Bulk models of solar radiation at sea

Dobson, Fred W.; Smith, Stuart D.

doi:10.1002/qj.49711447909

Cited by 131 publications

(37 citation statements)

References 12 publications

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“…Surface downward solar radiation is strongly affected by cloud cover, and it is often modeled using cloudiness data (e.g., Dobson and Smith 1988). The NCEP-NCAR reanalysis downward solar radiation anomaly is highly correlated with the reanalysis total cloud cover anomaly (Fig.…”

Section: Surface Downward Solar Radiationmentioning

confidence: 99%

Simulation of Global Land Surface Conditions from 1948 to 2004. Part I: Forcing Data and Evaluations

Qian

Dai

Trenberth

et al. 2006

Journal of Hydrometeorology

427

506

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Because of a lack of observations, historical simulations of land surface conditions using land surface models are needed for studying variability and changes in the continental water cycle and for providing initial conditions for seasonal climate predictions. Atmospheric forcing datasets are also needed for land surface model development. The quality of atmospheric forcing data greatly affects the ability of land surface models to realistically simulate land surface conditions. Here a carefully constructed global forcing dataset for 1948-2004 with 3-hourly and T62 (ϳ1.875°) resolution is described, and historical simulations using the latest version of the Community Land Model version 3.0 (CLM3) are evaluated using available observations of streamflow, continental freshwater discharge, surface runoff, and soil moisture. The forcing dataset was derived by combining observation-based analyses of monthly precipitation and surface air temperature with intramonthly variations from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis, which is shown to have spurious trends and biases in surface temperature and precipitation. Surface downward solar radiation from the reanalysis was first adjusted for variations and trends using monthly station records of cloud cover anomaly and then for mean biases using satellite observations during recent decades. Surface specific humidity from the reanalysis was adjusted using the adjusted surface air temperature and reanalysis relative humidity. Surface wind speed and air pressure were interpolated directly from the 6-hourly reanalysis data. Sensitivity experiments show that the precipitation adjustment (to the reanalysis data) leads to the largest improvement, while the temperature and radiation adjustments have only small effects.When forced by this dataset, the CLM3 reproduces many aspects of the long-term mean, annual cycle, interannual and decadal variations, and trends of streamflow for many large rivers (e.g., the Orinoco, Changjiang, Mississippi, etc.), although substantial biases exist. The simulated long-term-mean freshwater discharge into the global and individual oceans is comparable to 921 river-based observational estimates. Observed soil moisture variations over Illinois and parts of Eurasia are generally simulated well, with the dominant influence coming from precipitation. The results suggest that the CLM3 simulations are useful for climate change analysis. It is also shown that unrealistically low intensity and high frequency of precipitation, as in most model-simulated precipitation or observed time-averaged fields, result in too much evaporation and too little runoff, which leads to lower than observed river flows. This problem can be reduced by adjusting the precipitation rates using observed-precipitation frequency maps.

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Section: Surface Downward Solar Radiationmentioning

confidence: 99%

Simulation of Global Land Surface Conditions from 1948 to 2004. Part I: Forcing Data and Evaluations

Qian

Dai

Trenberth

et al. 2006

Journal of Hydrometeorology

427

506

View full text Add to dashboard Cite

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“…Corrections have been proposed for the different measurement methods (Kent and Kaplan, 2006), however, there is still uncertainty in both the magnitude and sign of the bias. SST observations are therefore left unadjusted and the bias uncertainty is estimated based on the results of (Dobson and Smith, 1988) peak at 1 octa rather than for clear sky. ) and the present study (dotted: 0.966 * q air ).…”

Section: Sea Surface Temperaturementioning

confidence: 99%

Air–Sea fluxes from ICOADS: the construction of a new gridded dataset with uncertainty estimates

