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5.0 1983 CROSS APPALACHIAN TRACER EXPERIMENT<br />

5.1 DESCRIPTION OF THE 1983 CROSS APPALACHIAN TRACER EXPERIMENT<br />

A series <strong>of</strong> tracer test field experiments were conducted between September 18 <strong>and</strong> October<br />

29, 1983 over <strong>the</strong> nor<strong>the</strong>astern U.S. <strong>and</strong> sou<strong>the</strong>astern Canada (Ferber et al., 1986; Draxler et<br />

al., 1988). The Cross‐Appalachian Tracer Experiment (CAPTEX) consisted <strong>of</strong> 5 tracer releases<br />

from Dayton, Ohio <strong>and</strong> 2 tracer releases from Sudbury, Ontario. Each release was independent<br />

<strong>of</strong> <strong>the</strong> o<strong>the</strong>rs <strong>and</strong> was conducted when <strong>the</strong> forecast was for <strong>the</strong> tracer to pass through <strong>the</strong><br />

center <strong>of</strong> <strong>the</strong> sampling network. Samplers were placed at a variety <strong>of</strong> locations in <strong>the</strong> nor<strong>the</strong>ast<br />

U.S. <strong>and</strong> sou<strong>the</strong>ast Canada to distances <strong>of</strong> about 1,000 km from Dayton. Although synoptic<br />

meteorological conditions were similar between releases at each location, <strong>the</strong>re were large<br />

differences in <strong>the</strong> spatial concentration patterns, from narrow to wide. There was even a case<br />

<strong>of</strong> <strong>the</strong> tracer plume passing over <strong>the</strong> samplers without mixing to <strong>the</strong> surface.<br />

The <strong>CALPUFF</strong> LRT modeling system was evaluated for various model configurations <strong>and</strong><br />

meteorological inputs using two <strong>of</strong> <strong>the</strong> five CAPTEX tracer release experiments:<br />

CTEX3: The third CAPTEX tracer release occurred on October 2, 1983 where a tracer was<br />

released from Dayton, Ohio for two hours between <strong>the</strong> hours <strong>of</strong> 1400 <strong>and</strong> 1600 LST with a<br />

release rate <strong>of</strong> 18.611 g/s.<br />

CTEX5: The fifth CAPTEX tracer release occurred during <strong>the</strong> end <strong>of</strong> October with a two<br />

hour tracer release from Sudbury, Ontario between hour 23 on October 25, 1983 <strong>and</strong> hour<br />

01 on October 26, 1983 with a release rate <strong>of</strong> 16.667 g/s.<br />

Figure 5‐1 displays <strong>the</strong> locations <strong>of</strong> <strong>the</strong> two tracer release sites <strong>and</strong> <strong>the</strong> tracer sampling network<br />

for <strong>the</strong> CAPTEX tracer field experiments. Also shown in Figure 5‐1 are <strong>the</strong> <strong>CALPUFF</strong>, CALMET<br />

<strong>and</strong> MMIF modeling domains.<br />

This section describes <strong>the</strong> evaluation <strong>of</strong> <strong>the</strong> <strong>CALPUFF</strong> LRT dispersion model using <strong>the</strong> CTEX3 <strong>and</strong><br />

CTEX5 field experiments using numerous sensitivity tests with alternative meteorological<br />

inputs. Appendices A <strong>and</strong> B present <strong>the</strong> evaluation <strong>of</strong> <strong>the</strong> MM5 <strong>and</strong> CALMET sensitivity<br />

simulations using surface meteorological observations for <strong>the</strong>, respectively, CTEX5 <strong>and</strong> CTEX3<br />

experiments. Appendix C presents <strong>the</strong> evaluation <strong>of</strong> six LRT dispersion models using <strong>the</strong> CTEX3<br />

<strong>and</strong> CTEX5 field studies <strong>and</strong> common MM5 meteorological inputs.<br />

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