Article Database

A Smart City Remembers Its Past

Abstract:

Integral to some conceptualizations of the “smart city” is the adoption of web-based technology to support civic engagement and improve information systems for local government decision support. Yet there is little to no literature on the “smartness” of gathering information about historic places within municipal information systems. This chapter provides three case studies of technologically augmented planning processes that incorporated citizens as sensors of data about historic places. The first case study is of SurveyLA, a massive effort of the city of Los Angeles to comprehensively survey over 880,000 parcels for historic resources. A second case study involves Motor City Mapping, an effort to identify the condition of buildings in Detroit, Michigan and a parallel historical survey conducted by volunteers. In Austin, Texas, a university-based research team designed a municipal web tool called the Austin Historical Survey Wiki. This chapter offers insights into these prior efforts to augment planning processes with “digitized memory,” web-based technology, and public engagement.

Atlanta’s urban heat island under extreme heat conditions and potential mitigation strategies

Abstract:

The urban heat island (UHI), together with summertime heat waves, foster’s
biophysical hazards such as heat stress, air pollution, and associated public health problems.
Mitigation strategies such as increased vegetative cover and higher albedo surface materials
have been proposed. Atlanta, Georgia, is often affected by extreme heat, and has recently
been investigated to better understand its heat island and related weather modifications. The
objectives of this research were to (1) characterize temporal variations in the magnitude of
UHI around Metro Atlanta area, (2) identify climatological attributes of the UHI under
extremely high temperature conditions during Atlanta’s summer (June, July, and August)
period, and (3) conduct theoretical numerical simulations to quantify the first-order effects
of proposed mitigation strategies. Over the period 1984–2007, the climatological mean UHI
magnitude for Atlanta-Athens and Athens-Monticello was 1.31 and 1.71C, respectively.
There were statistically significant minimum temperature trends of 0.70C per decade at
Athens and -1.79C per decade at Monticello while Atlanta’s minimum temperature
remained unchanged. The largest (smallest) UHI magnitudes were in spring (summer) and
may be coupled to cloud-radiative cycles. Heat waves in Atlanta occurred during 50% of the
years spanning 1984–2007 and were exclusively summertime phenomena. The mean
number of heat wave events in Atlanta during a given heat wave year was 1.83. On average,
Atlanta heat waves lasted 14.18 days, although there was quite a bit of variability (standard
deviation of 9.89). The mean maximum temperature during Atlanta’s heat waves was
35.85C. The Atlanta-Athens UHI was not statistically larger during a heat wave although
the Atlanta-Monticello UHI was. Model simulations captured daytime and nocturnal UHIs
under heat wave conditions. Sensitivity results suggested that a 100% increase in Atlanta’s
surface vegetation or a tripling of its albedo effectively reduced UHI surface temperature.
However, from a mitigation and technological standpoint, there is low feasibility of tripling albedo in the foreseeable future. Increased vegetation seems to be a more likely choice for
mitigating surface temperature.

Inclusion of urban landscape in a climate model: How can satellite data help?

Abstract:

rban regions, which cover only approximately
0.2% of the earth’s land surface, contain about half
of the human population (UNPD 2001).
Modeling urban weather and climate is critical for
human welfare, but has been hampered for at least
two reasons: i) no urban landscape has been included
in global and regional climate models (GCMs and
RCMs, respectively), and ii) detailed information
on urban characteristics is hard to obtain. With
the advance of satellite observations, adding urban
schemes into climate models in order to scale projections of global/regional climate to urban areas
becomes essential. Inclusion of urbanized landscape
into climate models was discussed in depth at the
fall American Geophysical Union (AGU) meeting of
2003 in the session entitled “Human-induced climate
variations linked to urbanization: From observations
to modeling,” which took place on 12 December 2003
in San Francisco, California (most of the presentations of this session can be found online at www.
atmos.umd.edu/~mjin/AGU03urban.html).

Climate change vulnerability assessment in Georgia

Abstract:

Climate change is occurring in the Southeastern United States, and one manifestation is changes in
frequency and intensity of extreme events. A vulnerability assessment is performed in the state of
Georgia (United States) at the county level from 1975 to 2012 in decadal increments. Climate change
vulnerability is typically measured as a function of exposure to physical phenomena (e.g., droughts,
floods), sensitivity to factors affecting the social milieu, and the capacity of a given unit to adapt to
changing physical conditions. The paper builds on previous assessments and offers a unique approach to
vulnerability analyses by combining climatic, social, land cover, and hydrological components together
into a unified vulnerability assessment, which captures both long-term and hydroclimatic events.
Climate change vulnerability indices are derived for the 1980s, 1990s, 2000s, and 2010s. Climate change
exposure is measured as: 1) departure of decadal mean temperature and precipitation from baseline
temperature and precipitation (1971e2000) using the United States Historical Climatology Network
version 2.5 and 2) extreme hydroclimatic hazards indicated by flood, heat wave and drought events.
Sensitivity and adaptive capacity are measured by well-established conceptualizations and methods built
derived from socioeconomic variables. Impervious surface and flood susceptibility area are also incorporated to account for place-based vulnerability.
Anomalies in temperature and precipitation with an overall trend towards drying and warming have
been observed. The anomalous cooling period in Georgia during the 1970e1980 period as well as the
post-1980 warm-up have been captured with a clearly established increase in extreme hydroclimatic
events in recent decades. Climate vulnerability is highest in some metropolitan Atlanta and coastal
counties. However, the southwestern region of Georgia, and part of the rural Black belt region are found
to be especially vulnerable to climate change.

