Colloquium: Dr. Francina Dominguez | University of Illinois
In-Person PHYS 401
Wednesday, September 11, 2024 · 11 AM - 12 PM
TITLE: "Dry Land Surfaces and Their Effect on Low-Level Moisture Transport in the Americas”
ABSTRACT: In sharp contrast to the sea surface, continental land surfaces experience periods of dryness. During these periods, sensible heat fluxes increase, affecting the lower boundary layer and the atmosphere above. In this presentation I will show how land surface dryness can affect atmospheric circulation and low-level moisture transport over the Americas.
Low-level jets (LLJs) bring moisture for precipitation to many parts of North and South America. These are also some of the most important agricultural regions on Earth. Over North America, we analyze Great Plains Low-Level Jet (GPLLJ) events using ECMWF Reanalysis v5 wind data. Composites of antecedent daily soil moisture anomalies reveal a preference for extreme GPLLJs to occur over anomalously dry soil. The location of the antecedent soil moisture anomalies corresponds with the eventual GPLLJ. Critically, antecedent soil moisture anomalies emerge weeks before the extreme jet occurrence. Similarly, over South America we use remote sensing observations and a global climate model to show that antecedent dry soil moisture anomalies over northwestern Argentina induce a thermal low which affects the winds, moisture fluxes and precipitation over central Argentina. These effects occur a month after the soil moisture anomalies emerge.
The implication of this work is that antecedent (~1 month) soil moisture conditions can provide information about the probability of intense moisture transport and precipitation. The spatiotemporal characteristic of these antecedent anomalies suggests the potential for improved hydroclimate prediction for some of the most important agricultural regions in the world.
ABSTRACT: In sharp contrast to the sea surface, continental land surfaces experience periods of dryness. During these periods, sensible heat fluxes increase, affecting the lower boundary layer and the atmosphere above. In this presentation I will show how land surface dryness can affect atmospheric circulation and low-level moisture transport over the Americas.
Low-level jets (LLJs) bring moisture for precipitation to many parts of North and South America. These are also some of the most important agricultural regions on Earth. Over North America, we analyze Great Plains Low-Level Jet (GPLLJ) events using ECMWF Reanalysis v5 wind data. Composites of antecedent daily soil moisture anomalies reveal a preference for extreme GPLLJs to occur over anomalously dry soil. The location of the antecedent soil moisture anomalies corresponds with the eventual GPLLJ. Critically, antecedent soil moisture anomalies emerge weeks before the extreme jet occurrence. Similarly, over South America we use remote sensing observations and a global climate model to show that antecedent dry soil moisture anomalies over northwestern Argentina induce a thermal low which affects the winds, moisture fluxes and precipitation over central Argentina. These effects occur a month after the soil moisture anomalies emerge.
The implication of this work is that antecedent (~1 month) soil moisture conditions can provide information about the probability of intense moisture transport and precipitation. The spatiotemporal characteristic of these antecedent anomalies suggests the potential for improved hydroclimate prediction for some of the most important agricultural regions in the world.
