resolving surface currents and heat advection with the global drifter array
DESCRIPTION
Resolving Surface Currents and Heat Advection with the Global Drifter Array. Rick Lumpkin. Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration. NOAA Climate Observation Program 3 rd Annual System Review April 25-27, 2005. - PowerPoint PPT PresentationTRANSCRIPT
Rick LumpkinAtlantic Oceanographic and Meteorological Laboratory,
National Oceanic and Atmospheric AdministrationAtlantic Oceanographic and Meteorological Laboratory,
National Oceanic and Atmospheric Administration
NOAA Climate Observation Program3rd Annual System Review
April 25-27, 2005
Resolving Surface Currents and Heat Advection with the Global Drifter Array
Resolving Surface Currents and Heat Advection with the Global Drifter Array
1. What we can resolve1. What we can resolve
Time-mean currents75% of 1°1°bins!
Seasonal variations of SSTSeasonal variations of SST
Differences with satellite SST productsDifferences with satellite SST products
Differences with satellite SST productsDifferences with satellite SST products
Mean heat advectionMean heat advectionSST gradient (°C per degree)
Mean heat advection, upper 30m (W/m2)
Advection of SST anomaliesAdvection of SST anomalies
W/m
2
Anomalous heat advection, upper 30m (W/m2)
Surface current anomaliesSurface current anomalies
378 drogued
2. What we aren’t resolving2. What we aren’t resolving
(Drifters alone: any process happening in data gaps)
Eddy fluxes and anomalous advection of mean SSTEddy fluxes and anomalous advection of mean SST
Evaluating the drifter arrayEvaluating the drifter array
SURFACE CURRENTSAccuracy: 2 cm/sResolution: 600 kmNumber of measurements per month: 1
From Needler et al. 1999: Action plan for GOOS/GCOS and Sustained Observations for CLIVAR.
SST: GOOS evaluated by NOAA/NCDCSST: GOOS evaluated by NOAA/NCDC
Evaluating the drifter array
Before and after
3. How can we improve?3. How can we improve?
Predicting the arrayPredicting the array
Predicting the arrayPredicting the array
Include information from other measurements (altimetry, winds)Include information from other
measurements (altimetry, winds)
OSCARPilot project for a NOAA/NESDIS Operational Surface Current Processing and Data Center(F. Bonjean, J. Gunn, G. Lagerloef, E. Johnson)
Pilot project for a NOAA/NESDIS Operational Surface Current Processing and Data Center(F. Bonjean, J. Gunn, G. Lagerloef, E. Johnson)
170ºE-130ºW, 10ºS-10ºN
AvisoAVISO Altimetry productCollecte Localisation Satellites (CLS)Topex/Poseidon, Jason-1, ERS-1 and ERS-2
AVISO Altimetry productCollecte Localisation Satellites (CLS)Topex/Poseidon, Jason-1, ERS-1 and ERS-2
U(t)=U + A u’(t)
(methodology of Niiler et al., 2003)(methodology of Niiler et al., 2003)
Absolu
te speed (m
/s)
Drifters+wind, altimetryDrifters+wind, altimetry
altimeteraltimeter
large Rossby number flowlarge Rossby number flow
hgfvr
vr
2
(centrifugal) (Coriolis) (Pressure gradient)
L pg Corioliscentrifugal
H Cor pgcentrifugal
If we ignore centrifugal(assume geostrophy), we:
Underestimate Coriolis(underestimate v)
Overestimate Coriolis(overestimate v)
H
L
Drifters: calibrating satellite SSVDrifters: calibrating satellite SSV1
0.5
0
Drifters: in-situ calibration to reduce global bias in satellite SSV
Drifters: in-situ calibration to reduce global bias in satellite SSV
R. Lumpkin and G. Goni, NOAA/AOML
Summary: Global Drifter ArraySummary: Global Drifter Array• What we can resolve:
<U>, <SST>, <U>·<SST>, U(x,t) where coverage is sufficient mean eddy statistics
Drifter SST(x, t): cal/val of satellite products <U>· SST’
• What we can’t resolve:Anything in the “data holes”U(x,t) at sufficient resolution for time series
of eddy fluxes
•What we can do about this:Plan ahead: anticipate gapsSynthesize drifters, winds and altimetry for
operational surface currentsDrifter U(x,t) cal/val of satellite products
fin
Terms in NINO3 region