On the relationship between the premonsoonal rainfall climatology and urban land cover dynamics in Kolkata city, India

Abstract:

Empirical and modelling studies show that urbanization can have an impact on the environment. Relatively
few studies have investigated urban effects on precipitation in India or other developing countries experiencing rapid
urbanization. Furthermore, most precipitation-related studies for India focus on monsoonal rainfall. However, premonsoonal
periods (March–May) account for 12–14% of the annual cumulative rainfall in eastern India. The majority of premonsoonal
rainfall (PMR) is convective and caused by mesoscale forcing, which may include urban effects. In this study, the area
under scrutiny is a large urban area in eastern India, Kolkata city. Herein, our goal was to (1) produce a comprehensive
characterization of historical land cover dynamics associated with the Kolkata megalopolis, (2) provide a spatio-temporal
climatology of PMR in the Kolkata region, and (3) identify possible associations between Kolkata’s land cover and PMR.
The analysis shows that the rate of change of urban land cover has increased by 50% compared to the period prior to India’s
independence in 1947. A multi-scalar time series analysis with Mann–Kendall statistics indicated statistically significant
increasing trends in rainfall over the last 50 years for two Kolkata stations and a nearby downwind station. Furthermore,
there was no significant trend for cumulative PMR in less urbanized stations, the country of India, or the East Gangetic
region. This finding suggests that the anomaly of the three stations, showing increasing trends in PMR, could be the effect
of urban land cover change. Copyright  2011 Royal Meteorological Society

Structure of Florida thunderstorms using high-altitude aircraft radiometer and radar observations

Abstract:

This paper presents an analysis of a unique radar and radiometer dataset from the National Aeronautics and
Space Administration (NASA) ER-2 high-altitude aircraft overflying Florida thunderstorms on 5 October 1993
during the Convection and Moisture Experiment (CAMEX). The observations represent the first ER-2 Doppler
radar (EDOP) measurements and perhaps the most comprehensive multispectral precipitation measurements
collected from a single aircraft. The objectives of this paper are to 1) examine the relation of the vertical radar
reflectivity structure to the radiometric responses over a wide range of remote sensing frequencies, 2) examine
the limitations of rain estimation schemes over land and ocean backgrounds based on the observed vertical
reflectivity structures and brightness temperatures, and 3) assess the usefulness of scattering-based microwave
frequencies (86 GHz and above) to provide information on vertical structure in the ice region. Analysis focused
on two types of convection: a small group of thunderstorms over the Florida Straits and sea-breeze-initiated
convection along the Florida Atlantic coast.
Various radiometric datasets are synthesized including visible, infrared (IR), and microwave (10–220 GHz).
The rain cores observed over an ocean background by EDOP, compared quite well with elevated brightness
temperatures from the Advanced Microwave Precipitation Radiometer (AMPR) 10.7-GHz channel. However,
at higher microwave frequencies, which are ice-scattering based, storm evolution and vertical wind shear were
found to be important in interpretation of the radiometric observations. As found in previous studies, the icescattering region was displaced significantly downshear of the convective and surface rainfall regions due to
upper-level wind advection. The ice region above the rain layer was more opaque in the IR, although the 150-
and 220-GHz brightness temperatures Tb approached the IR measurements and both corresponded well with the
radar-detected ice regions. It was found that ice layer reflectivities and thicknesses were approximately 15 dBZ
and a few kilometers, respectively, for detectable ice scattering to be present at these higher microwave frequencies.
The EDOP-derived rainfall rates and the simultaneous microwave Tb’s were compared with single-frequency
forward radiative transfer calculations using a family of vertical cloud and precipitation water profiles derived
from a three-dimensional cloud model. Over water backgrounds, the lower-frequency emission-based theoretical
curves agreed in a rough sense with the observed radar rainfall rate–Tb data points, in view of the uncertainties
in the measurements and the scatter of the cloud model profiles.
The characteristics of the ice regions of the thunderstorms were examined using brightness temperature differences DTb such as Tb (37 GHz) 0 Tb (220 GHz). The DTb’s (150–220, 89–220, and 37–86 GHz) suggested
a possible classification of the clouds and precipitation according to convective cores, elevated ice layers, and
rain without significant ice above the melting layer. Although some qualitative classification of the ic

Urbanization: Impacts on clouds, precipitation, and lightning

Abstract:

