What is YoMaHa05

1
Global dataset of shallow and deep velocities
derived from Argo floats Hiroshi Yoshinari
(hy_at_hawaii.edu), Nikolai A. Maximenko
(nikolai_at_soest.hawaii.edu), Peter W. Hacker
(phacker_at_hawaii.edu) Asia-Pacific Data-Research
Center / International Pacific Research Center,
SOEST, University of Hawaii, Honolulu, USA.
YoMaHa05 Available!!

• What is YoMaHa05?
• Dataset of Deep Sea Surface Velocities and Its
  Errors
• Calculated from Argo Trajectory Data
• Coverage Time 1997-08-04 to 2006-01-05
• Space Whole World Ocean
• Status FULLY PUBLIC
• ACCESS NOW!

Applications
Deep
Sea Surface
Cycle Number
Cycle Number
http//apdrc.soest.hawaii.edu/projects/yomaha05/in
dex.html
Deep
Sea Surface
Zonal Vel. cm/s
Zonal Vel. cm/s

• Original Data Source Information
• All Argo Data at US-GODAE Site
• http//www.usgodae.org/ftp/outgoing/argo/
• Downloaded 2006-01-06
• Total 3039 Floats, 166683 Cycles

H.Yoshinari N.A.Maximenko P.W.Hacker
Meridional Vel. cm/s
Meridional Vel. cm/s
Deep
Sea Surface
Methods for Velocity Assessment

• Surface Velocities
• Velocity values and errors are assessed by
• linear regression of coordinates of ARGOS
  fixes.

• Deep Velocity (at Parking Level)
• Difference in float positions at Tn-1last
  Tnfirst is
• interpreted as displacement due to advection
• by deep currents at Zpark .
• Deep velocity values are time averages over the
• submerged part of the cycle.
• Error due to baroclinicity is based on deep and
• surface velocity values for the same cycle.

Magnitude of Vel. cm/s
Magnitude of Vel. cm/s
Deep
Sea Surface
Fig.1. Time-depth schematic of float cycle. Red
dots mark satellite fixes of the float at the sea
surface.
Spatiotemporal Distributions
Fig.6. Argo velocity statistics in 3 x 3 bins.
Left column is for parking level (larger than 750
dbar), right is for sea surface. Rows are number
of cycle falling into the bin (top, a, e), mean
zonal (b, f), meridional (c, g), velocity
components and magnitude of mean velocity
(bottom, d, h). Units of velocities are cm/s.
Deep velocities with the error larger than 2 cm/s
and surface velocities with the error larger than
15 cm/s are disregarded.

• Quasi-uniform Global Coverage at 1000 dbar
• Regional Coverage at 1500 2000 dbar
• Surface float velocities resemble SVP drifter
  observations and outline all
• main known surface currents.
• Strength of Antarctic Circumpolar Current is
  outstanding over the world
• ocean.

Fig.3. Distribution of YoMaHa05 deep velocity
data in 4 layers.
Fig.2. Annual distribution of Argo velocity
estimates in YoMaHa05.
1000 dbar 54, 1500 dbar 14, 2000 dbar 16

• Future Plans Upgrade toward YoMaHa06
• Improve Algorithms (e.g., Assess Inertial
  Oscillations Park et al., 2005, Errors in
• Parking Depth and Surface Arrival / Diving
  Times)
• Combine Surface Dynamic Ocean Topography
  Maximenko and Niiler, 2005 with
• Satellite Altimetry and Argo CTD-profiles and
  Velocities to Produce the 4-D Gridded
• Maps of Geostrophic Currents
• Validate against Direct Velocity Measurements
  (e.g., Current Meters, LADCP, etc.)

Velocities Characteristics
(a)
(b)
PDF of Deep Velocity
PDF of Deep Vel. Error
Fig.4. Probability density function (PDF) of (a)
deep velocity and (b) its error. Mean is (a)
5.3 cm/s, (b) 0.45 cm/s, respectively.

• References
• Maximenko, N. A., and P. P. Niiler, 2005 Hybrid
  decade-mean sea level with mesoscale resolution.
  In N. Saxena (Ed.) Recent Advances in
• Marine Science and Technology, 2004, pp.55-59.
  Honolulu PACON International.
• Park, J. J., K. Kim, and B. A. King, 2005
  Global statistics of inertial motions. Geophys.
  Res. Lett., 32, L14612, doi 10.1029/2005GL023258.
  
• Yoshinari, H., N. A. Maximenko, and P. W.
  Hacker, 2006 YoMaHa05 Velocity data assessed
  from trajectories of Argo floats at parking
• level and at the sea surface, IPRC Technical
  Note No.4, 20p.

(a)
(b)
PDF of Sea Surface Vel. Error
PDF of Sea Surface Velocity
Acknowledgements Yasushi Takatsuki, Takashi
Yoshida (JMA), Shinya Minato, Shigeki Hosoda,
Taiyo Kobayashi (IORGC/JAMSTEC), Jong Jin Park
(SNU), Shuiming Chen (SOEST/UH), Ann Thresher,
Rebecca Cowley (CSIRO), T V S Udaya Bhaskar
(INCOIS), You-Soon Chang (METRI),
Stephanie Contardo (BODC), Dan Webb (Webb Res.
Corp.), Claudia Schmid (AOML), Phill Sharfstein
(US-GODAE), and Sharon DeCarlo (APDRC).
Fig.5. PDF of (a) sea surface velocity and (b)
its error. Mean is (a) 28.7 cm/s, (b) 3.0
cm/s, respectively.