observations of mesoscale * ocean circulation: present and future
DESCRIPTION
Observations of Mesoscale * Ocean Circulation: Present and Future. Bo Qiu Dept of Oceanography University of Hawaii. Schematic of Satellite Altimetry. * mesoscale = 10s~100s km. A UH profiling float was being deployed from R/V Revelle in Kuroshio Extension, May ‘05. - PowerPoint PPT PresentationTRANSCRIPT
Observations of Mesoscale* Ocean
Circulation: Present and Future
Observations of Mesoscale* Ocean
Circulation: Present and Future
Bo QiuDept of Oceanography University of Hawaii
Bo QiuDept of Oceanography University of Hawaii
A UH profiling float was being deployed from R/V Revelle in Kuroshio Extension, May ‘05
Schematic of Satellite Altimetry
* mesoscale = 10s~100s km
* mesoscale = 10s~100s km
Altimeter-derived rms sea surface height variability (cm)
Eddy “desert
”
Abundant mesoscale eddies
Altimeter-derived rms sea surface height variability (cm)
Schematic of NW Pacific Ocean Circulation
Semi-monthly Kuroshio Extension paths (1.7m SSH contours)
Stable yrs: 1993-94, 2002-04
Unstable yrs: 1996-2001, 2006-07
(a) Upstream KE path length (141-153°E)
(b) Eddy kinetic energy (141-153°E, 32-38°N)
Stable yrs: 1993-94, 2002-04
Unstable yrs: 1996-2001, 2006-07
Pacific Decadal Oscillations (Mantua et al. 1997)Pacific Decadal Oscillations (Mantua et al. 1997)
• Center of action of wind forcing is in the eastern half of the N Pacific basin
• Positive (negative) phase of PDO generates – (+) local SSH through Ekman divergence (convergence)
Yearly SSH anomaly field in the North Pacific Ocean
+
-
2004 stable
2005 unstable
20 floats 28 floats
UH-KESS profiling float measurements
1500db5 days
Kuroshio Extension System Study Observing Array/Timeline
Kuroshio Extension System Study Observing Array/Timeline
Distributions of semi-monthly profiling float T/S
data
(contours: SSH from satellite altimeters)
T(z) and PV(z) evolution in the KE recirculation gyre
mixed layer depth
subtropical mode water
KESS period
PV values on 25.4 σθ surface (~250m)
from mesoscale to submesoscale …from mesoscale to submesoscale …
What’s Next ?What’s Next ?
SSH snapshot from the NLOM model for 04/10/2006Right: from the original 1/32°-resolution output
Left: reduced to 1/2°-resolution (observable by current nadir-looking satellite altimeters)
SSH vs vorticity snapshot from the NLOM model for 04/10/2006
original 1/32°-resolution reduced 1/2°-resolution
original 1/32°-resolution
anticyclonic vorticity
cyclonic vorticity
PDF of modeled vorticity as a function of intensity
Ratio of anticycl./cyclonic vorticities
Recommended to NASA by the NRC Decadal Survey for Oceanographic and Hydrological Applications:
http://bprc.osu.edu/water
1. Point vs 200km-wide swath measurements
2. Repeat cycle: 10 days vs 3~5 days (at mid-high lat.)
“Surface Water and Ocean Topography (SWOT)” Mission
“Surface Water and Ocean Topography (SWOT)” Mission
Approximate Time and Space Scales of Oceanic Variability
Chelton (2001)
center of PDO
forcing
L
H
L
EKE level
SSHA along 34°N
SSH field
PDO index
145E 165E155E135E
Yearly-mean sea surface height field
Kuroshio Extension System Study (KESS) is designed to study KE’s transition/impact from a stable to unstable
state
KESS period
T(z), S(z) and PV(z) evolution in the KE recirculation gyre
mixed layer depth
subtropical mode water
Altimeter-derived rms sea surface height variability (cm)
Schematic of NW Pacific Ocean Circulation
Eddy “desert
”
Abundant eddies