Quantifying Uncertainties in NCEP Reanalyses Using High-Quality Research Vessel Observations

Smith, Shawn R.; Legler, David M.; Verzone, Kathleen V.

doi:10.1175/1520-0442(2001)014<4062:quinru>2.0.co;2

Cited by 191 publications

(162 citation statements)

References 14 publications

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“…Kanamitsu et al (2002) stated that the NCEPR2 was a follow-on project to the initial NCEP-National Center for Atmospheric Research (NCEPR1) reanalysis (Kalnay et al, 1996) that fixes the human processing errors discovered in the NCEPR1. This comment, along with previous studies showing large biases in NCEPR1 heat fluxes (Bony et al, 1997;Smith et al, 2001), results in the exclusion of the NCEPR1. In addition, we have not examined the plethora of recently released reanalysis products.…”

Section: Reanalysissupporting

confidence: 61%

“…Although they can take advantage of the complete spatial and temporal coverage of the reanalysis products, they are then subject to the internal biases of these products, as well as large random errors in the SO. For example, NCEPR1 has been shown to underestimate the wind speed in the Tropics (Putman et al, 2000) and Smith et al (2001) revealed a cold bias in NCEPR1 compared to research ship observations. As noted above, the Gibbs phenomenon is prominent in the NCEPR1 and this propagates into the GSSTF2 and the early versions of the OAFLUX product.…”

Section: Hybridmentioning

confidence: 97%

“…Both operational and research users continue to seek the 'best' estimate of air-sea fluxes for their applications. At present, many users are working with older, outdated flux products that have been shown to have severe limitations (Bony et al, 1997;Putman et al, 2000;Smith et al, 2001;Chou et al, 2003;Kubota et al, 2003). In fact, several of the flux products considered in this manuscript have been updated since this work was completed; however, the community will continue to use the nine analysed products so that an assessment of their characteristics and limitations is valuable.…”

Section: Introductionmentioning

confidence: 99%

“…On a monthly scale, the reanalysis products (Kalnay et al, 1996;Kanamitsu et al, 2002;Uppala et al, 2005;Onogi et al, 2007) have the advantage of longer time series than satellite-derived fields and the addition of upper-air fields for 3D analysis. However, early reanalysis products (Kalnay et al, 1996) are noted to have a poor handling of the wind field in equatorial regions (Putman et al, 2000), as well as large biases in heat fluxes (Bony et al, 1997;Smith et al, 2001). The flux parameterisations used in these reanalyses are not consistent with state-of-the-art flux models (Brunke et al, 2002;Curry et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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A comparison of nine monthly air–sea flux products

Smith

Hughes

Bourassa

2010

Intl Journal of Climatology

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A comparison is conducted between nine monthly turbulent air-sea flux products. The analysis includes in situ-based (Florida State University fluxes, FSU3 and National Oceanography Centre, NOC), satellite-based (Hamburg Ocean-Atmosphere Parameters from Satellite data, HOAPS2 and the French Research Institute for Exploitation of the Sea, IFREMER), hybrid (Goddard Satellite-based Surface Turbulent Fluxes, GSSTF2 and objectively analysed fluxes, OAFLUX), and reanalysis (National Centers for Environmental Prediction, NCEPR2, Japanese 25-year reanalysis, JRA, and European Centre for Medium Range Weather Forecasts reanalysis, ERA-40) products. Objectives include documenting the varying analysis methodologies and quantifying the differences and similarities between the nine products. Recommendations are made for developers of future flux products and to guide users to select products most suitable for their application.The comparison examines turbulent fluxes of heat and momentum along with the forcing variables (air temperature, wind speed, humidity, and ocean skin temperature) that are necessary to estimate turbulent fluxes. The wide range of turbulent flux parameterisations, sampling patterns, and averaging techniques within the products are described, including some of the difficulties product differences pose when trying to compare or apply the individual products. Global comparisons of monthly means tend to reveal similar spatial patterns in latent heat flux (LHF) and sensible heat flux (SHF) for the nine products; however, the magnitudes and patterns of variability (expressed as maps of standard deviations) are widely different. Basin scale and regional analysis further reveals large differences in the products (in some cases the interquartile ranges (IQRs) do not overlap for different products), but also reveals potential sources of the differences. For example, some of the variations in LHF can be explained by large differences in the distribution of specific humidity between the products. As a final analysis, we examine how each product represents the variations in turbulent fluxes in the equatorial Pacific (EP) Ocean. This analysis provides an example of how the choice of a flux product, and understanding the strengths and weaknesses of that product, can alter research findings.

