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A bathymetric and geophysical survey was conducted
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over Medicine Lake in Siskiyou County, North Central California.
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A concurrent shallow-water sampling program was also conducted.
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JD 257 Tuesday, September 15
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travel from Redwood City to Medicine Lake
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JD 258 Wednesday, September 16
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Morning spent deploying Fast Eddie with Bimini top, cowling, and
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installing electronics. Boat launched about 1245 local (1945 GMT).
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Weather conditions excellent: v. light clouds, ~ 70-75_ F, sunny,
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light wind.
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SEACAT CDT instrument started logging approx. 1245 local; in the
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water 1300 GMT).
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First line consisted of a circumnavigation of the lake at 3.5 to
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4 knot. Ran into shallow water twice. NW end of the lake very broad
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and shallow. Returned to the dock at 1400. Deployed geopulse and back
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in the water at 2215Z. Finished surveying at 259/0000 (1700 PST).
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258/1945 start logging CDT.
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258/2000 leave dock, commence circumnavigation of lake; CDT in water
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258/2101 complete circumnavigation, arrive dock; CDT out of water
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258/2241 leave dock, testing reflection system; CDT back in water
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JD 259/0000 arrive dock; CDT out; end of day
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Problems with geopulse power supply limited reflection profiling.
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Changed out the power supply at the end of the day for the EG&G unit.
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JD 259 Thursday, September 17
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Weather conditions remain excellent: v. light clouds, ~ 70-75_ F,
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sunny, wind slightly greater than Wednesday and gusting 5-10 mph.
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Acquiring reflection data with geopulse and benthos streamer (one
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channel). A grid of east-west lines was generated for the survey
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area at a N-S spacing of ~50 meters. The "a" lines were north of
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the lake centerline; the "b" lines south. Steering the lines
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accurately proved problematic because of wind conditions and the
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filter response of the YONAV line-following algorithm.
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259/172800 start logging CDT
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259/173000 leave dock, commence deploying geopulse and benthos
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streamer
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259/173700 CDT in water
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259/174600 commence acquisition of EW lines
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259/182430 stop acquisition of EW lines
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259/183000 CDT out of water
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259/183300 CDT in water
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259/183700 continue acquisition of EW lines
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259/195400 stop acquisition of EW lines
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259/195500 CDT out of water
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259/200000 arrive dock, break for lunch
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259/212500 leave dock, CDT in water
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259/214900 continue acquisition of EW lines
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260/000400 complete acquisition of EW lines
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260/000500 CDT out of water
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JD 260 Friday, September 18
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Weather conditions remain excellent: v. light clouds, ~ 70-75_ F,
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sunny, wind calm.
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Acquiring reflection data with geopulse source, benthos streamer and
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Seistec receiver (two-channels). Survey lines run approximately
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NNE-SSW along arbitrary lines chosen by line of sight. Lines at
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eastern end of lake spaced closer (approx. 25-50 meters), at
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western end of lake wider (approx. 50-100 meters). CDT data not
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logged.
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260/173000 depart dock, deploying and tuning seistec at east end of lake
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260/181200 commence acquisition of NS lines
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260/211400 complete acquisition of NS line
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260/212000 arrive dock
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JD 261 Saturday, September 19
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Weather conditions remain excellent: v. light clouds, ~ 70-75_ F,
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sunny, wind calm.
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Sampling and temperature profiles acquired. Two sampling sites
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selected based on geophysical profiles:
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latitude longitude water depth profile day/time
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1. 41d 34.9911' -121d 35.4420' 37 m 259/1846
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2. 41d.34.8866' -121d 35.5590' 10 m 259/1916
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261/1715:21 41d 34.866' N 121d 35.582' W ---> dropping core 1 here
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261/1729:03 41d 34.880' N 121d 35.556' W ---> dropping again here
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261/1738:46 41d 34.986' N 121d 35.438' W ---> core site 2 drop here ~38m
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261/1801:34 41d 34.999' N 121d 35.419' W ---> drop long barrel core
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at 42.1 meter depth
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261/1824:55 41d 34.996' N 121d 35.465' W ---> site 2 core 10 first try
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261/1842:58 41d 34.991' N 121d 35.467' W ---> site 2 core 10 try 2
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261/1853:06 41d 34.971' N 121d 35.503' W ---> CDT drop here
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261/1857:42 41d 34.967' N 121d 35.526' W ---> start to pull up CDT here
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261/1858:46 41d 34.962' N 121d 35.526' W ---> CDT at surface
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261/1903:09 41d 34.995' N 121d 35.494' W ---> CDT drop 2 here
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261/1903:46 41d 34.994' N 121d 35.492' W ---> CDT on bottom-was not
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on bottom long enough
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261/1904:44 41d 34.992' N 121d 35.503' W ---> CDT at surface
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261/1904:54 41d 34.991' N 121d 35.505' W ---> CDT drop 3
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261/1905:49 41d 34.987' N 121d 35.512' W ---> CDT coming up
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261/1906:27 41d 34.985' N 121d 35.513' W ---> CDT at surface
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261/1915:53 41d 34.969' N 121d 35.449' W ---> drop core10 try 3
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JD 262 Sunday, September 20
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Demobilization and travel from Medicine Lake to Redwood City
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