A procedure for blending manual and correlation‐based synoptic classifications

Frakes, Brent; Yarnal, Brent

doi:10.1002/(sici)1097-0088(19971115)17:13<1381::aid-joc204>3.3.co;2-h

Cited by 12 publications

(17 citation statements)

References 9 publications

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“…If not, it was given an unclassified designation. This hybrid approach differs markedly from that used by and Frakes and Yarnal (1997), but provides an objective selection of the predominant synoptic types. The manual classification of individual synoptic maps to predefined map patterns is among the most subjective exercises in manual classification exercises (Yarnal, 1993).…”

Section: Methodsmentioning

confidence: 99%

Autumn synoptic conditions and rainfall in the subarctic Canadian Shield of the Northwest Territories, Canada

Spence

Rausch

2005

Int. J. Climatol.

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Autumn precipitation is important to the annual water budget and spring streamflow magnitude in the subarctic Canadian Shield portion of the Mackenzie Basin in northwestern Canada. The objective of this study is to improve understanding of the synoptic mechanisms generating this autumn precipitation by investigating a wet (1998) and a dry (1999) autumn over a portion of this region north of Great Slave Lake. Seven synoptic map patterns were identified using a hybrid manual-revised Kirchhofer correlation methodology. Cyclones were found to be the most important map pattern providing autumn rainfall. These cyclones tend to occur 2 to 3 days following the presence of a low in the Gulf of Alaska near the Aleutian Islands. The results of this study corroborate past research that shows Pacific atmospheric moisture transported inland provides the source for much of the cyclonic rainfall in the Mackenzie Basin. Aleutian lows, which encourage this transportation, were as common in 1998 as in 1999, but the mechanisms necessary to transfer moisture to the North Great Slave region were more entrenched in 1998 than in 1999. Winds along storm tracks through the region were weaker and more dispersed in 1999. In addition, conditions for cyclogenesis in the region were less favourable in 1999.

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Section: Methodsmentioning

confidence: 99%

Autumn synoptic conditions and rainfall in the subarctic Canadian Shield of the Northwest Territories, Canada

Spence

Rausch

2005

Int. J. Climatol.

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“…At this stage, the decision on the correlation coefficient used was crucial. In climatological classification studies, values within the range 0.5-0.7 are typically satisfactory (Yarnal, 1993), while pitfalls have been detected related to stricter thresholds (Frakes and Yarnal, 1997). Several correlation coefficients were tested, since high coefficients classified a small number of additional days, while lower coefficients classified one day in more than one pattern, as some daily patterns constitute transitional modes between two of the defined patterns.…”

Section: Evaluation Analysis Of Circulation Typesmentioning

confidence: 99%

Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: map‐pattern classification

Κωστοπούλου

Jones

2007

Intl Journal of Climatology

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Abstract:This paper provides an extended study of the dominant daily circulation patterns governing the climate variability in the eastern Mediterranean. The methodology adopted to determine the circulation patterns is based on combined analysis of the spatial and temporal variation of rotated principal components of sea-level pressure. A catalogue of characteristic seasonal composites is presented and discussed. It is found that, during winter and spring, large scale features situated in northern Europe affect the atmospheric circulation over the domain of study, whereas the Atlantic (Azores) anticyclone and the Asian Thermal Low define most of the observed circulation types in summer. In autumn, the area exhibits a rapid transition from the warm to cold season showing climatic features from both extreme seasons. Similarities between winter and spring/autumn patterns are detected and correlation analyses are employed between their spatial patterns to reveal that similar circulation patterns occur amongst the three seasons, which usually appear more pronounced during winter. Frequencies and trends of the proposed circulation types are examined for each season. A linear trend analysis for the overall period exhibits a significant increase in the anticyclonic types particularly in winter. With respect to the cyclonic types, statistically significant negative trends have been found in all seasons especially for types associated with depressional activity in central the Mediterranean.

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“…A detailed discussion of the advantages and disadvantages of both methods can be found in Frakes and Yarnal (1997). Overall, the first group relies on statistical techniques for classification, including among others, principal components analysis (Esteban et al, 2005), canonical correlation analysis (Xoplaki et al, 2003), and cluster analysis (Littmann, 2000).…”

Section: Introductionmentioning

confidence: 99%

Multi-decadal classification of synoptic weather types, observed trends and links to rainfall characteristics over Saudi Arabia

Kenawy

McCabe

Stenchikov

et al. 2014

Front. Environ. Sci.

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An automated version of the Lamb weather type classification scheme was employed to characterize daily circulation conditions in Saudi Arabia from 1960 to 2005. Daily gridded fields of sea level pressure (SLP) from both the NCEP/NCAR and the European Center for Medium-Range Weather Forecast (ECMWF) reanalysis data (ERA40) were used as input data for this classification. The output catalog included 10 basic types, which describe the direction and vorticity of airflow in the region (i.e., cyclonic, anti-cyclonic, and directional). In general, our findings indicate that cyclonic (C) days represent the most frequent type among all days, with 69.2% of the annual count of days from 1960 to 2005, followed by SE directional flows (21%). It was also determined that airflows originating from the Indian Ocean (i.e., S, SE, and E) are more frequent than those from the Mediterranean and Red Seas (i.e., W, NW, and SW). The defined weather types were assessed for the presence of inter-annual and intra-annual trends using the Mann-Kendall tau statistic. The trend analysis suggests statistically significant changes in the frequencies of a majority of the weather types from 1960 to 2005. The relationship between the daily occurrence of rainfall and the frequency of individual weather types was also described using daily rainfall data from a network of 87 weather observatories. Results demonstrate that increasing frequencies of weather types connected to easterly inflows support higher precipitation amounts over the study domain. Characterizing the association between atmospheric circulation patterns and rainfall in Saudi Arabia is important for understanding potential impacts related to climate variability and also for developing circulation-based downscaling methods.

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A procedure for blending manual and correlation‐based synoptic classifications

Cited by 12 publications

References 9 publications

Autumn synoptic conditions and rainfall in the subarctic Canadian Shield of the Northwest Territories, Canada

Autumn synoptic conditions and rainfall in the subarctic Canadian Shield of the Northwest Territories, Canada

Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: map‐pattern classification

Multi-decadal classification of synoptic weather types, observed trends and links to rainfall characteristics over Saudi Arabia

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