Date of Award

Spring 2023

Project Type

Thesis

Program or Major

Earth Sciences

Degree Name

Master of Science

First Advisor

Elizabeth A Burakowski

Second Advisor

Adam R Herrington

Third Advisor

Katharine A Duderstadt

Abstract

Atmospheric rivers (ARs) are synoptic-scale features that transport moisture poleward and have been shown to cause short duration, high-volume melt events in the Greenland ice sheet (GrIS). This project supports the effectiveness of variable-resolution (VR) grids in modeling ARs and their subsequent precipitation around the GrIS using a study period of 1 January 1979 to 31 December 1998. VR simulations from the Community Earth System Model (CESM2) bridge the gap between limitations of global climate models and regional climate models while maximizing computational efficiency. VR grids improve the representation of ARs, in part by resolving small-scale processes. ARs are identified in the CESM2 using three grid types (VR, latitude-longitude, and quasi-uniform) of varying resolutions and comparison to output of the observation-based reanalysis product, ERA5. The VR grids produce a smaller areal extent than latitude-longitude and quasi-uniform grids, as well as lower integrated precipitation. We hypothesize that the smaller areal extents in VR grids are produced by the refined topography resolved in these grids. Due to the coarser resolution in latitude-longitude and quasi-uniform grids, smoothing occurs therefore allowing ARs to penetrate further inland into the GrIS. This areal extent also likely causes the lower area-integrated cumulative precipitation occurring in the VR grids, as the area-average cumulative precipitation is similar for VR, latitude-longitude, and quasi-uniform grids. The VR grids behave the most similarly to ERA5 in these two metrics, therefore suggesting that they describe AR behavior and subsequent precipitation the most accurately among the three grid configurations included in this study.

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