Article Database

Aerosols and associated precipitation patterns in Atlanta

Abstract:

The role of aerosol concentrations on summer precipitation was examined in Atlanta, Georgia for the
period 2003–2004. Each day of the week was examined to ascertain their aerosol concentrations.
Thursday had the highest median 2.5 mm particulate matter (PM 2.5) concentrations at two of three
Environmental Protection Agency stations. Monday and Thursday had the largest area of significantly
different precipitation when compared to other days of the week. All but the southeast quadrant of the
metropolitan area had a significant difference in precipitation on high versus low aerosol days. High
aerosol days had greater instability (higher average convective available potential energy and lower
convective inhibition), and a slightly more shallow mixing layer when compared to low aerosol days.
Most of metropolitan Atlanta had higher precipitation amounts on high aerosol days and was significantly different from low aerosol days.

Development of a parameterization for simulating the urban temperature hazard using satellite observations in climate model

Abstract:

Urban surface temperature is hazardously higher than surrounding regions
(so-called urban heat island effect UHI). Accurately simulating urbanization-induced
temperature hazard is critical for realistically representing urban regions in the land surface-atmosphere climate system. However, inclusion of urban landscapes in regional or
global climate models has been overlooked due to the coarse spatial resolution of these
models as well as the lack of observations for urban physical properties. Recently, National
Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Moderate
Resolution Imaging Spectroradiometer (MODIS) observations illustrate important urban
physical properties, including skin temperature, surface albedo, surface emissivity, and leaf
area index, It is possible to identify the unique urban features globally and thus simulate
global urban processes. An urban scheme is designed to represent the urban-modified
physical parameters (albedo, emissivity, land cover, roughness length, thermal and
hydraulic properties) and to include new, unique physical processes that exist in urban
regions. The urban scheme is coupled with National Center for Atmospheric Research
(NCAR) Community Land Model Version 2 (CLM2) and single column coupled NCAR
Community Atmosphere Model CAM2/CLM2 to assess the mechanisms responsible for
UHI. There are two-steps in our model development. First, satellite observations of albedo,
emissivity, LAI, and in situ observed thermal properties are updated in CLM2 to represent

A dynamic GIS–multicriteria technique for siting the NASA–Clark Atlanta Urban Rain Gauge Network

Abstract:

Because Atlanta, Georgia, is a model of rapid transition from forest/agriculture land use to urbanization, NASA and other agencies have initiated programs to identify and understand how urban heat islands (UHIs) impact the environment in terms of land use, air quality, health, climate, and other factors. Atlanta’s UHI may also impact the regional water cycle by inadvertent forcing of precipitating cloud systems. Yet, a focused assessment of the role of urban-induced rainfall in Atlanta has not been a primary focus of past efforts. Several observational and climatological studies have theorized that UHIs can have a significant influence on mesoscale circulations and resulting convection. Using spaceborne rain radar and a limited network of irregularly spaced, ground-based rain gauges, evidence that the Atlanta and Houston, Dallas, and San Antonio, Texas, urban areas may modify cloud and precipitation development was recently found.

To validate these recent satellite-based findings, it was determined that a higher density of rainfall gauges would be required for future work. The NASA-sponsored Study of Precipitation Anomalies from Widespread Urban Landuse (SPRAWL) seeks to further address the impact of urban Atlanta on precipitation variability by implementing a dense rain gauge network to validate spaceborne rainfall estimates. To optimize gauge location to a given set of criteria, a geographical information system (GIS) aided by a spatial decision support system (DSS) has been developed. A multicriteria decision analysis (MCDA) technique was developed to locate optimal sites in accordance to the guidelines defined by the World Meteorological Organization (WMO). A multicriteria analysis model for the optimization of prospective sites was applied to identify prime locations for the tipping-bucket rain gauges. The MCDA design required development of a spatial model by applying a series of linear programming methods, with the aid of spatial analytical techniques, in order to identify land sites that meet a particular set of criteria.

