Synoptic Climatology

by

Scott Sheridan, Cameron Lee

• LAST REVIEWED: 20 December 2016
• LAST MODIFIED: 30 January 2014
• DOI: 10.1093/obo/9780199874002-0088

Introduction

Synoptic climatology was born from the desire to better understand synoptic-scale processes of the mid-latitudes: the movement of air masses, pressure centers, weather systems, and fronts across space and in time. Thus, much of the early synoptic climatological literature is based directly or indirectly upon the Bergeron-school theories of the evolution of the mid-latitude cyclone: how and where these cyclones formed, moved, modified, and dissipated, and the surface weather conditions accompanying them and their anticyclonic counterparts. Understanding these systems was achieved through their classification, since comprehending the impacts of a discrete category of typical circulation was much more intuitive than trying to take in all the information available. The satellite and digital eras revolutionized the atmospheric sciences, bringing dynamic climatology into the forefront, since there was a sudden abundance of weather data and the computing power to process it into sophisticated graphic models with predictive capabilities. In the last two decades of the 20th century, synoptic climatology made a resurgence. With dynamic climatology focused on continual improvement of complex climate models, a new appreciation of applied climatological research began to emerge. Holding onto its key defining characteristic—the classification—synoptic climatology added valuable contributions to the knowledge base of how pollution, human health, ecosystems, and a variety of other entities are impacted by weather. The classification of synoptic types provided an indispensable tool by which researchers could analyze these relationships, especially in the context of global climate change. Since the beginning of the 21st century, synoptic climatology has continued to develop as an applied discipline, investigating how discrete categories of weather impact a variety of different outcomes. At the same time, it has also developed as a theoretical discipline, especially in regards to ideal classification techniques. While synoptic climatology got its name from its “synoptic-scale systems” background, and in some ways still aims to analyze these synoptic-scale processes, the discipline has evolved to emphasize the synoptic classification as a key method of approaching an applied climatological research question at any spatiotemporal scale.

Methods

What sets synoptic climatological research apart from other applied climate studies is the process of classification of the atmosphere into discrete types. Thus, a major branch of synoptic-based peer-reviewed literature focuses on the differing approaches and methodologies of classification. Like any subfield, synoptic climatology has its own jargon, which can be confusing to the uninitiated, with some terms being used haphazardly even among those well versed in the field. The confusing jargon manifests most often in describing the lineage of a particular classification, as there are a number of different levels of categories of classifications, with each individual classification being defined at each of these many levels. According to Yarnal 1993, a classification takes either a circulation-to-environment approach (in which atmospheric conditions are first classified and then applied to an outcome) or an environment-to-circulation approach (in which a particular outcome determines which days are classified). A classification can also be undertaken using either a manual, automated, or hybrid methodology. Further, the classification can be approached from one of many different modi operandi, such as a map/circulation pattern classification, a weather type/air mass classification, a regionalization, a combination of these, or others. Finally, each classification also has its own specific methodology, and it is these specific methodologies that will be outlined in the subsections below. However, for a detailed guide to help navigate one through this complex terminology, a thorough reading of Yarnal 1993 is highly recommended. The book chapter Barry and Perry 2001 provides an extensive bibliography of synoptic research that encompasses the breadth of the discipline. Huth, et al. 2008 presents a more updated overview of some of these key methodologies, with a greater focus on European contributions to the field, and Philipp, et al. 2010 is a key starting point for a critical undertaking in recent years to evaluate major European-oriented classification techniques. While a thorough understanding of concepts, processes, and ranges of use of synoptic climatology will only be achieved by immersing oneself into the field, the following four references provide a solid foundation for the novice, and a refresher on the fundamentals for the expert.

• Barry, R. G., and A. H. Perry. “Synoptic Climatology and Its Applications.” In Synoptic and Dynamic Climatology. By R. G. Barry and A. H. Perry, 547–603. New York: Routledge, 2001.

  Book chapter devoted to a detailed description of classification strategies along with overviews of methods and important synoptic catalogs. Includes a lengthy discussion on applications of methods. Lengthy, comprehensive bibliography.

• Huth, R., C. Beck, A. Philipp, et al. “Classifications of Atmospheric Circulation Patterns.” Annals of the New York Academy of Sciences 1146.1 (2008): 105–152.

  DOI: 10.1196/annals.1446.019

  Review manuscript focusing on circulation pattern classifications. Discusses general concepts and categories of classifications and overviews more recent advances in the discipline. Focus is on European classifications, including efforts to find an optimal method. Quantitative evaluation of different methodologies, and examples of applications are also given.

• Philipp, A., J. Bartholy, C. Beck, et al. “Cost733cat—A Database of Weather and Circulation Type Classifications.” Physics and Chemistry of the Earth, Parts A/B/C 35.9 (2010): 360–373.

  DOI: 10.1016/j.pce.2009.12.010

  One of twenty-nine articles in a special issue of the journal devoted to the COST733 action—a major effort to evaluate and optimize European synoptic pattern classifications. Provides a database with dozens of classifications, along with brief technical descriptions and comparisons of the methods with a variety of different metrics.

• Yarnal, B. Synoptic Climatology in Environmental Analysis: A Primer. London: Belhaven, 1993.

  Provides the most recent extensive overview of synoptic climatology, with definitions and limitations of the discipline and relevant literature. Includes detailed descriptions of methods, caveats and benefits of each, and worked examples. One of the first examples of principal component analysis (PCA)-based methodologies for circulation (map) pattern classifications. Very widely cited book.