Rapid Climate Change (RAPID)

programme

Meric SrokoszSouthampton Oceanography Centre

Natural Environment Research Council (NERC)

mas@soc.soton.ac.uk

http://rapid.nerc.ac.uk

Bermuda Rise marine sediment & Greenland ice coreBermuda Rise marine sediment & Greenland ice core

From Adkins et al. (1997) - high deposition rate 20-100cm/kyr

Matching the time scales of various palaeo proxies is a problemRecords need high temporal resolution and dating accuracy to detect rapid climate change events

Impact of THC collapse in numerical modelsImpact of THC collapse in numerical models

(courtesy Michael Vellinga, Hadley Centre)

Temperature change in deg. C if collapse occurs in 2050, mean for first decade relative to pre-industrial (HadCM3)

Model predictions of THC changes due to global warmingModel predictions of THC changes due to global warming

Wide range of predictions from different models

Uncertainty within models also not well understood

RAPID - Overall objectiveRAPID - Overall objective

RAPID aims to investigate and understand the causes of

rapid climate change, with a main (but not exclusive)

focus on the role of the Atlantic Ocean’s Thermohaline

Circulation (THC)

paleo data

modelling

observations

Observational focus on North Atlantic

NERC £20M2001-2008

RAPID fundingRAPID funding

4 Announcements of Opportunity (AO), plus SBRI– Monitoring the Atlantic Meridional Overturning Circulation ~£5M

Specific AO to develop pre-operational “early-warning” system (3 projects)

Working with NSF and NOAA

– Joint AO with NWO (Netherlands) & RCN (Norway)

To build on ongoing activities in all three countries, and benefit from a cross-national effort (5 projects)

– 1st & 2nd “Science” AO (28 projects)

2nd AO focus on synthesis / data assimilation of observations

– Small Business Research Initiative (4 projects)

Data management ~£1M through NERC data centres

Monitoring the Atlantic MOCMonitoring the Atlantic MOC

Cannot measure THC per se but can measure the meridional overturning circulation (MOC) and the associated heat transport

Collaboration between NERC - NSF - NOAA– 26.5˚N array Bryden / Cunningham (SOC), Marotzke (MPI,

Germany), Johns (Miami) & Baringer (AOML) meridional heat transport, Florida Straits current measurements

– Deep Western Boundary Current (DWBC) observations - Hughes (POL) Grand Banks and Halifax arrays & Toole (WHOI) WHOI-Bermuda line

– Watson (UEA) autosamplers for 129I

– Rossby (URI) Oleander line NY-Bermuda

Monitoring the MOC - 26.5˚N & Deep Western Boundary CurrentMonitoring the MOC - 26.5˚N & Deep Western Boundary Current

(arrays deployed in 2004)

Monitoring locations

DWBCDWBC

POL RapidLander BPR

Arrays deployed Apriland August 2004

WAVE = Western Atlantic Variability Experiment

Boundary signals in altimetry and modelsBoundary signals in altimetry and models

Correlation of high pass filtered altimetry everywhere with that averaged in the northern NE Atlantic (marked in black dots). Places where correlation is not significant at the 95% level are left white (Hughes, POL).

Williams & Roussenov (Liverpool) are trying to model these boundary signal at the surface and at depth.

26.5˚N monitoring method26.5˚N monitoring method

Gulf Stream transport - Florida Straits cable

Ekman transport - using wind climatology

Interior geostrophic flow - mooring array

Heat transport - XBT sections, CTD sections

Atlantic MOC array at 26.5˚N (deployed Feb/Mar 2004)Atlantic MOC array at 26.5˚N (deployed Feb/Mar 2004)

Western boundary3 Miami moorings, rest of array SOC moorings

Moored profiler D277/8Moored profiler D277/8

U. Miami & SOC mooringteams

Complete array as deployed February-March 2004Complete array as deployed February-March 2004

ADCP W

EBH5

EB1EB2

EB3

EBH1

EBH2

EBH3

EBH4

MAR2 MAR1 MAR3MAR4WB4

WB2WBH1

WBH2

WB1

BJ A

BJ BBJ E

ADCP E

Currently being recovered and re-deployed (Darwin and Knorr cruises)

D279D279

SOC cruise to calibrate 26.5N array

Monitoring the Atlantic MOC at 26.5˚NMonitoring the Atlantic MOC at 26.5˚N

Estimate

MOC

Placingof densityprofiles

(Hirschi et al.GRL 2003)

OCCAM

FLAME

Calibrating sediment cores with modern observationsCalibrating sediment cores with modern observations

Geostrophic currents from D230x = current meter

Palaeo data from Eirik Ridge sediments on past changes in DWBC

Measure DWBC

---- CTD / LADCP sections

Bacon (SOC)McCave (Cambridge)

Surface fluxes associated with weakening MOCSurface fluxes associated with weakening MOC

HadCM3 MOC Weakening Composite

SOC Flux Dataset NAO Composite

Anomalous Heat Flux for 5 year period prior to weakening event

Josey et al., 2001, GRL, 28(24), 4543-4546

Josey (SOC)

New model for open ocean deep convectionNew model for open ocean deep convection

Munk gyre problem. Upper ocean currents caused by the wind stress, and intensified at the western boundary, due to frictional effects. Animation shows the flow adapting finite element grid. (2-D:v-velocity comp.)

Pain (Imperial College)

Where next?Where next?

MOC observing system seen as key part of N. Atlantic

observations by CLIVAR for decadal climate prediction

– Recommendation of CLIVAR workshop on Atlantic Predictability 2004

MOC observing system is funded for 4 years (to 2008)

– RAPID will provide proof of concept but to detect significant MOC

change requires ….. (longer)

Potential for further funding in UK, but require:

– Successful peer reviewed proposal (submitted by early 2006?)

– Continued international collaboration (NOAA, NSF)

– Links to other international work in N. Atlantic (e.g. MOVE array at

16˚N, ASOF arrays in northern N. Atlantic)