Arthur N. Samel

Development of a Regional Climate Model for U.S. Midwest Applications. Part I: Sensitivity to Buffer Zone Treatment

Abstract A regional climate model (RCM) is being developed for U.S. Midwest applications on the basis of the newly released Pennsylvania State University–NCAR Fifth-Generation Mesoscale Model (MM5), version 3.3. This study determines the optimal RCM domain and effective data assimilation technique to accurately integrate lateral boundary conditions (LBCs) across the buffer zones. The LBCs are constructed from both the NCEP–NCAR and ECMWF reanalyses to depict forcing uncertainties. The RCM domain was chosen to correctly represent the governing physical processes while minimizing LBC errors. Sensitivity experiments are conducted for the Midwest 1993 summer flood to investigate buffer zone treatment impacts on RCM performance. The results demonstrate the superiority of the buffer zone treatment that consists of the physically based domain choice and revised assimilation technique. Given this treatment, the RCM realistically simulates both temporal variations and spatial distributions in the major flood area ...

The Monsoon Rainband over China and Relationships with the Eurasian Circulation

Abstract Yearly variations in the observed initial and final dates of heavy, persistent monsoon rainband precipitation across China are quantified. The development of a semiobjective analysis that identifies these values also makes it possible to calculate annual rainband duration and total rainfall. Relationships between total rainband precipitation and the Eurasian circulation are then determined. This research is designed such that observed rainband characteristics can be used in future investigations to evaluate GCM simulations. Normalized daily precipitation time series are analyzed between 1951 and 1990 for 85 observation stations to develop criteria that describe general rainband characteristics throughout China. Rainfall is defined to be “heavy” if the daily value at a given location is greater than 1.5% of the annual mean total. Heavy precipitation is then shown to be “persistent” and is thus identified with the rainband when the 1.5% threshold is exceeded at least 6 times in a 25-day period. Fin...

Observed and GCM simulated decadal variability of monsoon rainfall in east China

Variability and associated mechanisms of summer rainfall over east China are identified and described using both observations and a general circulation model (GCM) simulation. The observations include two data sets: the 90-station, 1470–1988 annual drought/flood index and the 60-station, 1889–1988 monthly mean precipitation measurements. The GCM data set is a 100-year equilibrium simulation of the present climate. Spectra of the drought/flood index indicate decadal cycles which decrease from north (≈47 y) to south (≈21 y). Correlation coefficients show decadal variability in the relationship between index values along the Yangtse River valley and those over northeast and southeast China. Analysis of the measured data confirms this result; for example, the correlation was small during 1889–1918, but significantly negative during 1930–1959. When compared with precipitation measurements, the GCM better simulates monthly means and variances along the Yangtse River valley. Three distinct 30-year periods of interannual variability in summer rainfall are found over this area. During each period, rainfall is negatively correlated with spring surface temperature over a remote region and is identified with variations in a specific component of the east Asian monsoon circulation: (1) when Eurasian temperatures decrease, the thermal contrast across the Mei-Yu front increases and frontal rainfall intensities; (2) lower temperatures over the Sea of Japan/northwest Pacific Ocean are identified with enhanced easterly flow, moisture transport and rainfall; (3) when tropical east Pacific Ocean temperatures decrease, rainfall associated with the low latitude monsoon trough increases. Given that the GCM generates decadal changes in the relationship between the physical mechanisms, the east Asian monsoon and planetary general circulations and east China rainfall, future studies should focus on the predictability of these changes with the use of improved and much longer GCM simulations.