Precipitation variability and water cycle changes affect many components of the Earth’s natural and human system. Further, it is clear that natural and anthropogenic activities can perturb key components of the hydrological cycle. Understanding and quantifying such changes is vital for a range of meteorological, hydrological, ecological, and climate problems. In an era of heightened sensitivity concerning climate change, the primary discussion of cloud‐precipitation variability has been linked to greenhouse gas emissions. Scientific literature has presented theories and observational studies describing how urbanization influences convective processes and cumulative precipitation. The urban environment’s (i.e., its land use, aerosols, thermal properties) impact on precipitation will be increasingly vital to climate diagnostics and prediction, global water and energy cycle assessment and prediction, weather forecasting, freshwater resource management, agriculture, and urban planning. This chapter presents a contemporary review of findings and methods related to urban effects on precipitation and related convective processes, particularly lightning. Herein, we present historical and current literature, prevailing hypotheses, critical analysis of challenges facing the research topic, and recommendations for the future.

Risks, health consequences, and response challenges for small-island-based populations: observations from the 2017 Atlantic hurricane season

Abstract:

t
The intensely active 2017 Atlantic basin hurricane season provided an
opportunity to examine how climate drivers, including warming oceans and rising seas,
exacerbated tropical cyclone hazards. The season also highlighted the unique
vulnerabilities of populations residing on small island developing states (SIDS) to the
catastrophic potential of these storms. During 2017, 22 of the 29 Caribbean SIDS were
affected by at least one named storm and multiple SIDS experienced extreme damage.
This paper aims to review the multiplicity of storm impacts on Caribbean SIDS
throughout the 2017 season, explicate the influences of climate drivers on storm
formation and intensity, explore the propensity of SIDS to sustain severe damage and
prolonged disruption of essential services, document the spectrum of public health
consequences, and delineate the daunting hurdles that challenged emergency
response and recovery operations for island-based, disaster-affected populations.

Megapolitan political ecology and urban metabolism in Southern Appalachia

Abstract:

Drawing on megapolitan geographies, urban political ecology, and urban
metabolism as theoretical frameworks, this paper theoretically and empirically explores
‘megapolitan political ecology.’ First, we elucidate a theoretical framework in the context
of southern Appalachia and, in particular, the Piedmont megapolitan region. We argue that
the megapolitan region is a useful scale through which to understand urban metabolic
connections that constitute this rapidly urbanizing area. We also push the environmental
history and geography literature of the US South and southern Appalachia to consider the
central role urban metabolic connections play in the region’s pressing social and
environmental crises. Secondly, we empirically illuminate these human and non-human
urban metabolisms across the Piedmont megapolitan region using data from the Coweeta
Long-Term Ecological Research program. We especially highlight here a growing ‘Ring of
Asphalt’ that epitomizes several developing changes to patterns of metabolism. We
conclude by suggesting that these Coweeta LTER data show that changing urban
metabolism, ranging from flows of people to flows of water, poses a complicated problem
for regional governance and vitality in the future.

Rainfall morphology in Florida convergence zones: A numerical study

Abstract:

Central Florida is the ideal test laboratory for studying convergence zone–induced convection. The region regularly experiences sea-breeze fronts and rainfall-induced outflow boundaries. The focus of this study is convection associated with the commonly occurring convergence zone established by the interaction of the sea-breeze front and an outflow boundary. Previous studies have investigated mechanisms primarily affecting storm initiation by such convergence zones. Few have focused on rainfall morphology, yet these storms contribute a significant amount of precipitation to the annual rainfall budget. Low-level convergence and midtropospheric moisture have been shown to be correlated with rainfall amounts in Florida. Using 2D and 3D numerical simulations, the roles of low-level convergence and midtropospheric moisture in rainfall evolution are examined.

The results indicate that area- and time-averaged, vertical moisture flux (VMF) at the sea-breeze front–outflow convergence zone is directly and linearly proportional to initial condensation rates. A similar relationship exists between VMF and initial rainfall. The VMF, which encompasses depth and magnitude of convergence, is better correlated to initial rainfall production than surface moisture convergence. This extends early observational studies that linked rainfall in Florida to surface moisture convergence. The amount and distribution of midtropospheric moisture affects how much rainfall associated with secondary cells develop. Rainfall amount and efficiency varied significantly over an observable range of relative humidities in the 850–500-mb layer even though rainfall evolution was similar during the initial or “first cell” period. Rainfall variability was attributed to drier midtropospheric environments inhibiting secondary cell development through entrainment effects. Observationally, a 850–500-mb moisture structure exhibits wider variability than lower-level moisture, which is virtually always present in Florida. A likely consequence of the variability in 850–500-mb moisture is a stronger statistical correlation to rainfall as noted in previous observational studies.

The VMF at convergence zones is critical in determining rainfall in the initial stage of development but plays a decreasing role in rainfall evolution as the system matures. The midtropospheric moisture (e.g., environment) plays an increasing role in rainfall evolution as the system matures. This suggests the need to improve measurements of depth and magnitude of convergence and midtropospheric moisture distribution. It also highlights that the influence of the environment needs to be better represented in convective parameterizations of larger-scale models to account for entrainment effects.