The Mashash Desert Climate Observatory: A New Megasite for Air–Land Exchange Processes in Subtropical Deserts

Arid and hyper-arid regions (deserts) are dynamic ecosystems that respond sensitively to changes in water availability, temperature, and atmospheric CO₂, and can both indicate and influence climate change. Although approximately 27% of the world’s land surface is classified as deserts, these regions are second only to oceans in the scarcity of long-term measurement sites. This results in an inadequate representation of the complex interactions among the pedosphere, hydrosphere, and atmosphere in these regions. This knowledge gap limits understanding of desert-specific air–land processes and, given the close coupling between desert climates and the global system, contributes to uncertainty in climate projections.To address this gap, we are establishing a first-of-its-kind megasite in the Negev Desert representing the subtropical desert belt. Israel’s relatively small size, with ~60% of its territory classified as arid or hyper-arid, makes the Negev uniquely accessible for long-term observations. The Mashash Desert Climate Observatory is built on a record of meteorological data collected at the site since 1973 and extensive micrometeorological measurements conducted in recent years.The new megasite will generate vertically resolved surface-to-atmosphere profiles of wind, temperature, and moisture, along with detailed radiation, heat, CO2, and dust fluxes, enabling direct analysis of air–land coupling from the soil to the top of the troposphere. Co-located measurements of soil moisture, soil heat flux, and soil CO₂ efflux will allow characterization of subsurface controls on surface energy partitioning and carbon exchange. These continuous estimates will highlight the evolution of dynamics at diurnal, seasonal, and annual scales, linking surface radiative forcing to turbulent transport and boundary-layer development. Combined radiative and thermodynamic profiles will further resolve the vertical structure of moisture transport and non-precipitating systems, clarifying how episodic hydrological inputs propagate through the soil–vegetation–atmosphere continuum in desert environments. The observatory will be open to the international research community, and its data architecture is designed to be compatible with global networks (e.g., FLUXNET and NASA archiving standards), while maintaining access to raw data to ensure transparency and scientific integrity.By providing sustained observations of air–land interactions in an understudied environment, the Mashash Desert Climate Observatory will deliver essential data for improving land-surface and boundary-layer models, support model–observation intercomparisons and remote-sensing validation, and advance understanding of multi-scale desert processes toward initial upscaling to global climate models.