A Comparison between Observed and GCM-Simulated Summer Monsoon Characteristics over China

Abstract Observed rainfall over China and sea level pressure over Eurasia, two parameters that are closely associated with the east Asian summer monsoon, are compared with those simulated in a general circulation model (GCM). Observations are for the period 1951–1990 and include two datasets: a 160-station rainfall archive for China and a gridded sea level pressure record for Eurasia. The GCM dataset contains output from a 40-yr simulation with a mixed-layer ocean and greenhouse gas concentrations prescribed at 1990 levels. In both observations and the model simulation, empirical orthogonal function (EOF) analysis identifies two rainfall regions, the Yangtze River valley and southeast China, where interannual variability is large but relatively homogeneous. The locations of the model regions, however, are systematically shifted several degrees to the west. For each observed and model region, area-averaged summer rainfall anomalies are used to develop a 40-yr intensity index time series. Correlations betwe...

AMIP GCM Simulations of Precipitation Variability over the Yangtze River Valley

AbstractAnalysis of 26 simulations from 11 general circulation models (GCMs) of the Atmospheric Model Intercomparison Project (AMIP) II reveals a basic inability to simultaneously predict the Yangtze River Valley (YRV) precipitation (PrYRV) annual cycle and summer interannual variability in response to observed global SST distributions. Only the Community Climate System Model (CCSM) and L’Institut Pierre-Simon Laplace (IPSL) models reproduce the observed annual cycle, but both fail to capture the interannual variability. Conversely, only Max Planck Institute (MPI) simulates interannual variability reasonably well, but its annual cycle leads observations by 2 months.The interannual variability of PrYRV reveals two distinct signals in observations, which are identified with opposite subtropical Pacific SST anomalies in the east (SSTe) and west (SSTw). First, negative SSTe anomalies are associated with equatorward displacement of the upper-level East Asian jet (ULJ) over China. The resulting transverse circu...

A Geographic Information Systems Methodology for the Identification of Groundwater Recharge Areas in Waukesha County, Wisconsin

A Geographic Information Systems (GIS) based comparative methodology to delineate groundwater recharge areas was developed to identify recharge areas in Waukesha County, Wisconsin. Rapid growth in the county has increased fresh water demand, and groundwater levels have dropped between 45 and 60 meters. Recharge areas are particularly important to protect because misuse of these areas can lead to depletion of potable water supplies and increased groundwater contamination. Recharge potential mapping is an important step towards protecting regional groundwater resources. This study provides a method that can be implemented by local and regional planning boards to protect water resources. Precipitation, temperature, soil and land cover data were used to generate percolation, surface runoff and root-zone water capacity maps, which were used as proxies for recharge. These maps were then combined and ranked according to recharge potential, creating a recharge potential index suitable for land use planning decisions. Application of this method to Waukesha County, developed herein, indicates that the greatest source of recharge is the Kettle Moraine plateau in the western part of the county. Other regions with high recharge potential include those areas where interlobate moraines and drumlins are found at the surface.

MODIS Consistent Vegetation Parameter Specifications and Their Impacts on Regional Climate Simulations

AbstractA consistent set of Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation parameters, including leaf and stem area index (LAI and SAI, respectively), land-cover category (LCC), fractional vegetation cover (FVC), and albedo parameterization are developed, and their impacts on North American regional climate are evaluated based on 10-yr Climate–Weather and Research Forecasting Model (CWRF) simulations. As compared with the previous Advanced Very High Resolution Radiometer (AVHRR) set, MODIS LCC increases grassland and cropland fractions in the central Great Plains and Midwest, respectively. Evergreen needleleaf forest converts to mixed forest in the Southeast, and mixed forest converts to evergreen needleleaf in Canada. FVC decreases by 0.05–0.3 over the central Great Plains but increases by 0.1–0.35 over the northern Rocky Mountains, Canada, and the U.S. Southeast. MODIS LAI is less than AVHRR by 2–6, except in the central Great Plains, eastern Rocky Mountains, and central Mexico. LCC an...

