Gustavo Jorge Goni* and Molly Baringer*Gustavo.Goni@noaa.gov

National Oceanic and Atmospheric AdministrationAtlantic Oceanographic and Meteorological Laboratory,

Miami, FL

NOAA Climate System ReviewSeptember, 2008

Goals and status of XBT network

Approximately 60% complete

Ocean observing system

57%

Total in situ networks 60 % complete May 2008

100%

40%

82%

43%72%48%21%

92%

“operational”sustained

70+ SOOP ships ocean obs900+ SOOP and VOS ships met bulletins

SHIP OF OPPORTUNITY Program (SOOP)

SOOP XBT deployments

High density (HD) mode: 1 XBT deployment every 25 km 4 transects per year

Frequently repeated (FR) mode: 6 XBT deployments per day (1 every 80 km) 18 transects per year

Low density (LD) mode: 4 XBT deployments per day (1 every 120 km) 12 transects per year Being replaced by Argo observations

XBT transects

Report on XBT network, OceanObs99: Neville Smith, D. Harrison, R. Bailey, O. Alves, T. Delcroix, K. Hanawa, R. Keeley, G. Meyers, R. Molinari, and D. Roemmich

Originally designed to investigate ENSO, SI variability

Science uses (Mostly HD transects)Eddy resolving, Identification of surface, subsurface currents, compute their mass transportsMeridional heat transportStrength of gyresValidation of modelsWater mass formationHeat budget

Operational uses:Data assimilation into modelsvalidation of models

SOOP FR XBT OceanObs99 recommendations

Adapted from: Neville Smith, D. Harrison, R. Bailey, O. Alves, T. Delcroix, K. Hanawa,

R. Keeley, G. Meyers, R. Molinari, D. Roemmich

The individual CLIVAR panels also provide recommendations, in addition to other regional, national and international recommendations.

25 recommended transects

The individual CLIVAR panels also provide recommendations, in addition to other regional, national and international recommendations.

SOOP HD XBT OceanObs99 recommendations

Adapted from: Neville Smith, D. Harrison, R. Bailey, O. Alves, T. Delcroix, K. Hanawa, R. Keeley, G. Meyers, R. Molinari, D. Roemmich

24 recommended transects

XBT and Argo observations2000-2007 (spatial distribution)

2000 2001 2002

2003 2004 2005

2006 2007

0

25000

50000

75000

100000

125000

# o

bs

erv

ati

on

s

Argo 7934 12210 20237 32420 48035 72203 95520 105000

XBTs (*) 12968 20592 19999 23303 26371 24098 21944 28000

2000 (inc)

2001 2002 2003 2004 2005 2006 2007

XBT and Argo observations2000-2007 (temporal distribution)

(*) Includes additional 4k XBTs per year that are not transmitted into the GTS

2006 ~22,000 deployments

XBT deployments

2007 ~28,000 deployments

40% Atlantic50% Pacific10% Indian

~20 transects done but not recommended

~11 transects recommended but not done

AX07 – long period signals

Courtesy of R. Molinari

AX08 – zonal currents in the TA

NECC

NEUCSEUC

SECC

NEC nSECcSEC

sSEC

Goni and Baringer, 2002

The FR-XBT Network and Ocean Data Assimilation Modeling

HRX line PX37/10/44 now has >16 years of quarterly sampling.

Time-varying heat budget for the region north of HRX line PX37/10/44. (Figs from Douglass, Roemmich and Stammer, 2008, submitted to DSR).

Heat transport from HRX data

Storage

A-S flux

From ECCO

Meridional heat advection

1990 1995 2000 2005

-0.4

0

0.4

0.8

1.2

35

ºS M

eri

dio

na

l He

at F

lux

(PW

)

ORCA 30ºS

1990 1995 2000 2005

-0.4

0

0.4

0.8

1.2

35

ºS M

eri

dio

na

l He

at F

lux

(PW

)

ECCO 35ºS

ORCA 30ºS

1990 1995 2000 2005

-0.4

0

0.4

0.8

1.2

35

ºS M

eri

dio

na

l He

at F

lux

(PW

)

ECCO 35ºS

ORCA 30ºS

AX18 35ºS

10 years

AX07 (zonal NA) AX18 (zonal SA)

The Oleander ProjectContinuous and simultaneous observations

URINOAA/NMFS, NOAA/AOMLSUNY

• 2 transects per week; 51 weeks per year

• Water sampling

• CPR since 1975

• XBTs since 1981

• TSG since 1992

• ADCP since 1993

• pCO2 since 2006

AX32

ISSUESGulf of Mexico and Caribbean Sea

1999-2005

ISSUES: HWRF and HYCOM

ISSUESGulf of Mexico and Caribbean Sea

A new challenge:XBT Fall rate equation

Recently published manuscriptsReport of workshop in OctoberWeb page by Tim Boyer (NODC)

Climatological isotherm depth estimates for the period 2000–2007 show positive differences between the XBT and Argo datasets that are statistically significant to 67%.

Is there a need for a re-evaluation of the XBT network and/or the observing system for upper ocean thermal studies ?

Some recommended transects are not being implemented (HD PX50).

Some recommended transect that are being implemented were not recommended (AX32-Oleander, HD AX98, LD/HD AX02).

There may be need to carry new transects (high latitude in NA).

There may be need to remove some transects (PX08).

Evaluate if some transects need to be sampled deeper than 800m.

Challenges

Challenges

Identification of all operational users (NCEP, US Navy’s MODAS, weather and climate model initialization...).

Identification of all scientific uses (data analysis, …)

Real-time transmission issues (Not all the data are transmitted in real-time into the GTS)

Can Argo floats alone provide adequate monitoring of the observing system for upper ocean heat storage ? If not, how can XBT and other platforms help ?

After 10 years of Argo, can we now evaluate if profiling float observation can reproduce XBT LD signals? May be it is too early to do this.

Evaluate if some transects need to be sampled with XCTD instead of XBTs.

There may not acceptable/sufficient scientific justification for some of the FRX transects.

Are current ocean models adequate to carry an evaluation of the system ? (OSSES)

BUFR and metadata.

XBT fall rate (work shop, manuscripts, data base).

Cost issues: ~$80 per XBT (~$35 when NOAA buys them) and $15 per transmission using Inmarsat (~$1.20 using Iridium, transition is currently is test phase).

Challenges

Drifter and Argo deployments

www.aoml.noaa.gov/phod/argo/opr

www.aoml.noaa.gov/phod/dac

Web pages

http://www.hrx.ucsd.edu/

http://www.aoml.noaa.gov/phod/goos/ldenxbt/index.php

www.aoml.noaa.gov/phod/hdenxbt/high_density_home.html