Daily weather conditions for an entire city are usually represented by a single weather station, often located at a nearby airport. This resolution of atmospheric data fails to recognize the microscale climatic variability associated with land use decisions across and within urban neighborhoods. This study uses heat index, a measure of the combined effects of temperature and humidity, to assess the variability of heat exposure from ten weather stations across four urban neighborhoods and two control locations (downtown and in a nearby nature center) in Knoxville, Tennessee, USA. Results suggest that trees may negate a portion of excess urban heat, but are also associated with greater humidity. As a result, the heat index of locations with more trees is significantly higher than downtown and areas with fewer trees. Trees may also reduce heat stress by shading individuals from incoming radiation, though this is not considered in this study. Greater amounts of impervious surfaces correspond with reduced evapotranspiration and greater runoff, in terms of overall mass balance, leading to a higher temperature, but lower relative humidity. Heat index and relative humidity were found to significantly vary between locations with different tree cover and neighborhood characteristics for the full study time period as well as for the top 10% of heat index days. This work demonstrates the need for high-resolution climate data and the use of additional measures beyond temperature to understand urban neighborhood exposure to extreme heat, and expresses the importance of considering vulnerability differences among residents when analyzing neighborhood-scale impacts.

Annual suicide deaths outnumber the total deaths from homicide and war combined. Suicide is a complex behavioral endpoint, and a simple cause-and-effect model seems highly unlikely, but relationships with weather could yield important insight into the biopsychosocial mechanisms involved in suicide deaths. This study has been designed to test for a relationship between air temperature and suicide frequency that is consistent enough to offer some predictive abilities. Weekly suicide death totals and anomalies from Toronto, Ontario, Canada (1986–2009) and Jackson, Mississippi, USA (1980–2006) are analyzed for relationships by using temperature anomaly data and a distributed lag nonlinear model. For both analysis methods, anomalously cool weeks show low probabilities of experiencing high-end suicide totals while warmer weeks are more likely to experience high-end suicide totals. This result is consistent for Toronto and Jackson. Weekly suicide totals demonstrate a sufficient association with temperature anomalies to allow some prediction of weeks with or without increased suicide frequency. While this finding alone is unlikely to have immediate clinical implications, these results are an important step toward clarifying the biopsychosocial mechanisms of suicidal behavior through a more nuanced understanding of the relationship between temperature and suicide.

a b s t r a c t Study region: Upper Tennessee River Basin, United States. Study focus: The temporal variation of precipitation in the Upper Tennessee River Basin was investigated by utilizing datasets from the Tennessee Valley Authority (TVA) rain gauge network consisting of 56 rain gauges , and the National Weather Service (NWS) analyzing mean areal precipitation values for 78 subbasins . The Mann-Kendall trend test, Mann-Kendall-Sneyers test, Yamamoto Method, and Morlet's wavelet were applied to reveal precipitation trends and abrupt changes in annual precipitation volumes. New hydrological insights for the region: Analyses indicated that: (a) 11% of the 78 subbasins experienced statistically significant increasing or decreasing precipitation over a 50-year period; (b) seasonal precipitation trends based on monthly volumes varied, with the summer and autumn series showing the largest significant increases; (c) abrupt changes in annual precipitation volumes were detected among subbasins corresponding to strong El Niño events; and (d) several subbasins displayed significant periodicities of 1, 6, 18, and 22 years in monthly volumes. These findings provide key information for regional precipitation down-scaling from global climate change models where the Appalachian mountainous terrain greatly impacts down-scaling results.

Nocturnal tornadoes are a public health threat, over twice as likely to have fatalities as tornadoes during the day. While tornado warning receipt is an important factor in models of individual behavioral response, receipt of warnings at night has not been studied in the literature to date. This study uses survey data from a random sample of Tennessee residents (N = 1804) who were randomly assigned to day or night versions of a near-identical survey instrument. Bivariate and logistic regression analyses compare chance of warning receipt, warning sources, and predictors of warning receipt for day versus night scenarios of a tornadic event. Over 80% of participants asked about a daytime tornado said there was a high/very high chance of receiving the warning, compared to fewer than 50% of participants asked about a nighttime event. Whereas demographic and cognitive factors helped predict tornado warning receipt during the day, cognitive and geographic factors were salient for the night. Perceived county risk and prior experience with a tornado were positively associated with chance of nighttime receipt, while belief that luck is an important factor in surviving a tornado and living in east (compared to west) Tennessee were negatively associated. Future research should consider partnering with the National Weather Service, emergency managers, and local media to increase the likelihood that people will receive tornado warnings at night and to better understand the role that cognitive factors and particular beliefs play in individual efforts to ensure that warnings are received.

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