Xylem SonTek River Surveyor M9, Системное руководство

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SonTek, a Xylem brand
RiverSurveyor S5/M9 System Manual (February 2013)
153
highly accurate flow measurements in our rivers and oceans and with more ADP data being
used for measurements other than velocity such as discharge and bathymetry, the need for ap-
plying sound speed corrections to ADP data is increasing.
Sound speed corrections improve the accuracy of ADP discharge calculations by increasing the
accuracy of the river cross-sectional area. Accurate sound speed measurements at the ADP
transducer face are important for velocity measurement accuracy. The fast response of the
CastAway thermistor eliminates the need for waiting for the ADP thermistor to equilibrate to wa-
ter temperature. Measuring temperature and conductivity at the surface allows for the most ac-
curate sound speed equation to be used in the velocity calculations.
CastAway CTD and RiverSurveyor Integration
The CastAway is a small sophisticated CTD that provides a turnkey solution for applying sound
speed corrections to RiverSurveyor measurements by integrating seamlessly with RiverSurvey-
or Live 3.0 and RiverSurveyor Stationary Live 2.0. Collecting sound speed profiles is simple
with the CastAway: it can be lowered by hand, requires no preprogramming, and after a cast au-
tomatically transfers data to your PC. A built in GPS marks the location and timestamp of the
sound speed profile and also allows the software to automatically select which profile to apply to
the discharge calculation. In the software, there is also a summary page that displays tempera-
ture, salinity and sound speed information from the CastAway (Fig. 138).
Figure 138. CastAway CTD Summary Information Tab.
The RiverSurveyor Live (v3.0 or later) software adds a marker for the CastAway profile location
on the center ship track plot (Fig. 139). The GPS coordinates must be changed to
UTM Dis-
play by right-clicking on the track plot. Open the Processing Toolbox to select the CastAway
CTD Sound Speed Correction from the drop-down box. There are two options for applying the
CastAway sound speed correction to a discharge calculation: using ADP surface temperature
data and CastAway surface salinity, or using the full CastAway temperature and salinity profile.
The correction can be done manually by selecting the appropriate .ctd file or automatically. If