Ms. Isioma Jessica Nwayor was awarded first place in the 2023 AAG Climate Student Group Competition for her paper titled “Exploring the Use of the Standardized Vapor Pressure Deficit Index (SVPDI) in Analyzing Drought Changes.” The work has since been published under the title “A Multiscalar Standardized Vapor Pressure Deficit Index for Drought Monitoring and Impacts.”

This study introduces the Standardized Vapor Pressure Deficit Index (SVPDI)—a novel tool that enables researchers to track atmospheric water demand and monitor drought conditions across diverse ecosystems and climates. Building on the well-established role of vapor pressure deficit (VPD) as a key indicator of atmospheric dryness, the SVPDI provides a standardized, probabilistic framework for comparing VPD trends across different timescales and climate types.

Unlike existing drought indices, the SVPDI isolates the atmospheric component of drought and can capture stress in vegetation not fully explained by other indices. Developed using the gamma distributions across multiple timescales (1-, 3-, 6-, and 12-month), the SVPDI trend shows more widespread signals of drying globally between 1958 and 2023 compared to the Standardized Precipitation Evapotranspiration Index (SPEI).

The study finds that SVPDI and SPEI are the most different in the humid and arid regions. In addition, case studies of recent severe droughts across four global hotspots show that SVPDI has consistently detected longer and more intense drought events than SPEI in the past decade.

With climate change driving increased VPD, this new index offers a critical advancement for ecosystem monitoring, agricultural planning, and climate adaptation strategies.

Ms. Nwayor is a fifth-year PhD student in the Department of Geography at Indiana University Bloomington.

For more information, see Ms. Nwayor's article in the International Journal of Climatology: Nwayor, I.J., Robeson, S.M., Ficklin, D.L. and Maxwell, J.T., 2024. A Multiscalar Standardized Vapor Pressure Deficit Index for Drought Monitoring and Impacts. International Journal of Climatology, 44(16), pp.5825-5838.