan. The moisture contributing to ARs in East Asia mainly originates from the Indian Ocean, the Western Pacific, and high-latitude Eurasian regions, with the most significant contributions coming from the Arabian Sea, the Bay of Bengal, the Western Pacific, and terrestrial areas in eastern China. Notably, the moisture contribution from land areas in East Asia, particularly South China, is crucial for sustaining and transporting moisture during the AR lifecycle, highlighting the reliance of consecutive AR events on moisture transport from mid- and even high-latitude regions.

How to cite: Hua, L. and Zhong, L.: Quantitative Analysis of Moisture Budget in the Lifecycle of Consecutive Atmospheric River Events Affecting East Asia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8606, https://doi.org/10.5194/egusphere-egu26-8606, 2026.

The Tibetan Plateau (TP), often termed the “Asian Water Tower”, is a critical reservoir and regulator of the Asian hydrological cycle. In recent decades, summer precipitation over the TP has exhibited a pronounced South Drying-North Wetting dipole pattern, with profound implications for regional water security and ecosystem stability. Both externally advected and internally recycled precipitation may contribute to this pattern. However, their respective roles and the extent to which anthropogenic forcing has shaped their contributions remain unclear. Here, we use the WAM2layers moisture-tracking model to partition TP summer precipitation into externally sourced and internally recycled components, and to quantify how changes in precipitation frequency and intensity shape the dipole. We find that the dipolar pattern is primarily driven by changes in externally sourced precipitation, which strengthens precipitation in the north while inducing drying in the south, with internally recycled precipitation further amplifying southern aridification. Specifically, increases in the frequency of externally sourced precipitation events lead to a plateau-wide precipitation increase. However, this effect is offset over the southern TP by a concurrent decline in event intensity, thereby shaping northward moistening associated with the externally sourced component. Meanwhile, the reduction of internally recycled precipitation in the southern TP is primarily attributable to a decrease in event frequency, while increases in the north result from simultaneous enhancements in both frequency and intensity. Mechanistically, a weakened subtropical westerly jet, due to spatially uneven emissions of anthropogenic aerosols, strengthens the dipole by enhancing externally sourced precipitation intensity over the northern plateau while suppressing it in the south. By contrast, negative phases of the Interdecadal Pacific Oscillation mainly reduce the frequency of internally recycled precipitation in the south. These findings reveal that anthropogenic forcing and natural variability jointly shape the TP summer precipitation dipole trend.

How to cite: Du, F., Li, C., He, X., and He, Y.: Moisture source partitioning reveals how human influence shapes the Tibetan Plateau summer precipitation dipole pattern, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4622, https://doi.org/10.5194/egusphere-egu26-4622, 2026.

Roughly half of continental precipitation originates from terrestrial evaporation in upwind regions, yet how these land–atmosphere moisture connections will evolve under climate and land-cover change remains poorly constrained. Earth System Models (ESMs) simulate future precipitation, evaporation, and atmospheric circulation, but they do not explicitly resolve the pathways linking evaporation to downwind precipitation. These pathways can, however, be reconstructed from ESM outputs using moisture tracking.

Here we present different forward- and backward-tracking experiments with the Lagrangian atmospheric moisture tracking model UTrack, forced by multiple CMIP6 ESMs, that quantify future changes in terrestrial moisture recycling across Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) throughout the 21st century. Across models and scenarios, we find an average weakening of terrestrial moisture recycling with warming, with the strongest declines occurring in drying hotspots. In the Amazon rainforest specifically, we find that combined climate change and deforestation may trigger cascading forest transitions mediated by moisture recycling.

We further present results from experiments that investigate whether large-scale ecosystem restoration globally and regionally can counteract specific drying trends through targeted precipitation enhancement.

Our results show that climate change will not only modify precipitation patterns, but will reorganize the continental origins of that precipitation, indicating both future risks for water-stressed ecosystems as well as the potential of ecosystem restoration to mitigate those risks.

How to cite: Staal, A., Lokkart, C., Cai, X., Slagter, M., and Wunderling, N.: Future trajectories of terrestrial moisture recycling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9037, https://doi.org/10.5194/egusphere-egu26-9037, 2026.

