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• and precipitation. Recovered data are defined as data that have passed quality assurance and review <br />as being valid reportable data. The following information summarizes the recovered and reported <br />data as percentages of total possible data quantities for the period of this report. Any missing data <br />were primarily due to instrument malfunctions. <br />Parameter Site 1 Percent Recove Site 2 Site 3 <br />Wind S eed 70.77 52.97 79.12 <br />Wind Direction 70.49 52.97 79.33 <br />Ambient Av Tem erasure 68.75 51.65 75.25 <br />Relative Humidi 43.93 - <br />Preci itation 53.12 -- <br />Wind <br />Data collected during the spring and summer quarters of 1977 indicate winds varied at the three <br />sites. Minimum wind speeds ranged from 0.6 mph to 1.4 mph. Maximum wind speeds ranged from <br />12.4 mpg to 19.7 mph. Mean wind speeds at the three sites were between 5.9 mph and 8.3 mph. <br />Hourly wind speed data show a consistent daily pattern that is almost identical for Sites 1 and 2. <br />The wind speed typically increases during the nighttime hours from about 7:00 p.m. Mountain <br />Standazd Time (KIST), reaching a peak speed of about 10.5 mph at about 7:00 a.m. the next <br />morning. At this time, the average wind speed drops over two or three hours to reach a morning <br />minimum speed of about 6.0 mph. It then rapidly increases to a second maximum of about 9.5 mph <br />by noon, with a subsequent slow decrease to reach a late afternoon minimum of about 5.0 mph. <br />The average diurnal variation in wind speed at Site 3 is strikingly different from that at Sites 1 and <br />2. At Site 3, wind speed remains relatively calm throughout the nighttime hours. Starting at about <br />8:00 am., wind speed increases to about 8.0 mph by 11:00 a.m. It stays at this level until about 3:00 <br />p.m. when it begins to decrease to its relatively constant nighttime level. Although the general <br />shape of the diurnal wind speed curve at Site 3 is markedly different from those for Sites 1 and 2, <br />there is a slight hint of an eazly morning (6:00 a.m.) relative maximum and a morning (8:00 a.m.) <br />relative minimum. However, this behavior is much less predominant than at Sites 1 and 2. <br />The explanation of this variation lies with the existence of a well established drainage flow down <br />the canyon from east to west. A relatively large basin to the east of the area (headwaters of the <br />North Fork of the Gunnison River) provides the volume of air to support this relatively intense flow <br />which is fimneled through the narrow canyon past the West Elk Mine site monitoring network. This <br />drainage flow is almost directly opposed to the geotropic or gradient flow which is typically from <br />the southwest. At sunrise, atmospheric heating reduces the horizontal pressure gradient which <br />supports the drainage flow. The wind speed at Sites 1 and 2 drops to relative minimum within <br />several hours under this influence. Above this low altitude, high speed drainage layer, the winds at <br />Site 3 remain relatively calm throughout the night and well into the morning hours. As discussed <br />later these relatively calm winds are less intense drainage winds themselves. <br />• The pronounced rise in the average wind speed at all sites during the late morning hours is <br />primarily due to the breakup of the surface-based inversion, or stable air, within the valley. As the <br />2.04-120 I/94 TRO5; B/99 TR7J; 6/95 PR06, 11/04 PRID <br />