Berry

Kent

2011

Intl Journal of Climatology

102

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ABSTRACT:The methods used to calculate a new in situ global dataset of air-sea exchanges, called the NOCS Flux Dataset v2.0, are described. The fluxes have been derived from in situ weather reports from Voluntary Observing Ships (VOS) covering the period 1973-2006. The reports have been adjusted for known biases and residual uncertainties estimated. The dataset is constructed using Optimal Interpolation (OI) using new estimates of random uncertainty in the observations. Daily fields have been calculated on a 1°latitude by 1°longitude grid, each grid box and time step have an associated uncertainty estimate. Monthly fields have been calculated from simple averages of the daily fields and monthly uncertainty estimates from the daily uncertainties, using estimates of the autocorrelation between the daily uncertainty estimates. The uncertainties due to the choice of flux parameterisation have not been accounted for. Bias adjustments applied to the data are shown to reduce trends in the data and to improve the consistency of estimates of air temperature, sea surface temperature (SST) and specific humidity. The bias adjustments also improve the agreement of NOCS v2.0 with independent data from research moorings. Cross-validation of the dataset suggests that the uncertainty estimates are realistic, but that the uncertainties are probably underestimated in high variability regions and overestimated in regions with lower variability. Copyright BackgroundReliable estimates of air-sea fluxes of heat, freshwater and momentum are needed to improve our understanding of the coupled ocean-atmosphere system. The main physical interactions at the sea surface are the turbulent heat, moisture and momentum fluxes between the ocean and the atmosphere, the radiative warming of the ocean surface by solar radiation and the net cooling of the ocean surface by thermal radiation. Direct measurements of the turbulent fluxes are typically only made on air-sea interaction research cruises and dedicated moored buoys and platforms. This limits the availability of direct flux measurements in space and time and their usefulness for global studies. As a result, global marine flux datasets are typically constructed using bulk estimates of the mean meteorological parameters and bulk parameterisations (or bulk formulae) developed using coincident measurements of the direct and radiative fluxes and mean meteorological variables from research cruises.The meteorological parameters required by the bulk formulae are: air temperature and humidity; sea surface temperature (SST); wind speed; sea level pressure; and cloud cover. These parameters are available from different sources including ship and buoy observations,

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“…Despite its significance, it remains a very poorly recorded quantity; solar radiation over the ocean is usually estimated either from empirical parameterizations using the commonly recorded cloudiness and the noon solar elevation [e.g., Budyko , 1974; Reed , 1977], or from radiative transfer models using satellite records [e.g., Bishop et al , 1997; Gupta et al , 1999]. Because of the duration and the simplicity of the former they are still widely used in oceanography and climate modeling, although it is well known that such parameterizations often introduce systematic errors [e.g., Dobson and Smith , 1988].…”

Section: Introductionmentioning

confidence: 99%

Role of aerosols on the Mediterranean solar radiation

Tragou

Lascaratos

2003

J. Geophys. Res.

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[1] The shortwave radiation constitutes a major driving force for the oceanic thermohaline circulation and must be accurately parameterized. An extensive comparison between the monthly mean solar radiation measured at numerous meteorological stations along the Mediterranean coast and the estimated solar radiation from a widely used bulk formula leads to two important conclusions: first, there is systematic overestimation of the shortwave radiation from the bulk formula at the station sites of about 25 W m À2(averaged over a 30 year period), and second, there is significant interannual variability in the observed solar radiation that cannot be explained either by the variability in the available data for the cloudiness or by the absorption due to water vapor content in the atmospheric column. As the overestimation occurs during summer cloud-free months, we assume that cloud attenuation is adequately parameterized and the discrepancy between the observations and the estimates comes from the formula for clear-sky insolation. A correction to the clear-sky insolation formula is attempted on the basis of recent satellite data on aerosol optical thickness index. Results from our analysis indicate that aerosols may provide an explanation for both the observed weaker shortwave radiation and its interannual variations. This implies that a different parameterization scheme must be sought for the aerosol attenuation in the shortwave radiation formula. INDEX TERMS: 4504

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Bulk models of solar radiation at sea

Cited by 131 publications

References 12 publications

Simulation of Global Land Surface Conditions from 1948 to 2004. Part I: Forcing Data and Evaluations

Simulation of Global Land Surface Conditions from 1948 to 2004. Part I: Forcing Data and Evaluations

Air–Sea fluxes from ICOADS: the construction of a new gridded dataset with uncertainty estimates

Role of aerosols on the Mediterranean solar radiation

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