China's rainfall interannual predictability : Dependence on the annual cycle and surface anomalies

Abstract Chinas rainfall interannual predictability is generally believed to depend upon the accurate representation of its annual cycle as well as teleconnections with planetary surface anomalies, including tropical east Pacific sea surface temperature and Eurasian snow and soil moisture. A suite of general circulation model (GCM) simulations is used to ascertain the existence of these relationships. First, a comparison of thirty 1980–88 Atmospheric Model Intercomparison Project (AMIP) GCM simulations shows no clear correspondence between model skill to reproduce observed rainfall annual cycle and interannual variability. Thus, accurate representation of either component does not ensure the realistic simulation of the other. Second, diagnosis of the 1903–94 and 1950–97 National Center for Atmospheric Research (NCAR) Community Climate Model, version 3 (CCM3), ensemble integrations indicates the existence of teleconnections in which spring planetary surface anomalies lead Chinas summer rainfall variation...

Evaluating the Influence of an Urban High School Reform Effort on College Readiness and Access Outcomes: A Quasiexperimental Cohort Study

It is widely accepted that postsecondary education has become a necessity for US youth. College access, however, has been found not to be equal for all. As a result, federally funded college-readiness programs, such as Gaining Early Awareness and Readiness for Undergraduate Programs (GEAR UP), have been established to increase the numbers of economically disadvantaged students with access to college. This quasiexperimental case study compared academic and nonacademic college-readiness indicators between cohorts of GEAR UP students and nonparticipants in 1 urban high school. Overall, cohorts of GEAR UP students outperformed their non-GEAR UP peers on all measures (grade-point average, attendance rate, behavior, graduation rate, and college enrollment) despite a dramatic demographic shift that led to greater proportions of educationally disadvantaged students in the GEAR UP cohorts.

An Introduction to Scientific Research and Methods in Geography by Daniel R. Montello and Paul C. Sutton

rightfully states that ‘‘When developers and public officials resort to privatization in order to achieve a more responsive design outcome . . . something is wrong with the existing parameters of subdivision codes and regulation’’ (p. 148). A major factor that may enhance the adoption of changes is technological. Three-dimensional modeling may allow not just public officials and planners the ability to envision development, they make it possible for individuals to critique proposed changes in their neighborhoods. Finally, BenJoseph calls for a more place-sensitive approach to planning: ‘‘The process of producing sets of standards, all practically identical in terms of a single ancestor, and applying them with disregard to place and locale, has more often than not created ubiquitous, unsympathetic spaces’’ (p. 189). Instead, site-specific and localized physical design is needed. The Code of the City places current planning issues in the historical context of rule and code in place making. Ben-Joseph is highly critical of the present form and the maze of standards questioning their relevancy. Strict obedience to standards has become almost unquestioned, but it is time to review and see whether they need to be amended. Standards are often too restrictive, blocking creative ideas and innovative thinking about neighborhoods and sustaining some unfavorable effects. For example, the inability to provide affordable housing in many developing countries is a result of adopting regulations inherited by colonial powers, which are inappropriate for their level of development. Standards are held accountable for low-density development and for preventing unconventional design practices that may result in more dense development. Issues raised in this book correspond to recurrent criticism of the layout of contemporary American cities in which low-density development, automobile dependency, and suburban sterility have gained the upper hand. Ben-Joseph believes that by changing details such as minimum lot size some of the ill-fated configurations often associated with sprawl could be reduced. He views the form of common-interest communities as a catalyst to change in subdivision standards, illustrating the shortcomings of many standards applied to typical subdivisions. In this book Ben-Joseph succeeds in drawing together related disciplines of architecture, planning, and urban development in an attempt to evaluate their roles in shaping cities. In an age that praises grand and global forces, the interpretation proposed by The Code of the City is innovative. Ben-Joseph, like Mies van der Rohe, thinks that God is the details and their amendment is fundamental for diverse and interesting urban spaces. In his pursuit of innovations and change it seems that Ben-Joseph has abandoned the potential function of the government in facilitating change. His assertion that the private sector is the envoy of change is justifiable; still the public sector has a major role in the revolution he suggests.