Jay R. Harman

Winter Cyclones and Circulation Patterns on the Western Great Lakes

The climatology of winter cyclones crossing the western Great Lakes was investigated. Data concerning storm strength, place of origin, and surface and 500 mb level synoptic characteristics were obtained from the months of October through February, 1955–1976, for 469 cyclones. November cyclones had the lowest mean pressure and strongest pressure gradient of the 5 months examined, but cyclonic frequencies were greatest in December and January. In all months, cyclones originating in the southwestern United States were significantly deeper than storms of northern origins, and these cyclones crossed the western Lakes most frequently in November. In November, cyclogenesis in the southwest was related to departures of the observed flow from the mean monthly mid-tropospheric circulation with trough development over the west. Yearly variations in the number of severe November cyclones were related to differences of mean monthly 500 mb flow.

Climate and Vegetation in Central North America: Natural Patterns and Human Alterations

The characteristic patterns of climate and natural vegetation in central North America are strongly interrelated and result from an atmospheric circulation system that responds to both global and continental scale mechanisms. Climatic patterns arise in the region between the Rocky Mountains and the Great Lakes or Mississippi River from the interactions between two major components of the global atmospheric circulation system: the tropical Hadley Cell, and the extratropical, upper-level Westerlies. The Westerlies, particularly, are influenced and steered by thermal inequalities over the earth’s surface as well as the terrain barriers such as the Rocky Mountain Cordillera. In addition, both the Hadley Cell and the Westerlies shift north and south on an annual cycle.

SYNOPTIC CLIMATOLOGY: THEMES, APPLICATIONS, AND PROSPECTS

Synoptic climatology is defined as the study of climates from the viewpoint of their atmospheric circulation components and emphasizes the connection between circulation, weather phenomena, and climatic differentiation. The field is seen as having developed rapidly, starting in the 1950s, in both meteorology and geography. Some important historical developments are summarized and we conclude with an assessment of future prospects. [Key words: synoptic climatology, atmospheric circulation, climates.]

THE NORMAL SUMMER-AUTUMN PRECIPITATION DECLINE IN THE NORTH-CENTRAL UNITED STATES

Surface and upper atmospheric data collected for August and October for the period 1969–1979 from the central United States were analyzed for evidence of mechanisms producing the normal decline of ...

Environmental Ethics and Coastal Dunes in Western Lower Michigan: Developing a Rationale for Ecosystem Preservation

Abstract The management of shoreline dune systems in the Great Lakes has long been contested. Some parties have viewed them as a consumable resource, while others have argued for their preservation. These differences arise out of con-trasting views about both the value of the dunes as well as which kind of value overrides which. Some of their value has been seen as residing in their geomorphic uniqueness, an interpretation based on older (largely qualitative) field studies that suggest they are fossil landscape features. Recent findings indicate, however, that most dunes arise from episodic, ongoing processes. Contradictory management implications of this new research can flow either from the heightened empirical uncertainty it has created (which gestures toward preservation) by undermining the prevailing views of dune development and chronology, or from diminished-value arguments it has stimulated (which lessen constraints on consumptive use) by calling into question older views about the geomorphic uniqueness of the dunes. Faced with such a dilemma, for practical guidance on the management of special places we turn to environmental ethics literature, where we find that long-standing disputes about where value in the environment is seated provide little further guidance. Accordingly, we propose that the ethical principle of respecting what others value out of respect for them be applied in such matters. This principle is consistent with both moral intuition and widespread practice, and its application in environmental policy would bypass some of the recalcitrant questions left open by other analyses of environmental value. With certain qualifications, this view then supports preservation of special places like lakeshore dunes regardless of the signal from empirical certainty or uncertainty or disagreement about just why valued places are valuable in the first place.

