Moisture sources during hydrological extremes in the Midwestern United States

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.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Atmospheric Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Kim, Seung Uk

Contributors dc:contributor

• Dominguez, Francina
• Wang, Zhuo
• Proistosescu, Cristian

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

Statement dc:rights

• Copyright 2022 SeungUk Kim

Language dc:language

en, eng

Handle dc:identifier

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

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115641