# Presentation: 400197

## Don Chambers
Center for Space Research
The University of Texas at Austin

Victor Zlotnicki
Jet Propulsion laboratory
California Institute of Technology

OST Science Team Meeting
St. Petersburg, FL
 November 4-6 2004

- Center for Space Research
- The University of Texas at Austin
**Victor Zlotnicki**
- Jet Propulsion laboratory
- California Institute of Technology
**OST Science Team Meeting**
**St. Petersburg, FL**
** ****November 4-6 2004**

**GRACE Products for Oceanography**

## Dynamic Ocean Topography (DOT) = Mean Sea Surface (MSS) - geoid
MSS is MSS used for Jason GDRs (GSFCMSS00)
Geoid is based on new average from GRACE SDS at CSR, GGMO2C
363-days of satellite information combined with surface gravity
Complete to degree/order 200
Can be extended to degree/order 360 with EGM96 with no obvious discontinuity

- MSS is MSS used for Jason GDRs (GSFCMSS00)
- Geoid is based on new average from GRACE SDS at CSR, **GGMO2C**
- 363-days of satellite information combined with surface gravity
- Complete to degree/order 200
- Can be extended to degree/order 360 with EGM96 with no obvious discontinuity

## DOT 0

- Dynamic Ocean Topography (DOT) = GSFCMSS00 - GGM02C geoid; GGM02C extended to degree 360 with EGM96

**DOT 0**

**Slide 1**

## DOT 1

- Map DOT to 0.5° grid using a Gaussian spatial smoother; filter suppresses signals with wavelengths < 888 km.

**DOT 1**

**Slide 2**

## DOT 0 - DOT 1

**DOT 0 - DOT 1**

- Residual signal in full resolution DOT (**DOT 0**) unresolved by smoothing (**DOT 1**); evident features related to circulation (e.g., arrows), but also signals related to geoid (e.g., vertical stripes, seamounts, trenches).

**Slide 3**

## Smooth residual signal (DOT 0 - DOT 1) to keep features related to circulation, but not geoid; because of vertical striping, use spherical harmonic (SH) expansion to degree 360 and weighted coefficients with a function in SH space equivalent to a spatial Gaussian with a half-width of 222 km [Wahr et al., JGR, 1998].

- Smooth residual signal (**DOT 0 - DOT 1**) to keep features related to circulation, but not geoid; because of vertical striping, use spherical harmonic (SH) expansion to degree 360 and weighted coefficients with a function in SH space equivalent to a spatial Gaussian with a half-width of 222 km [Wahr et al., *JGR*, 1998].

**Slide 4**

## DOT 2

**DOT 2**

- Add smoothed residual signal to **DOT 1****.**

**Slide 5**

## DOT 0 - DOT 2

**DOT 0 - DOT 2**

- Still some residual signal which appears to be related to ocean circulation,  but not as much as before.

**Slide 6**

## Smooth residual signal (DOT 0 - DOT 2) as before but with a SH-equivalent half-width of 200 km. We find that at any smaller radius, the vertical stripes begin to appear.

- Smooth residual signal (**DOT 0 - DOT 2**) as before but with a SH-equivalent half-width of 200 km. We find that at any smaller radius, the vertical stripes begin to appear.

**Slide 7**

## Final DOT

**Final DOT**

- Add smoothed residual signal to **DOT 2****.**

**Slide 8**

## Zonal geostrophic currents implied by Final DOT. Eastward is positive.

- Zonal geostrophic currents implied by **Final DOT****. **Eastward is positive.

**Slide 9**

## Meridional geostrophic currents implied by Final DOT. Northward is positive.

- Meridional geostrophic currents implied by **Final DOT****. **Northward is positive.

**Slide 10**

## DOT and circulation grids (at 0.5° resolution) will soon be available from PODAAC
Other items to follow
Along-track DOT from Jason-1 SLA products
Monthly climatology DOT
Sub-surface circulation maps from combination with World Ocean Atlas 2001
Funding for project from NASA 
Earth Science Research, Education and Applications Solutions Network (Earth Science REASoN ).

- Other items to follow
- Along-track DOT from Jason-1 SLA products
- Monthly climatology DOT
- Sub-surface circulation maps from combination with World Ocean Atlas 2001
- Funding for project from NASA
- Earth Science *Research, Education and Applications Solutions Network *(Earth Science *REASoN *).