NASA Scatterometer Experiment

Graf, James E.; Sasaki, Chester; Winn, C. B.; Liu, W.T; Tsai, Wu-Yang; Freilich, Michael H.; Long, D.G.

doi:10.1016/s0094-5765(97)00180-x

Cited by 42 publications

(25 citation statements)

References 3 publications

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“…The zonally integrated Ekman transport between the Bahamas and the coast of West Africa is computed from the zonal component of the wind stress, which is inferred from space-borne scatterometry (Graf et al, 1998) on a daily basis.…”

Section: The Rapid/mocha Arraymentioning

confidence: 99%

Observed and simulated estimates of the meridional overturning circulation at 26.5° N in the Atlantic

et al. 2009

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Abstract.Daily timeseries of the meridional overturning circulation (MOC) estimated from the UK/US RAPID/MOCHA array at 26.5 • N in the Atlantic are used to evaluate the MOC as simulated in two global circulation models: (I) an 8-member ensemble of the coupled climate model ECHAM5/MPI-OM, and (II) the ECCO-GODAE state estimate. In ECHAM5/MPI-OM, we find that the observed and simulated MOC have a similar variability and time-mean within the 99% confidence interval. In ECCO-GODAE, we find that the observed and simulated MOC show a significant correlation within the 99% confidence interval. To investigate the contribution of the different transport components, the MOC is decomposed into Florida Current, Ekman and mid-ocean transports. In both models, the midocean transport is closely approximated by the residual of the MOC minus Florida Current and Ekman transports. As the models conserve volume by definition, future comparisons of the RAPID/MOCHA mid-ocean transport should be done against the residual transport in the models. The similarity in the variance and the correlation between the RAPID/MOCHA, and respectively ECHAM5/MPI-OM and ECCO-GODAE MOC estimates at 26.5 • N is encouraging in the context of estimating (natural) variability in climate simulations and its use in climate change signal-to-noise detection analyses. Enhanced confidence in simulated hydrographic and transport variability will require longer observational time series.

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Section: The Rapid/mocha Arraymentioning

confidence: 99%

Observed and simulated estimates of the meridional overturning circulation at 26.5° N in the Atlantic

et al. 2009

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“…Surface wind speed estimates (combined with wind directions from ECMWF analysis) are available on a 1˚x1˚ longitude-latitude grid for the1988-2000 period from the Special Sensor Microwave Imager (Atlas et al 1996), and this record is supplemented by the QuikSCAT scatterometer winds (Graf et al 1998) for the period mid-1999 to 2006.…”

Section: Surface Windsmentioning

confidence: 99%

Origin of the Springtime Westerly Bias in Equatorial Atlantic Surface Winds in the Community Atmosphere Model Version 3 (CAM3) Simulation

2008

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.The study makes the case that westerly bias in the surface winds of the NCAR atmospheric and coupled models (CAM3 and CCSM3, respectively) over the equatorial Atlantic in boreal spring has its origin in the rainfall (diabatic heating) bias over the tropical South American continent. The case is made by examination of the spatio-temporal evolution of regional precipitation and wind biases, and by dynamical diagnoses of the westerly wind bias from experiments with a steady, linearized dynamical core of an atmospheric general circulation model. Diagnostic modeling indicates that underestimation of rainfall over the eastern Amazon region can lead to the westerly bias in equatorial Atlantic surface winds.The study suggests that efforts to reduce coupled model biases, especially seasonal ones, must target continental biases, even in the deep Tropics where ocean-atmosphere interaction generally rules.

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“…Our SST observation dataset has the same combination of SST datasets that are used for the CAM3 AMIP run (Rayner et al 2003;Reynolds et al 2002). Observed surface winds are available also in a 1°ϫ 1°grid from the Special Sensor Microwave Imager for the 13-yr period of 1988-2000(Atlas et al 1996 and are patched with the National Aeronautics and Space Administration (NASA) Quick Scatterometer (QuikSCAT) winds (Graf et al 1998), which are available from mid-1999 to 2005. These nominally 10-m winds have an uncertainty of Ϯ 2 ms Ϫ1 in our sector of interest.…”

Section: Model and Datamentioning

confidence: 99%

Seasonal Climate of the Tropical Atlantic Sector in the NCAR Community Climate System Model 3: Error Structure and Probable Causes of Errors

et al. 2007

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The Community Climate System Model version 3 (CCSM3) has a dipolelike pattern with a cold bias in the northern Tropics and a warm bias in the southeastern Tropics, which is reminiscent of the observed pattern of climate variability in boreal spring. Along the equator, in contrast, in boreal spring CCSM3 exhibits striking westerly winds with easterly winds in the upper troposphere, in turn reminiscent of the observed pattern of climate variability in boreal summer. The westerly winds cause a deepening of the eastern thermocline that keeps the east warm despite enhanced coastal upwelling. Thus, the bias in the seasonal cycle of the coupled model appears to project at least partially onto the spatial patterns of natural climate variability in this sector.Information about the origin of the bias in CCSM3 is deduced from a comparison of CCSM3 with a simulation using specified historical SST to force the Community Atmospheric Model version 3 (CAM3). The patterns of bias in CAM3 resemble those apparent in CCSM3, including the appearance of substantially intensified subtropical bands of sea level pressure (SLP), indicating that the problem may be traced to difficulties in the atmospheric component model. Positive SLP bias also appears in the western tropical region, which may be related to deficient Amazonian precipitation. The positive SLP bias seems to be the cause of the anomalous westerly trade winds in boreal spring, and those in turn appear to be responsible for the anomalous deepening of the thermocline in the southeastern Tropics.

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NASA Scatterometer Experiment

Cited by 42 publications

References 3 publications

Observed and simulated estimates of the meridional overturning circulation at 26.5° N in the Atlantic

Observed and simulated estimates of the meridional overturning circulation at 26.5° N in the Atlantic

Origin of the Springtime Westerly Bias in Equatorial Atlantic Surface Winds in the Community Atmosphere Model Version 3 (CAM3) Simulation

Seasonal Climate of the Tropical Atlantic Sector in the NCAR Community Climate System Model 3: Error Structure and Probable Causes of Errors

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