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Why We Careor
Why We Go to Sea
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Who Uses the Data?• Shipboard personnel
• Vessel operations• Ocean deployments (buoys, CTDs, towed instruments)• Science during cruise
• Secondary users (not on cruise)• Ocean and atmosphere modelers• Satellite (and other remote) measurement community• Air-sea interaction researchers• Product developers (climate atlases, gridded fields)• Instrument developers
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Satellite Algorithm Development
Courtesy Darren Jackson, CIRES, NOAA/ESRL
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Satellite Validation
• Research vessel observations provide an independent assessment of biases in marine observations made by Earth-orbiting satellites (and other remote sensing platforms)
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Ocean Model Verification
Ship vs. ModelShip track over model salinity
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Air-Sea Flux Parameterization
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Real-Time Forecast ValidationData QC
http://catalog1.eol.ucar.edu/cgi-bin/dynamo/research/date_browse?dateUTC=20111116
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2007-1999 (28 cruises)
Where does the data go?
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How to Measure• Know what you want to measure…..parameter(s)• Know Temporal and Spatial scales• Know sensor characteristics
Accuracy, Precision, Range, ……
• Know the data acquisition system• Know the environment you will be working in
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What to Measure
• Meteorology• Wind directions and
speed• Air temperature• Humidity• Pressure• Rainfall• Radiation
• Oceanography• Sea temperature• Salinity
• Navigation• Latitude and longitude• Course over ground• Speed over ground• Speed relative to water• Heading
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Time Scales
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Time Scales
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Time Scales
monthly weekly…. daily
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Sampling RatesThe Nyquist-Shannon sampling theorem in general states a signal can be reconstructed fromits samples if the sampling frequency is greater than twice the highest frequency of the signal:also known as the Nyquist frequency.
Oversampling is often preferred as it:• Can aid in anti-aliasing• Can be used to increase resolution when using A/D convertors• Can also help reduce uncorrelated noise when averaging multiple samples.
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Accuracy / Precision Targets
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Accuracy/Precision
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An Introduction to Marine Meteorology
How does the Marine Environment differ from that over land?Homogeneity
Moisture sourceSurface frictionDiurnal cycles
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Surface Pressure• Pressure decreases with
increasing height above the surface• ~0.1 mb m-1 near the surface
• At a given location, pressure varies slowly
• Typical range is 990-1030 mb away from strong storms
• A diurnal atmospheric tide exists with a range of ±3 mb in the tropics
http://volney-bodley-weather-project.wikispaces.com/
http://samos.coaps.fsu.eduC % ms-1
Balloon Temperature, Humidity, and Winds
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Balloon Temperature, Humidity, and Winds
Speed
RH
Temp
Dir
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Precipitation/Clouds
24 hr Accumulated Rain Radar reflectivity
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Water Vapor 24 Oct 06Z
Satellite
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Total Precip1.3 to 5.6 mm
Time (UTC)
Precipitation/Clouds
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Precipitation
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Temperature
Air
Rain Rate
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Sea Temperature
4 Dec 1992Local Time
0
1
2
3
4
5
6
7
8
9
10
29.4 29.8 30.2 30.6 31 31.4 31.8 32.2
Temperature °C
Dep
th m 1400
1431
1641
1711
1819
1950
LocalTime
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Sea Temperature
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Radiation• Downwelling shortwave
radiation• Most common measurement
on a research vessel• Value ~1000 Wm-2 on clear day
at low latitude• Short-term variations
commonly identify passing clouds (or other shadows).
• Downwelling longwave (infrared) radiation • Emitted by clouds and
atmospheric gases• In tropics, ranges from 350-400
Wm-2
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Radiation
SW
LW
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EndLesson One
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