Moisture sources during hydrological extremes in the Midwestern United States

Kim, Seung Uk

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https://hdl.handle.net/2142/115641 Copy

Description

Title

Moisture sources during hydrological extremes in the Midwestern United States

Author(s)

Kim, Seung Uk

Issue Date

2022-04-26

Director of Research (if dissertation) or Advisor (if thesis)

Dominguez, Francina

Committee Member(s)

• Wang, Zhuo
• Proistosescu, Cristian

Department of Study

Atmospheric Sciences

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Hydrological Extremes
• Drought
• Flood
• Land-atmosphere interactions
• Soil moisture

Abstract

Drought and flood are two extreme hydrological events that seriously impact the Central United States, bringing damage of billions of dollars per year. They are especially impactful given the region’s intense agricultural production. Anomalous moisture transport from oceanic and terrestrial sources is known to be a factor in the development of hydrological extreme events. In this study, we use the two-layer dynamic recycling analytical model (2L-DRM) to identify the climatological moisture sources of Midwest precipitation, and then focus on extreme hydrologic events. We find a very different contributions of terrestrial and oceanic sources by season. Terrestrial sources dominate during the warm season (April – September), while oceanic and lake sources during the cold season (October – March). Average daily moisture contribution and its variability increase during the warm season for all regions except the Pacific. We selected extreme hydrological events during the warm season by defining drought as prolonged soil moisture deficit and flood as high precipitation accompanied by excessive soil moisture. An increase in the oceanic sources of moisture due to anomalous flow associated with a strong trough over the continent was observed during two flood cases in 1986 and 1993. Saturated land surface provided additional moisture for floods. On the other hand, two drought cases in 1988 and 2012 showed a large decrease in terrestrial sources due to antecedent dry soil moisture conditions. An intense ridge and associated anomalous northeasterly winds were responsible for reducing moisture import from climatological sources. Interestingly, moisture contribution from lake and forest sources in the western US and Great Lakes increased during drought periods. The Great Lakes sources provided significant moisture to aid in the recovery from severe dryness in 2012.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 SeungUk Kim

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