Large-scale agricultural activities can intensify atmospheric–terrestrial interactions, of which precipitation recycling plays a critical role. During 1982–2018, irrigated area has dramatically expanded in Northwest China (NWC). In this study, a regional precipitation recycling model—the Brubaker model was used to investigate the precipitation recycling ratio (PRR) and recycled precipitation (RP). Evapotranspiration (ET) estimated by the atmospheric–terrestrial water balance method (A–T) was employed to investigate precipitation recycling. Statistically, there was a turning point in 2002 for the rate in irrigated area increase, from 0.07 × 10⁶ ha/year before 2002 to 0.217 × 10⁶ ha/year after 2002. There were significant shifts in ET, PRR, and RP in NWC, using the turning point of irrigated area expansion as the line of demarcation. The contribution of the change in irrigated area to PRR increased from 18.3% (1982–2002) to 22.9% (2003–2018) in NWC. Prior to 2002, enhanced RP offset the increased ET by 72.9%. After 2002, the positive effect of irrigated area expansion on precipitation recycling disappeared in NWC. Due to the different climate and irrigation practices at the province level, the variations in irrigated area and their contributions to PRR were examined in three provinces, Xinjiang, Gansu, and Shaanxi. Results based on the Brubaker model and Budyko framework indicate that in Xinjiang and Gansu, the contribution of the irrigated area change after the turning point to PRR were 24.5% and -95.6%, respectively, and there is no potential for continued expansion of irrigated area. In Shaanxi, however, there is potential for continued expansion of irrigated area. The methodology for quantifying the impact of irrigated area change on PRR provides reliable references for the sustainable use of cultivated land and the protection of agricultural water resources.

How to cite: Wang, X.: Improved understanding of how irrigated area expansion enhances precipitation recycling by land–atmosphere coupling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2498, https://doi.org/10.5194/egusphere-egu26-2498, 2026.

Agriculture accounts for approximately 70% of global freshwater withdrawals, while around 20% of global cropland is irrigated and supports nearly 40% of total crop production. In an increasingly globalized food system, up to one-third of this production is traded internationally, redistributing the water embedded in crop production, i.e., virtual water, from producing to importing countries. Previous studies have extensively assessed the hydrological and socio-economic impacts of freshwater withdrawals embedded in food trade, focusing on both surface and groundwater resources. However, how irrigation contributes to agricultural production and consequent virtual water exports when returns on land as precipitation through atmospheric transport, is currently unexplored.

This study addresses this gap by quantitatively assessing to what extent irrigation for primary crop production in one country contributes to precipitation in other countries and how this precipitation subsequently supports crop production and trade. The methodology integrates agro-hydrological modelling of the crop evapotranspiration attributable to irrigation with harmonized bilateral datasets on atmospheric moisture transport and virtual water trade.

Specifically, we use the agro-hydrological model waterCROP to estimate the blue water demand associated with 167 primary crops, scaling total virtual water volumes from the CWASI database to blue virtual water flows. These estimates are coupled with atmospheric moisture tracking data from the RECON dataset, a processed version of the Lagrangian output of the UTrack model reconciled with ERA5 reanalysis data for the period 2008–2017. The analysis is conducted at the global scale for the representative year 2013, ensuring consistency between atmospheric moisture flows and virtual water trade datasets.

By coupling these bilateral networks, we construct a new set of water teleconnections that explicitly links agricultural water use to atmospheric moisture transport, precipitation, crop production, and trade. Within this framework, we assess how irrigation in one country contributes to precipitation in other countries, and if this contribution alleviates, compensates, or worsens the need for freshwater withdrawals. This allows us to identify synergies and trade-offs in the geographic redistribution of precipitation originating from irrigation and the associated water use embedded in the international trade of crops.

By revealing how the precipitation originated from the evapotranspiration of irrigated crops contributes to agricultural production beyond national borders, the analysis highlights previously overlooked feedbacks between water use, atmospheric moisture transport, and food trade.

How to cite: De Petrillo, E., Tuninetti, M., Ridolfi, L., and Laio, F.: Irrigation boosts precipitation on cropland for international trade through atmospheric moisture transport, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18978, https://doi.org/10.5194/egusphere-egu26-18978, 2026.

How to cite: Romera-Otero, D. and Míguez-Macho, G.: Deep root vegetation adaptations to drought and their modulation of evapotranspiration (ET) in Africa, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18321, https://doi.org/10.5194/egusphere-egu26-18321, 2026.