The climatology of synoptic-scale ascent over Western North America: a perspective on storm tracks

pre-printThe position and variability of storm tracks across western North America are examined during the October-April cool seasons spanning 1989-2010. The location and intensity of storms are represented by strong synoptic-scale ascent, which is diagnosed by the alternative balance omega equation applied to ECMWF Re-Analysis Interim data. This dynamically filtered method removes poorly resolved updrafts arising from subsynoptic-scale phenomena such as convection and mountain waves. The resulting vertical motions are illustrated for the case of a strong storm traversing the western United States. Summary statistics of synoptic-scale ascent are compiled over months, seasons, and the entire 21-yr period. Locations exhibiting high mean values of ascent are deemed to represent storm tracks. The climatological-mean storm track exhibits a sinusoidal shape across the eastern Pacific and western North America. The composite evolution of strong storms moving along specific segments of the storm track show regional differences (e.g., storms poleward of 508N tend to result from progressive low-amplitude troughs progressing through the mean planetary ridge, while storms over the western United States are initiated by digging troughs that temporarily suppress the mean ridge). Seasonal shifts in the storm track are pronounced and exhibit coherent regional patterns. Interannual variations in synoptic-scale ascent indicate meridional shifts in position as well as changes in the degree of amplification within the dominant sinusoidal storm track. These changes in structure are related to the phase of ENSO: El Nin˜ o (La Nin˜ a) winters favor zonal (amplified) and southern (northern) storm tracks

Observing snow and wind: using the environment to engage students in science and engineering

posterThis study focused on the effectiveness of new curriculum that was integrated with hands on environmental instrumentation and student learning. The goals of this study were to increase student proficiency with environmental instrumentation, as well as enhance student confidence to use technologies to observe the environment and solve real-world problems. A description of activities used and feedback received are included

Idealized large-eddy simulations of sea and lake breezes: sensitivity to lake diameter, heat flux and stability

ManuscriptIdealized large-eddy simulations of lake and sea breezes are conducted to deter mine the sensitivity of these thermally-driven circulations to variations in the land-surface sensible heat flux and initial atmospheric stability. The lake-breeze and sea-breeze metrics of horizontal wind speed, horizontal extent, and depth are assessed. Modelled asymmetries about the coastline in the horizontal extent of the low-level onshore flow are found to vary as a function of the heat flux and stability. Small lake breezes develop similarly to sea breezes in the morning, but have a significantly weaker horizontal wind speed component and a smaller horizontal extent than sea breezes in the afternoon

Association between neighborhood need and spatial access to food stores and fast food restaurants in neighborhoods of Colonias

Objective To determine the extent to which neighborhood needs (socioeconomic deprivation and vehicle availability) are associated with two criteria of food environment access: 1) distance to the nearest food store and fast food restaurant and 2) coverage (number) of food stores and fast food restaurants within a specified network distance of neighborhood areas of colonias, using ground-truthed methods. Methods Data included locational points for 315 food stores and 204 fast food restaurants, and neighborhood characteristics from the 2000 U.S. Census for the 197 census block group (CBG) study area. Neighborhood deprivation and vehicle availability were calculated for each CBG. Minimum distance was determined by calculating network distance from the population-weighted center of each CBG to the nearest supercenter, supermarket, grocery, convenience store, dollar store, mass merchandiser, and fast food restaurant. Coverage was determined by calculating the number of each type of food store and fast food restaurant within a network distance of 1, 3, and 5 miles of each population-weighted CBG center. Neighborhood need and access were examined using Spearman ranked correlations, spatial autocorrelation, and multivariate regression models that adjusted for population density. Results Overall, neighborhoods had best access to convenience stores, fast food restaurants, and dollar stores. After adjusting for population density, residents in neighborhoods with increased deprivation had to travel a significantly greater distance to the nearest supercenter or supermarket, grocery store, mass merchandiser, dollar store, and pharmacy for food items. The results were quite different for association of need with the number of stores within 1 mile. Deprivation was only associated with fast food restaurants; greater deprivation was associated with fewer fast food restaurants within 1 mile. CBG with greater lack of vehicle availability had slightly better access to more supercenters or supermarkets, grocery stores, or fast food restaurants. Increasing deprivation was associated with decreasing numbers of grocery stores, mass merchandisers, dollar stores, and fast food restaurants within 3 miles. Conclusion It is important to understand not only the distance that people must travel to the nearest store to make a purchase, but also how many shopping opportunities they have in order to compare price, quality, and selection. Future research should examine how spatial access to the food environment influences the utilization of food stores and fast food restaurants, and the strategies used by low-income families to obtain food for the household

Atmospheric conditions in the Atlantic sector during 1983 and 1984

The dramatic global climate variability during the period from 1982 to 1984 has presented a unique opportunity to diagnose and interpret the role of air/sea interactions over the tropical oceans. Recent reviews have summarized the observational and numerical evidence for air/sea interactions over the equatorial Pacific Ocean associated with the El Nino/Southern Oscillation (ENSO) phenomenon l-3. Here we present details of the atmospheric condi- tions in the Atlantic sector between 1983 and 1984. During the latter half of 1983, the atmospheric circulation over the equatorial Atlantic underwent a dramatic reversal: surface trade winds were substantially reduced; surface pressures decreased; and cloudiness and rainfall increased over the ocean and adjacent regions of north-east Brazil. These regional changes over the equatorial Atlantic coincided with planetary-scale adjustments in the tropical atmosphere. While the atmospheric circulation over the tropical Pacific was experiencing an extraordinary departure from normal during 1983, as evidenced by a reversal in direction of the surface winds, the circulation over the Atlantic was in a building-up phase with stronger than usual surface winds. As the atmospheric circulation over the Pacific returned to normal during the latter half of 1983, the frade winds over the Atlantic relaxed.Pages: 248-25