Urban surface temperature reduction via the urban aerosol direct effect: A remote sensing and WRF model sensitivity study

Abstract:

The aerosol direct effect, namely, scattering and absorption of sunlight in the atmosphere, can lower surface temperature by reducing surface insolation. By combining National Aeronautics and Space Administration (NASA) AERONET (AErosol RObotic NETwork) observations in large cities with Weather Research and Forecasting (WRF) model simulations, we find that the aerosol direct reduction of surface insolation ranges from 40–100Wm⁻², depending on aerosol loading and land-atmosphere conditions. To elucidate the maximum possible effect, values are calculated using a radiative transfer model based on the top quartile of the multiyear instantaneous aerosol data observed by AERONET sites. As a result, surface skin temperature can be reduced by 1°C-2°C while 2-m surface air temperature reductions are generally on the order of 0.5°C–1°C.

Assessment of satellite-based rainfall estimates in urban areas in different geographic and climatic regions

Abstract:

This paper presents an assessment of the 3B42 research version rainfall product
from NASA’s Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis
(TMPA). The study provides new results of TMPA data accuracy in urban areas and
highlights trends associated with the climatological indicators of temperature and relative
humidity in cities. Ten years (1998-2007) of TMPA data were analyzed for three case
study cities in the United States (Houston, Atlanta, and Las Vegas) and one in Korea
(Cheongju), representing semi-arid to humid climates. At each location, an urbanized river
basin and non-urbanized river basin were selected and comparisons between TMPA and
rain gage observations were made for recorded storm events in the study period, the largest
storm events by total depth, and selected hurricanes and topical storms. The results indicate
TMPA data match well with rain gage observations at all locations. TMPA is slightly
underestimated for semi-arid regions and overestimated for humid regions. The relative
magnitude of TMPA rain event accumulation compared to rain gage accumulation is noted
to be smaller for urbanized watersheds and high intensity events. The correlation of TMPA accuracy with temperature and relative humidity and the analysis of accuracy by season indicate TMPA is more accurate for convective rainfall events. This suggests a possible
linkage between the observed urban-modified temperatures, hypothesized enhanced convection, and improved TMPA accuracy in urban areas.

Insights into atmospheric contributors to urban flash flooding across the United States using an analysis of rawinsonde data and associated calculated parameters

Abstract:

Flooding is routinely one of the most deadly weather-related hazards in the United States, which highlights the need for more hydrometeorological research related to forecasting these hazardous events. Building upon previous literature, a synergistic study analyzes hydrometeorological aspects of major urban flood events in the United States from 1977 through 2014 caused by locally heavy precipitation. Primary datasets include upper-air soundings and climatological precipitable water (PW) distributions. A major finding of this work is that major urban flood events are associated with extremely anomalous PW values, many of which exceeded the 99th percentile of the associated climatological dataset and all of which were greater than 150% of the climatological mean values. However, of the 40 cases examined in this study, only 15 had PW values that exceeded 50.4 mm (2 in.), illustrating the importance of including the location-specific PW climatology in a PW analysis relevant to the potential for flash floods. Additionally, these events revealed that, despite geographic location and time of year, most had a warm cloud depth of at least 6 km, which is defined here as the layer between the lifting condensation level and the height of the −10°C level. A “composite” flood sounding was also calculated and revealed a characteristically tropical structure, despite cases related to tropical cyclones being excluded from the study.

Integration of lidar data into a coupled mesoscale–land surface model: A theoretical assessment of sensitivity of urban–coastal mesoscale circulations to urban canopy parameters

Abstract:

Urban–coastal circulations affect urban weather, dispersion and transport of pollutants and contaminants, and climate. Proper characterization and prediction of thermodynamic and dynamic processes in such environments are warranted. A new generation of observation and modeling systems is enabling unprecedented characterization of the three-dimensionality of the urban environment, including morphological parameters. Urban areas of Houston, Texas, are classified according to lidar-measured building heights and assigned typical urban land surface parameters appropriate to each classification. The lidar data were degraded from 1 m to the model resolution (1 km) with the goal of evaluating the impact of degraded resolution urban canopy parameters (UCPs) and three-dimensionality on the coastal–urban mesoscale circulations in comparison to typical two-dimensional urban slab approaches. The study revealed complex interactions between the sea breeze and urban heat island and offers a novel diagnostic tool, the bulk Richardson shear number, for identifying shallow mesoscale circulation.

