Scripps High Resolution XBT Network: QA/QC Procedures. Lisa Lehmann, Dean Roemmich , and Glenn Pezzoli Scripps Institution of Oceanography GTSPP Workshop, Oostende Belgium May 2010. Outline. Data quality begins at sea. Delayed-mode quality control. Future directions.
Scripps High Resolution XBT Network: QA/QC Procedures
Lisa Lehmann, Dean Roemmich, and Glenn Pezzoli
Scripps Institution of Oceanography
GTSPP Workshop, Oostende Belgium
The SIO High Resolution XBT Program deploys 6000 XBTs per year, as part of the global HRX partnership.
Eastern subtropical North Pacific: Drop 44 is quite different from 43 and earlier profiles. A re-drop (45) about 2 km along-track shows that 44 is ok, with subsequent drops “filling in” the transition.
Tropical North Pacific:
Drop 182 is quite different from 181 and earlier profiles. A re-drop (183) about 2 km along-track confirms that 182 is bad.
Important to understand cruise and weather conditions. Eastern subtropical North Pacific: Drop 001 (in gray) shows record rain runoff. If ship-rider did not document that fact, I would have considered the surface suspect. The following profiles also show deeper mixed layer than in previous transects, likely due to huge swells in area during this time.
PX37 South, January 2010
False splashes are caused by ground faults in the wiring. These are generally caused by moisture in the equipment. Our ship-riders are trained to detect and fix problems as they occur, thus ensuring a cleaner dataset. We run any profiles with false splash detects through an operator driven filter which shows the raw ascii data and allows us to choose the actual splash. Then we can overlay the re-created profile with it’s neighbors and climatology to determine if the data is good.
Profile 44 (red) shows false splash detect
Profile 44 (red) after removing false splash
Important to realize best source of QC information for each profile in high resolution sampling is the neighboring profiles.
This sequence shows the temperature inversion at the base of the mixed layer just north of Fiji.
PX09 Oct 2009
This cluster of neighbors in the Kuroshio illustrates how closely spaced profiles (~15 km apart) reveal the highly structured character of the temperature field in a strong current.
PX44 January 2009
We use a climatology developed from the HRX transects for many checks. Here it is used to determine where profile 247 (Top, green) went bad.
Profile 247 (Bottom, black) is
compared to climatology. It appears to have gone bad at 600 m, where it veers abruptly warm to climatology.
We can view “buddies” of a profile individually to see if a particular feature has been see in the past (or future). Profile 170 (Top, red). Is that an inversion or wirestretch at 580m?
Profile 170 (bottom, black)
appears to veer warm to
PX10 January 2004
220 profiles used to create
PX10 January 2004-Profile 170 (black, all 3 figures) is shown with buddies from different cruises. We can find many profiles that match it very well over time. We’ll call this a PIA (Inversion Probable)
Shown with PX10 February 1994
Shown with PX10 April 2003
Shown with PX10 August 1995
If a feature (top: profile 027 in black, bottom: profile 036 in black) is not present in neighboring profiles and does not have a close geographical buddy in past cruises, then consider regional oceanographic features.
PX37 Feb 2008
PX37 Nov 2008
This (top, right) and other previous transects show confirmed eddies in the region of the previous two unconfirmed profiles. Therefore we consider the two profiles on the previous slide as good data (class 1).
PX37 Jul 1996
At right, a very similar feature, occurring nearby in a CTD transect at 37oN, 128oW, was described as a California Undercurrent eddy by Cornuelle et al (2000, JGR, 105, 1227-1243.)
All ship tracks have some variability.
PX37/10/44: 72 transects 1991 - 2009
Argo 6-year mean temperature at 600 dbar