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Section: Reanalysissupporting

confidence: 61%

Section: Hybridmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A comparison of nine monthly air–sea flux products

Smith

Hughes

Bourassa

2010

Intl Journal of Climatology

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“…When compared to buoy data, NCEP overestimates low winds but it underestimates the speed for larger wind speeds. Similar result was obtained in the comparison of NCEP and a surface meteorological data set from research vessels by Smith et al [2001]. Their analysis reveals that biases in model winds result from pressure biases that make NCEP underestimate the amplitude and/or position of both high and low pressures.…”

Section: Ncep Reanalysismentioning

confidence: 99%

Wind forcing of the coastal circulation off north and northwest Iberia: Comparison of atmospheric models

Otero-Tranchero

Ruiz-Villarreal

2008

J. Geophys. Res.

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[1] Comparisons between observed winds and winds from reanalysis (National Centers for Environmental Prediction (NCEP) Reanalysis 1 and 2) and forecast meteorological models (High-Resolution Limited Area Model (HIRLAM)-Agencia Estatal de Meteorologia 0.2°and Atmospheric Research Mesoscale Model version 5-MeteoGalicia with 30 km and 10 km resolution) have been performed for the coastal region around northwest and north Iberia during a typical autumn downwelling period (SeptemberDecember 2002). Observations at buoys and coastal stations and QuikSCAT-derived winds were employed. The analyzed period was dominated by southerly and southwesterly winds associated to the passage of low-pressure systems. Our results show that the westward component is higher on the north coast than on the west coast and that winds are intensified at the western north coast. In this situation, the performance is similar in all model products in general terms, but only HIRLAM represents the reduction of winds in the Cantabrian Sea and NCEP and MM5 overestimate the magnitude of southsouthwest winds. Spatial differences in winds are also obtained for upwelling favorable events, associated either with a high-pressure system north from Iberia at the beginning of the autumn transition (northeasterly winds) or with conditions after the passage of a lowpressure system (northwesterly winds). The existence of sea surface temperature (SST) gradients in the coastal region implies that higher-resolution boundary SST products for meteorological models are necessary. Finally, the effect of these wind products on the coastal circulation was assessed with a 3-D numerical simulation. Differences in the expansion/confinement of river plumes and the surface speed of the slope current are induced by differences in wind patterns over the shelf and slope area among atmospheric models.Citation: Otero, P., and M. Ruiz-Villarreal (2008), Wind forcing of the coastal circulation off north and northwest Iberia: Comparison of atmospheric models,

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What causes the location of the air‐sea turbulent heat flux maximum over the Labrador Sea?

Moore

Pickart

Renfrew

et al. 2014

Geophysical Research Letters

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The Labrador Sea is a region of climatic importance as a result of the occurrence of oceanic wintertime convection, a process that is integral to the Atlantic Meridional Overturning Circulation. This process requires large air-sea heat fluxes that result in a loss of surface buoyancy, triggering convective overturning of the water column. The Labrador Sea wintertime turbulent heat flux maximum is situated downstream of the ice edge, a location previously thought to be causal. Here we show that there is considerable similarity in the characteristics of the regional mean atmospheric circulation and high heat flux events over the Labrador Sea during early winter, when the ice is situated to the north, and midwinter, when it is near the region of maximum heat loss. This suggests that other factors, including the topography of the nearby upstream and downstream landmasses, contribute to the location of the heat flux maximum.

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Quantifying Uncertainties in NCEP Reanalyses Using High-Quality Research Vessel Observations

Cited by 191 publications

References 14 publications

A comparison of nine monthly air–sea flux products

A comparison of nine monthly air–sea flux products

Wind forcing of the coastal circulation off north and northwest Iberia: Comparison of atmospheric models

What causes the location of the air‐sea turbulent heat flux maximum over the Labrador Sea?

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