Investigating surface water loss in southern Italian Apennines: validation of the IASI-based Water Deficit Index with ground-stations measurements
Assigned Session: FS 3.115: Drought in mountain regions
Abstract ID: 3.10897 | Accepted as Talk | Requested as: Talk | TBA | TBA
Pamela Pasquariello (1)
Guido, Masiello (1); Carmine, Serio (1); Vito, Telesca (1); Marco, D'Emilio (1); Giuliano, Liuzzi (1); Fabio, Della Rocca (3, 4); Rocco, Giosa (1); Lorenzo, Cassini (1, 2); Italia, De Feis (4); Sara, Venafra (5)
(1) University of Basilicata, Via dell'Ateneo Lucano, 10, 85100 Potenza, IT
(2) University of Rome "La Sapienza", Piazzale Aldo Moro 5, 00185 Rome, Italy
(3) University of Naples "Federico II", Corso Umberto I 40, 80138 Naples, Italy
(4) IAC-CNR, Via Pietro Castellino 111, 80131 Naples, Italy
(5) Italian Space Agency, Via del Politecnico snc, 00133 Rome, Italy
Abstract
Surface dryness poses a significant threat to ecological landscapes, especially mountainous areas. Its impact on woodlands is particularly pronounced in Mediterranean Europe, with southern Italy being one of the most affected areas due to extreme summer heatwaves and scarce rainfall. In this context, identifying the occurrence of surface water loss can enhance our understanding of its dynamics and support stakeholders and policymakers in taking timely and appropriate actions. Since air water content depends on both surface and dew point temperatures, we selected the Water Deficit Index (WDI) to investigate its effectiveness in identifying water loss from the surface to the atmosphere in part of southern Italy, focusing on the period 2015–2023. WDI is defined as the difference between surface and dew point temperatures, directly reflecting variations in water content between the surface and the lower atmosphere: the higher its value, the faster the water loss. This index was estimated from hyperspectral satellite data acquired by the Infrared Atmospheric Sounding Interferometer (IASI) onboard EUMETSAT’s MetOp polar satellites. IASI’s spectral range spans from 645 to 2760 cm⁻¹, with a sampling interval of 0.25 cm⁻¹, resulting in 8461 spectral channels. IASI radiances were processed using phi-IASI, a physical inversion scheme that simultaneously retrieves a comprehensive state vector of atmospheric and surface quantities, including temperature and water vapor profiles, as well as surface temperature and the emissivity spectrum. Ground station measurements of air temperature, relative humidity, and precipitation provided by local environmental agencies were also used for comparison with IASI retrievals, alongside surface soil moisture derived from Copernicus’ Sentinel-1 acquisitions. The selected datasets were co-located and compared over the period of interest, highlighting a clear relationship between emissivity, temperature, and water loss from the surface to the atmosphere. The primary limitation of this methodology is the spatial resolution of the TIR data. However, this index could prove even more effective if estimated using higher-resolution instruments, such as NASA-ASI’s Surface Biology and Geology Observing Terrestrial Thermal Emission Radiometer (SBG-OTTER), enabling more precise monitoring of small, heterogeneous areas where multiple land covers coexist, exhibiting different responses to water stress.
N/A | ||||||||
|