The changing nature of ablation-inducing synoptic weather types in the North American Great Lakes basin
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ORIGINAL PAPER
The changing nature of ablation-inducing synoptic weather types in the North American Great Lakes basin Zachary J. Suriano 1
&
Daniel J. Leathers 2
Received: 11 March 2020 / Accepted: 9 November 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The runoff generated by snow cover ablation dominates regional hydrology in the North American Great Lakes basin, while rapid events can represent a physical hazard due to flooding. In determining the likelihood and magnitude of an ablation event, both the presence of snow cover and the synoptic-scale atmospheric environment should be considered, where the atmospheric environment provides the meteorological characteristics and surface energy fluxes necessary for ablation. Pending snowpack availability, variations or changes in the frequency of ablation-inducing synoptic types, and/or varying suitability of meteorological characteristics for snowmelt, can alter the frequency of ablation events. In light of a changing global climate, it is unclear if and how ablation-inducing synoptic types in the Great Lakes basin have transformed in recent decades as from 1960 to 2009, the interannual frequency of snow cover ablation events in the Great Lakes basin has significantly decreased. This study uses synoptic classification as a mechanism for identifying ablation-inducing synoptic weather types and for determining if changes to the frequency and inherent meteorological characteristic of the type are occurring. For a majority of the ten most impactful ablation-inducing synoptic weather types examined, significant trends are noted in their interannual frequencies, which can be partially explained by variations and trends in the phases of common teleconnection indices, such as the North Atlantic and Arctic Oscillations. Collectively, inherent meteorological characteristics of particular weather types in the basin are becoming more suitable for ablation, with increases in surface air temperatures, more southerly wind flow, and less cloud cover, plus increases in liquid precipitation rates during rain-on-snow synoptic types. Independent of snow cover, atmospheric environments suitable for ablation are becoming more frequent and generally more favorable for ablation.
1 Introduction Synoptic classification techniques have become a frequent tool used by climatologists to evaluate the atmosphere’s influence on a surrounding region, where they are utilized to determine the larger-scale atmospheric forcing mechanisms that cause, or create suitable conditions for, smaller-scale atmospheric and surface processes (Yarnal 1993; Lee and Sheridan 2015). The technique often is a means of filtering events by circulation patterns and has been used in recent
* Zachary J. Suriano [email protected] 1
Department of Geography/Geology, University of Nebraska Omaha, 6001 Dodge Street, 267 Durham Science Center, Omaha, NE 68182, USA
2
Department of Geography and Spatial Sciences, University of Delaware, Newark, DE 19716, USA
studies analyzing conditions sui
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