Synoptic climatology of the long-distance dispersal of white pine blister rust. I. Development of an upper level synoptic classification

Abstract

This study developed a methodology to temporally classify large scale, upper level atmospheric conditions over North America, utilizing a newly-developed upper level synoptic classification (ULSC). Four meteorological variables: geopotential height, specific humidity, and u- and v-wind components, at the 500 hPa level over North America were obtained from the NCEP/NCAR Reanalysis Project dataset for the period 1965-1974. These data were subjected to principal components analysis to standardize and reduce the dataset, and then an average linkage clustering algorithm identified groups of observations with similar flow patterns. The procedure yielded 16 clusters. These flow patterns identified by the ULSC typify all patterns expected to be observed over the study area. Additionally, the resulting cluster calendar for the period 1965-1974 showed that the clusters are generally temporally continuous. Subsequent classification of additional observations through a z-score method produced acceptable results, indicating that additional observations may easily be incorporated into the ULSC calendar. The ULSC calendar of synoptic conditions can be used to identify situations that lead to periods of extreme weather, i.e., heat waves, flooding and droughts, and to explore long-distance dispersal of airborne particles and biota across North America.

Synoptic climatology of the long-distance dispersal of white pine blister rust II. Combination of surface and upper-level conditions

“…Although a flight from California is more than 1,200 km, the rust also appears to have completed other, somewhat shorter dispersals (Geils et al 2003), and longer distances for other rusts are reported (Nagarajan and Singh 1990). Source regions such as Oregon, Idaho and Wyoming cannot be ruled out; few, infrequent synoptic patterns (Frank et al 2008, this issue) would transport rusts from these locations to south-central New Mexico.…”

“…The patterns of upper level flow identified by the ULSC (Frank et al 2008, this issue) describe the potential connections between source and target locations. Although host and rust populations have patchy distributions at various landscape scales, they can be mapped at a county level using data from published literature, herbarium records, and field reports (Fig.…”

Epidemiology of white pine blister rust on limber pine in Colorado and Wyoming

“…Most long‐distance spread of WPBR likely occurs through movement of thick‐walled aeciospores, which are produced on pines and fairly resistant to desiccation and UV radiation (Frank, Geils et al., ; Kasanen, ; Zambino, ). Wind speed, wind direction, and local and regional climate and weather systems are integral forces that impact plant disease epidemics through their relationship with spore dispersal, but studies in complex mountain meteorology are difficult (Aylor, ; Frank, Kalkstein, Geils, & Thistle, ; Holdenrieder et al., ; Jacobi, Geils, & Taylor, ; Jacobi, Geils, Taylor, & Zentz, ; Mielke, ). Winds must move in the appropriate direction from the spore source to the host location, which can be challenging to model in the complex topography of the Rocky Mountains as observed in tree line communities of whitebark pine and with comandra blister rust ( Cronartium comandrae Pk.)…”

Perspectives on the Synoptic Climate Classification and its Role in Interdisciplinary Research

“…The current SSC was developed by Sheridan () and was referred to as “SSC2” because it stemmed from an extensive line of research initiated by Muller, Kalkstein, and others in the late 1970s (Kalkstein et al ; Lamb ; Muller ) that eventually led to an initial version that is sometimes referred to as “SSC1” (see Hondula et al for an in‐depth history). A combination of weather variables (air temperature, dew‐point depression, wind speed, mean cloud cover, mean sea‐level pressure, diurnal temperature range, and diurnal dew‐point range) 6is used to numerically characterize the state of the atmosphere; these quantities are subsequently differentiated into weather‐type categories, encompassing variables that synergistically affect human health (Davis et al ; Greene et al ) and various ecological systems (e.g., Frank et al ,).…”