Using the Advanced Research Weather Research and Forecasting model (ARW-WRF) coupled to an atmosphere–land surface–urban canopy model, the authors simulated a theoretical sea-breeze day and confirmed that while coastal morphology can itself lead to complex sea-breeze front structures, including preferred areas of vertical motion, the urban environment can have an impact on the evolution of the sea-breeze mesoscale boundary. The inclusion of lidar-derived UCPs, even at degraded resolution, in the model’s land surface representation can lead to significant differences in patterns of skin surface temperature, convergence, and vertical motion, which have implications for many aspects of urban weather.

Linkages between the built urban environment and earth’s climate system.

Abstract:

Although only 1.2% of the land area of the Earth is currently considered “urban,” the spatial coverage and density of cities is expected to rapidly increase in the near future. The United Nations estimates that by the year 2025, 60% of the world’s population will live in cities. Human activity in urban environments alters atmospheric composition; affects components of the water cycle; and modifies the carbon cycle and ecosystems.

However, our understanding of the effects of urbanization on the total Earth‐climate system is incomplete. The U.S. Climate Change Science Program (CCSP) strategic plan states that “…in a world that is more populated, urban, and interconnected than ever… A more integrated understanding of the complex interactions of human societies and the Earth System is needed.”

An Assessment Tool to Evaluate Student Learning of Engineering (Fundamental)

Abstract:

An Assessment Tool to Evaluate Student Learning of Engineering (Fundamental)While STEM subjects have traditionally been taught separately in K-12 schools the newinitiatives share a focus on integrated approaches to teaching STEM. For example, the recentlyreleased Next Generation Science Standards (NGSS) addressed the need for explicit integrationof science with engineering. Science teachers are expected to teach intersecting concepts andcore disciplinary science using scientific and engineering practices. One challenge that manyscience teachers face is the lack of measurement instruments for student learning required in theNGSS. Measuring the student understanding of engineering, connections between science andengineering, and engineering practices requires the development of new assessments. Thepurpose of this study was to develop, scale, and validate an assessment in engineering. The useof item response theory to assess item functioning was a focus of the study. The work is part ofa larger project focused on increasing student learning in STEM-related areas in Grades 4 – 8through an engineering design-based, integrated approach to STEM instruction and assessment.The test construction process began with an assessment development team of academicresearchers with collective expertise in engineering, science, and mathematics. Researcherswrote 21 multiple-choice items and content and face validity of the items were established byexpert review. Next the assessment was piloted in two waves with the goal of identifying finalversions of each assessment via item analyses and scaling students’ responses to produce anestimate of their proficiency. In the first wave the assessment was administered to a small groupof about 10-20 middle school students. The purpose was to obtain and analyze preliminary itemresponse data as well as obtain feedback on characteristics of the assessments and the testingenvironment that affected performance (e.g., readability, clarity of items). Based on informationprovided by wave 1 piloting the assessments were modified by the assessment developmentteam. In the second wave of piloting the revised assessments were administered toapproximately 150 students. Data from wave two were used to conduct extensive item analysesof the assessments. We initially performed a factor analysis of the data for each assessment formiddle school students. The goal of these analyses was to assess the likelihood that itemsrepresented a single underlying construct. The results suggested that a single (major) factorunderlies the assessment, a finding that was robust to different methods of factoring (principalaxis, maximum likelihood) and factor rotation (varimax, oblique). These results suggests that thegoal of constructing items for the assessment that reflected a single factor was generally met, andalso helped to justify the use of item response theory (IRT) to generate proficiency scores forstudents. Next the Rasch IRT model was fitted to the data for each item on each assessment toestimate that item’s ability to contribute to estimates of student proficiency. The Rasch modeladequately fits the data of all 21 items. In this presentation, we will present the development and reliability of the engineeringassessment and share the assessment tool with the participants.

Rehash Your Trash: An EngrTEAMS STEM Integration Recycling Curricular Module

Abstract:

WORKSHOP PROPOSAL FORM 2015 Annual ASEE K-12 Workshop on Engineering Education “Authentic Engineering: Representing & Emphasizing the E in STEM” Presented by Dassault Systems.