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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D21117, doi:10.1029/2005JD006657, 2006

Source regions of lower-tropospheric airflow trajectories for the lower peninsula of Michigan: A 40-year air mass climatology

Ryan P. Shadbolt

Department of Geography, Michigan State University, East Lansing, Michigan, USA


Eleanor A. Waller

Department of Geography, Michigan State University, East Lansing, Michigan, USA


Joseph P. Messina

Department of Geography, Michigan State University, East Lansing, Michigan, USA


Julie A. Winkler

Department of Geography, Michigan State University, East Lansing, Michigan, USA


Abstract

Airflow trajectories were used to create a long-term (40-year) air mass climatology for the lower peninsula of Michigan. The climatology provides a necessary baseline for evaluating the impact of changes in airflow on historical and potential future variations in temperature and precipitation. Five-day back trajectories were calculated four times per day at the 925 hPa level using wind data from the NCEP/NCAR reanalysis fields. A Geographic Information System (GIS) was used to manage and display the large (58,440) volume of trajectories. The analysis revealed spatially coherent airflow pathways, and six resulting air mass source regions were defined. Also evident were large monthly variations in the frequency of trajectories from the major source regions. A residence time analysis performed within a GIS proved to be an efficient and effective means for summarizing the trajectories. Finally, a comparison of the results presented here to those of previous climatological analyses suggests that the choice of methodology has considerable influence on identification of the primary source regions for a location.

Received 9 September 2005; accepted 23 June 2006; published 14 November 2006.

Keywords: airflow trajectory climatology; GIS; Great Lakes.

Index Terms: 3309 Atmospheric Processes: Climatology (1616, 1620, 3305, 4215, 8408); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 3364 Atmospheric Processes: Synoptic-scale meteorology; 1637 Global Change: Regional climate change; 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513).

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Citation: Shadbolt, R. P., E. A. Waller, J. P. Messina, and J. A. Winkler (2006), Source regions of lower-tropospheric airflow trajectories for the lower peninsula of Michigan: A 40-year air mass climatology, J. Geophys. Res., 111, D21117, doi:10.1029/2005JD006657.