Brent C. Hedquist

Evening Transition Observations in Phoenix, Arizona

Abstract Past research has suggested that the evening transition in complex topography typically has several main features, such as (a) continued weak upslope flows persisting 3–5 h after sunset (if the sidewalls of the valley prevent Coriolis-induced turning of winds), thus signifying delayed transition; (b) unsteady local stagnation and vertical mixing within tens of meters above the surface; and (c) transition of stagnation fronts to downslope/downvalley gravity currents during the evening hours, especially at higher-elevation (steeper) slopes, and their arrival at adjoining low-elevation gentle slopes as “slope breezes.” This transition process typically occurs in locales such as Phoenix, Arizona, which has expansive exposure to plains in one direction (to the west and south) and is adjacent to abrupt change in the terrain in other directions (primarily to the north and east). An analysis of wind records from several automated weather stations and a radar wind profiler for selected characteristic peri...

Urban, Residential, and Rural Climate Comparisons from Mobile Transects and Fixed Stations: Phoenix, Arizona

Abstract Fixed stations versus automobile transects were compared for a 27-day period between July and November 2001 to investigate urban, residential, and rural temperatures and dew points post-sundown for a sub-region in the metropolitan area of Phoenix, Arizona. Temperature and dew point differences were determined among urban (urb), residential (res), and rural (rur) from the fixed sites (fix) and the mobile transect route (tran). On average, transects revealed a mean ΔT(urb-rur)tran of 7.3°C (standard deviation, σ, of 2.02°C) and ΔT(res-rur)tran of 3°C (σ = 1.09°C); whereas the fixed site results were ΔT(urb-rur)fix of 4.8°C (σ = 2.78°C) and ΔT(res-rur)fix of 2.3°C (σ = 1.81°C). Comparisons of dew points for ΔTd(urb-rur)tran and ΔTd(res-rur)tran were −3.21°C (σ = 4.56°C) and −1.0°C (σ = 1.44°C), respectively; whereas the ΔTd(urb-rur)fix and ΔTd(res-rur)fix values averaged +1.27°C (σ = 2.85°C) and −0.10°C (σ = 2.75°C), respectively. The use of a Soil-Adjusted Vegetation Index (SAVI) assists in interpreting the overall results of the differences among sites and highlights the important role of surface vegetation and moisture in reducing temperatures in this desert urban setting. An ongoing mobile climate sampling system is planned within the Central Arizona-Phoenix Long-Term Ecological Research program (CAP LTER) to maintain seasonal and long-term climate sampling in order to determine local details linking urban ecology and land cover change to climate change in this metropolitan region.

HEAT MORTALITY VERSUS COLD MORTALITY A Study of Conflicting Databases in the United States

Abstract Studies, public reports, news reports, and Web sites cite a wide range of values associated with deaths resulting from excessive heat and excessive cold. For example, in the United States, the National Climatic Data Centers Storm Data statistics of temperature- related deaths are skewed heavily toward heat-related deaths, while the National Center for Health Statistics Compressed Mortality Database indicates the reverse—4 times more people die of “excessive cold” conditions in a given year than of “excessive heat.” In this study, we address the fundamental differences in the various temperature-related mortality databases, assess their benefits and limitations, and offer suggestions as to their use. These datasets suffer from potential incompleteness of source information, long compilation times, limited quality control, and the subjective determination of a direct versus indirect cause of death. In general, these separate mortality datasets should not be combined or compared, particularly with ...

Climate Modeling for Renewable Energy Applications

CorrespondenceshouldbeaddressedtoHuei-PingHuang;hp.huang@asu.eduReceived27November2014;Accepted27November2014;Published22December2014Copyright©2014Huei-PingHuangetal. This is an open access article distributed under the Creative Commons AttributionLicense,whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.

Assessment of the Urban Heat Island in Casa Grande, Arizona

Abstract The purpose of this study was to determine the spatial and temporal aspects of the urban heat island in the small, arid city of Casa Grande, Arizona. Temperature and dewpoint were collected through a combination of fixed stations and two mobile transect routes on four separate clear and calm nights during the period of 15–18 March 2004. A mobile transect on 18 March revealed a maximum heat difference of 4.7°C along an east-to-west route across the city, with a spatially interpolated temperature map illustrating warmest areas in the far eastern commercial corridor and cooler areas in the far southern and western regions of the city, consisting of rural agricultural fields. Wind speed at the Casa Grande Airport during transect times was seen to be a significant factor in determining intensity of heat differences. However, due to very light wind conditions encountered on all three nights (<2.5 m s−1), surface thermal properties and land cover may have played the largest role in determining heat island intensity. Thermal imagery taken of the area at a time similar to transect times (2125 LST) confirms the idea that surface thermal material properties may play a large role in determining heat island characteristics near the ground with the absence of strong winds.