Synoptic forcing of precipitation in the Mackenzie and Yukon River basins

Cassano, Elizabeth N.; Cassano, John J.

doi:10.1002/joc.1926

Cited by 33 publications

(32 citation statements)

References 38 publications

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“…Because the Arctic Sea remains frozen for most of the year, Inuvik can be considered to have a continental climate. Generally heat and moisture enter the region by advection over the Cordillera from the Pacific Ocean (Lackmann et al, 1998;Smirnov and Moore, 1999;Szeto, 2008;Cassano and Cassano, 2009). Iqaluit is located in a fjord on Baffin Island in the Labrador Sea.…”

Section: Climatologymentioning

confidence: 99%

Trends in Canadian surface temperature variability in the context of climate change

Turner¹,

Gyakum

2010

Atmosphere-Ocean

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Section: Climatologymentioning

confidence: 99%

Trends in Canadian surface temperature variability in the context of climate change

Turner¹,

Gyakum

2010

Atmosphere-Ocean

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“…rainfall) is determined for the synoptic conditions expressed by each of the SOM nodes (e.g. Cassano and Cassano 2010;Engelbrecht et al 2015;Engelbrecht and Landman 2016;Hewitson and Crane 2002;Schuenemann et al 2008;Verdon-Kidd and Kiem 2009). In an alternative bottom-up approach, synoptic states corresponding to particular weather conditions, e.g.…”

mentioning

confidence: 99%

Interannual rainfall variability and SOM-based circulation classification

et al. 2017

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synoptic variables over a particular location; even though they are used in the development of the SOM their influence, however, diminishes with the size of the SOM spatial domain. The influence of the SOM domain size, the choice of SOM atmospheric variables and grid-point explanatory variables on the levels of explained variance, is consistent with the general understanding of the dominant processes and atmospheric variables that affect rainfall variability at a particular location. Keywords SOM · Synoptic circulation · Rainfall variability · Southern AfricaThe relationship between synoptic circulation and local expressions of climate is the foundation of synoptic climatology and traditionally underpins the process of interpretative weather forecasting. The basic premise of synoptic climatology is that the large-scale atmospheric circulation exerts some control over weather and related environmental phenomena at the Earth's surface, thereby providing a level of deterministic forcing which influences the local weather. This directly leads to the use of atmospheric circulation patterns as a means to express drivers of weather (and climate) variability. Self-Organizing Maps (SOM, Kohonen 2001) is a pattern clustering method that is used as one of the methods to derive synoptic circulation types in this and other contexts, including statistical downscaling (e.g. Hewitson and Crane 2006;Yin et al. 2011;Ohba et al. 2016) and process-based validation of GCMs (e.g. Brown et al. 2010;Finnis et al. 2009;Higgins and Cassano 2010).In the application of SOM to study climate variability, the evolution of synoptic drivers of weather is typically represented by progression through classes of daily synoptic states identified as SOM nodes. That progression Abstract Self-Organizing Maps (SOM) based classifications of synoptic circulation patterns are increasingly being used to interpret large-scale drivers of local climate variability, and as part of statistical downscaling methodologies. These applications rely on a basic premise of synoptic climatology, i.e. that local weather is conditioned by the large-scale circulation. While it is clear that this relationship holds in principle, the implications of its implementation through SOM-based classification, particularly at interannual and longer time scales, are not well recognized. Here we use a SOM to understand the interannual synoptic drivers of climate variability at two locations in the winter and summer rainfall regimes of South Africa. We quantify the portion of variance in seasonal rainfall totals that is explained by year to year differences in the synoptic circulation, as schematized by a SOM. We furthermore test how different spatial domain sizes and synoptic variables affect the ability of the SOM to capture the dominant synoptic drivers of interannual rainfall variability. Additionally, we identify systematic synoptic forcing that is not captured by the SOM classification. The results indicate that the frequency of synoptic states, as schematized by a relatively disa...

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“…Multivariable classifications either classify each variable separately (e.g., Bettolli et al 2010) or use data-reduction techniques (e.g., Stahl et al 2006;Moron et al 2008). Self-organizing maps that are based on MSLP (Cassano and Cassano 2010) or 500-hPa geopotential height (Newton et al 2014a,b) were employed in Canadian studies to assess catchmentscale hydroclimatic variability. These approaches, as noted by Stahl et al (2006), conceal the complex threedimensional nature and internal variability of synoptic types.…”

Section: Introductionmentioning

confidence: 99%

A Synoptic Classification of Inflow-Generating Precipitation in the Snowy Mountains, Australia

Theobald

McGowan

Speirs

et al. 2015

Journal of Applied Meteorology and Climatology

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Precipitation falling in the Snowy Mountains region of southeastern Australia provides fuel for hydroelectric power generation and environmental flows along major river systems, as well as critical water resources for agricultural irrigation. A synoptic climatology of daily precipitation that triggers a quantifiable increase in streamflow in the headwater catchments of the Snowy Mountains region is presented for the period 1958-2012. Here, previous synoptic-meteorological studies of the region are extended by using a longer-term, year-round precipitation and reanalysis dataset combined with a novel, automated synoptic-classification technique. A three-dimensional representation of synoptic circulation is developed by effectively combining meteorological variables through the depth of the troposphere. Eleven distinct synoptic types are identified, describing key circulation features and moisture pathways that deliver precipitation to the Snowy Mountains. Synoptic types with the highest precipitation totals are commonly associated with moisture pathways originating from the northeast and northwest of Australia. These systems generate the greatest precipitation totals across the westerly and high-elevation areas of the Snowy Mountains, but precipitation is reduced in the eastern-elevation areas in the lee of the mountain ranges. In eastern regions, synoptic types with onshore transport of humid air from the Tasman Sea are the major source of precipitation. Strong seasonality in synoptic types is evident, with frontal and cutoff-low types dominating in winter and inland heat troughs prevailing in summer. Interaction between tropical and extratropical systems is evident in all seasons.

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Synoptic forcing of precipitation in the Mackenzie and Yukon River basins

Cited by 33 publications

References 38 publications

Trends in Canadian surface temperature variability in the context of climate change

Trends in Canadian surface temperature variability in the context of climate change

Interannual rainfall variability and SOM-based circulation classification

A Synoptic Classification of Inflow-Generating Precipitation in the Snowy Mountains, Australia

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