A SYNOPTIC CLIMATOLOGY OF MOISTURE STRESS GRADIENTS IN THE WESTERN GREAT LAKES REGION

Surface pressure distributions and 500 millibar flow patterns are identified for summer season days with a moisture stress gradient across the western Great Lakes region that may be related to the location of the prairie-forest ecotone. Results indicate that days with moisture stress gradients are a characteristic feature of the summer climate in the area and that these days are associated with unique, nonrandom groupings of mid-tropospheric flow patterns. SW-NE and W-E stress gradients, those that appear to contribute most to defining and reinforcing the location of the ecotone, occur most frequently, and the modal 500-mb flow direction for these transect groups, an azimuth of 290°, is the same as the mode for the entire population of summer season flow directions. We conclude that the modal mid-tropospheric circulation of the summer season plays a significant role in determining the surface weather conditions that regulate the most common moisture stress patterns within the western Great Lakes region.

“Whither Geography?” Concluded: Is Geography Graduate Education Missing One of Its Targets?*

Abstract As geographers working in a professional capacity, many of us engage in scholarly research. Unless it is self-supporting and the results are kept confidential, this activity requires that we strike relationships with various “third parties,” constituencies who lie outside of the usual two-party, researcher–subject relationship but are unavoidably drawn in because they help support our work, use our findings, or bear their practical consequences, good or bad. How (and why) should we relate to them? One option is to maximize all (positive) types of third-party impacts by intentionally pursuing scholarship that benefits the greatest range of constituencies. If this approach is desirable from the perspective of the discipline, science, and society, we have good reason to promote it, but how? Doing so with artificial (extrinsic) incentives or imposed mandates raises questions about academic freedom. Alternatively, recasting questions about which scholarly line to investigate into ethical terms that emphasize such third-party issues might, in and of itself, promote greater prior reflection and perhaps broader outcomes. Such outcomes seem even more likely when reflection on the objective question of third-party interests is accompanied by a nurtured compassion for parties who are less well off. The pedagogical implications of these conclusions will be explored. *I would like to thank several anonymous reviewers, whose comments on an early draft of this manuscript helped strengthen it, and the Department of Geography, Michigan State University, where a reduced teaching load for one semester helped me revise this piece in a timely manner.

CLIMATOLOGICAL CHARACTERISTICS OF SPRINGTIME LOWER TROPOSPHERIC AIRFLOW OVER CENTRAL AND EASTERN NORTH AMERICA

A climatology of springtime lower tropospheric airflow, as represented by 850 hPa observed winds and 1000 hPa geostrophic winds, is presented for central and eastern North America. The climatology is based on twice-daily grid-point values for 1969–1989 from the operational analyses for the Northern Hemisphere prepared by the USA National Weather Services National Meteorological Centre. Sixteen-point wind roses are used to show the spatial and temporal distributions by direction category of wind frequency, average speed, and wind run. These analyses are supplemented by resultant wind vector and streamline maps for each month. Evident in the climatological distributions is the declining strength of the circulation from March to May, the northward migration and strengthing of the North Atlantic subtropical anticyclone in late spring, and the nocturnal strengthening and veering of southerly airflow over the southern Great Plains. Additionally, areas of cyclonic and/or anticyclonic resultant flow correspond well with earlier identified centres of cyclogenesis and anticyclogenesis. The results presented here may provide a useful climatological baseline for future studies involving lower tropospheric airflow.

Soil, subsoil, and forest composition in south-central Michigan, USA.

Although soil texture is an important predictor of upland forest composition in southern Michigan, the relationship in some areas is weak and other environmental factors may exert stronger control on species composition. One of these may be concealed subsoil lithology where coarse-textured glaciofluvial sediments are buried beneath finer-textured till. Samples of forest composition, soil, and subsoil characteristics from 48 less-disturbed woodlots in the south-central Lower Peninsula reveal that upland oaks and hickories are predominant where the till veneer is thin and sand and gravel are relatively near the surface. Where till is relatively thick and outwash is deeply buried, woodlot composition is sugar maple-beech. In each of these cases, soil texture is unrelated to stand composition. The likely effect of buried near-surface glaciofluvial sediments is moisture stress such that xeric species dominate these drier sites. The influence of subsoil on forest geography is a significant new finding with rega...