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C. Potter, S. Klooster, P. Tan, M. Steinbach, V. Kumar, and V. Genovese

radiative transfer algorithms ( Knyazikhin et al. 1998 ), which are designed to generate improved spatially varying FPAR products as inputs to carbon flux calculations. These radiative transfer algorithms, developed for the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA Terra platform, account for attenuation of direct and diffuse incident radiation by solving a three-dimensional formulation of the radiative transfer process in vegetation canopies. Monthly gridded composite data

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C. Potter, S. Klooster, P. Tan, M. Steinbach, V. Kumar, and V. Genovese

., 1993 ; Potter et al., 1999 ) used a normalized difference vegetation index (NDVI) to estimate FPAR, the current model version instead relies upon canopy radiative transfer algorithms ( Knyazikhin et al., 1998 ), which are designed to generate improved spatially varying FPAR products as inputs to carbon flux calculations. These radiative transfer algorithms, developed for the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA Terra platform, account for attenuation of direct

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Christopher Potter, Steven Klooster, David Bubenheim, Hanwant B. Singh, and Ranga Myneni

for orbital drifts and switches between satellites (e.g., NOAA-9 to NOAA-11 ). The input of live foliar density values to our model [ Equation (1) ] is made in terms of LAI derived from modified Moderate Resolution Imaging Spectroradiometer (MODIS) radiative transfer algorithms ( Buermann et al., 2001 ), using the Global Invenory Monitoring and Modelling System (GIMMS) AVHRR data from 1982 to 1999. The global MODIS algorithm products we use include improved calibration for intra- and

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Walter N. Meier, James A. Maslanik, Charles W. Fowler, and Jeffrey R. Key

1. Introduction The polar regions play an important role in the global climate due in part to the effects of sea ice and cloud cover on albedo and energy transfer. Turbulent heat fluxes during winter and solar energy absorbed by the ocean in summer are controlled largely by the open-water area and lead fraction in the ice pack, while radiative fluxes are regulated primarily by solar insolation, cloud properties, and surface albedo/emissivity. Efforts to gain a better understanding of these

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Ayan H. Chaudhuri and Rui M. Ponte

Operational Global Forecast System (GFS) model coupled with the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model, version 4 (MOM4) and sea ice model. Atmospheric observations are assimilated via the three-dimensional variational data assimilation (3DVAR) Gridpoint Statistical Interpolation (GSI) system. The CFSR utilizes the Rapid Radiative Transfer Model (RRTM) ( Mlawer et al. 1997 ). A more detailed description is provided in Saha et al. (2010) . NASA’s MERRA reanalysis is a ½° × ⅔

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Mohammad H. Mokhtari, Ibrahim Busu, Hossein Mokhtari, Gholamreza Zahedi, Leila Sheikhattar, and Mohammad A. Movahed

atmospheric conditions and land surface attributes is a requisite for determining surface albedo by satellite data ( Liang et al. 2002 ). Since satellite sensors measure narrow bands at the top of the atmosphere, reflectance data are converted to surface broadband albedo by extensive radiative transfer simulation and then by linking simulated top-of-atmosphere reflectance with surface broadband albedo using a nonparametric regression algorithm ( Liang et al. 2002 ) or following the method presented by the

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M. P. Maneta and N. L. Silverman

observed (black line). The simulation of net radiation ( Figure 5b ) also showed satisfactory statistics with an R 2 of 0.99 and an RMSE of 54.15 W m −2 . The daytime peaks were remarkably well simulated but the nighttime lows were consistently underestimated. This was likely due to enhanced heat transfers to the soil surface from the aerodynamic resistance formulations during the stable nighttime periods, where radiative outgoing fluxes should dominate the energy balance. Ground heat ( Figure 5c

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Christopher Potter, Shyam Boriah, Michael Steinbach, Vipin Kumar, and Steven Klooster

1 km). In this study, we have used MODIS collection 4, which represents the latest available version of MODIS products and contains the entire time series of data from February 2000 to 2005. At 4-km spatial resolution, the land area constitutes about 42.5 million pixels, of which 32 million are vegetated. The main MODIS fraction absorbed of photosynthetically active radiation (FPAR) algorithm performs retrievals from daily surface reflectance data based on radiative transfer algorithms

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C. L. Tague and L. E. Band

absorption by the snowpack is computed based on a Beer's law extinction model of available radiative fluxes ( K direct′ and K diffuse′ ) and accounts for albedo-driven reflectance at the level of the snowpack. This approach is used to maintain consistency with radiation attenuation through vertical canopy layers as described in section 5.2 . Thus, The extinction coefficient K snow is input as a climate-specific default. Setting K to an arbitrary large value will ensure that all nonreflected

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Shaoping Chu, Scott Elliott, Mathew Maltrud, Jose Hernandez, and David Erickson

with POP, though the overall biogeochemistry is not yet permitted to influence physics through effects on water column radiative transfer. The lower limit for biogeochemistry modeling was set at the start of the seventh model layer, corresponding to 185-m depth. The boundary was established so that over most of the ocean, elemental cycling effects could permeate stratified waters within a few years ( Li et al., 1984 ). Biogeochemical conditions are fixed as annual averages along the deepest

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