Extreme landfalling atmospheric river events in Arizona: possible future changes

Singh, Itinderjot

Permalink

https://hdl.handle.net/2142/95512 Copy

Description

Title

Extreme landfalling atmospheric river events in Arizona: possible future changes

Author(s)

Singh, Itinderjot

Issue Date

2016-12-07

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

Dominguez, Francina

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)

• Climate Change
• Atmospheric Rivers
• Pseudo-Global Warming
• Extreme Precipitation

Abstract

The semi-arid Salt and Verde River basins in Arizona depend, in part, on Atmospheric River (AR)-related precipitation for meeting the water demands of the Phoenix metropolitan area. On the other hand, the region is also susceptible to AR-related flooding. In a warming climate, water vapor in the atmosphere increases, thus likely increasing the water vapor transport within ARs. To understand the precipitation-related impacts of climate change on extreme ARs affecting Arizona, a pseudo-global warming (PGW) method was used. High-resolution control and future simulations of five intense historical AR events that affected the Salt and Verde River basin in Central Arizona were carried out. Control simulations realistically captured the magnitude and spatial distribution of precipitation during all five events. The PGW approach for future simulations involved changing the initial and lateral boundary conditions of the input data. The climate change signals of several thermodynamic variables were obtained from an ensemble of 9 General Circulation Models for RCP 8.5 scenario. Two sets of perturbations were applied to the input data. The first set consisted of constant values of temperature change at different vertical levels (PGW1) and the second set consisted of spatially varying temperature values (PGW2). Future simulations showed an overall increase in integrated vertical transport of vapor and upward moisture flux at cloud base over the region for all events. The changes in precipitation at both domain and basin level were highly spatially heterogeneous. Precipitation at the basin level increased in all PGW1 simulations but showed a decrease for some PGW2 simulations. The domain-averaged precipitation increased in all future simulations but the increase remained sub-Clausius-Clapeyron for all but one PGW2 event in which shifting and significant strengthening of the low-level jet was observed. Melting levels rose by more than 600m in all future simulations and this led to a decrease in the fraction of frozen precipitation during the events by more than 80%.

Graduation Semester

2016-12

Type of Resource

text

Permalink

http://hdl.handle.net/2142/95512

Copyright and License Information

Copyright 2016 Itinderjot Singh

Owning Collections