Reference solar irradiance spectra and consequences of their disparities in remote sensing of the ocean colour

Shanmugam, Palanisamy; Ahn, Yu-Hwan

doi:10.5194/angeo-25-1235-2007

Cited by 19 publications

(16 citation statements)

References 39 publications

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“…To this effect, the scheme computes the OSA from λ 1 = 200 to λ 2 = 4000 nm with a resolution of 10 nm. The contribution of each wavelength interval dλ to OSA is weighted by its amount of solar energy under the standard solar spectra ASTM E-490 AM0 (Shanmugam and Ahn, 2007), E (λ) assumption as follows. (2001) in blue and that of Frigaard et al (1996) in red, which is used in the new interactive OSA scheme.…”

Section: Computation Of Osamentioning

confidence: 99%

An interactive ocean surface albedo scheme (OSAv1.0): formulation and evaluation in ARPEGE-Climat (V6.1) and LMDZ (V5A)

et al. 2018

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Abstract. Ocean surface represents roughly 70 % of the Earth's surface, playing a large role in the partitioning of the energy flow within the climate system. The ocean surface albedo (OSA) is an important parameter in this partitioning because it governs the amount of energy penetrating into the ocean or reflected towards space. The old OSA schemes in the ARPEGE-Climat and LMDZ models only resolve the latitudinal dependence in an ad hoc way without an accurate representation of the solar zenith angle dependence. Here, we propose a new interactive OSA scheme suited for Earth system models, which enables coupling between Earth system model components like surface ocean waves and marine biogeochemistry. This scheme resolves spectrally the various contributions of the surface for direct and diffuse solar radiation. The implementation of this scheme in two Earth system models leads to substantial improvements in simulated OSA. At the local scale, models using the interactive OSA scheme better replicate the day-to-day distribution of OSA derived from ground-based observations in contrast to old schemes. At global scale, the improved representation of OSA for diffuse radiation reduces model biases by up to 80 % over the tropical oceans, reducing annual-mean modeldata error in surface upwelling shortwave radiation by up to 7 W m −2 over this domain. The spatial correlation coefficient between modeled and observed OSA at monthly resolution has been increased from 0.1 to 0.8. Despite its complexity, this interactive OSA scheme is computationally efficient for enabling precise OSA calculation without penalizing the elapsed model time.

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Section: Computation Of Osamentioning

confidence: 99%

An interactive ocean surface albedo scheme (OSAv1.0): formulation and evaluation in ARPEGE-Climat (V6.1) and LMDZ (V5A)

et al. 2018

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“…-Solar constant of 1365.5 Wm −2 for 2006 (Shanmugam and Ahn, 2007) corrected to day 139 of year (19 May).…”

Section: The Assumed Scenariosmentioning

confidence: 99%

On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations

Otto

Trautmann²,

Wendisch

2011

Atmos. Chem. Phys.

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Abstract. Realistic size equivalence and shape of Saharan mineral dust particles are derived from in-situ particle, lidar and sun photometer measurements during SAMUM-1 in Morocco (19 May 2006), dealing with measured sizeand altitude-resolved axis ratio distributions of assumed spheroidal model particles. The data were applied in optical property, radiative effect, forcing and heating effect simulations to quantify the realistic impact of particle nonsphericity. It turned out that volume-to-surface equivalent spheroids with prolate shape are most realistic: particle nonsphericity only slightly affects single scattering albedo and asymmetry parameter but may enhance extinction coefficient by up to 10 %. At the bottom of the atmosphere (BOA) the Saharan mineral dust always leads to a loss of solar radiation, while the sign of the forcing at the top of the atmosphere (TOA) depends on surface albedo: solar cooling/warming over a mean ocean/land surface. In the thermal spectral range the dust inhibits the emission of radiation to space and warms the BOA. The most realistic case of particle non-sphericity causes changes of total (solar plus thermal) forcing by 55/5 % at the TOA over ocean/land and 15 % at the BOA over both land and ocean and enhances total radiative heating within the dust plume by up to 20 %. Large dust particles significantly contribute to all the radiative effects reported. They strongly enhance the absorbing properties and forward scattering in the solar and increase predominantly, e.g., the total TOA forcing of the dust over land.

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“…Some scholars have conducted detailed intercomparisons between spectra, producing useful results and suggestions [7], [10], [12], [14], [17], [30]. The differences between solar irradiance spectra and their effect on vicarious calibration and ocean color have been evaluated by other authors [8], [18], [23]. Such studies have shown that significant variations exist between solar irradiance models and could influence the results of certain applications.…”

Section: Introductionmentioning

confidence: 99%

“…Numerous solar irradiance spectra data have been collected over the last several decades [5], [9], [10], [13], [14], [16]- [18], [24]- [28], [30]. These spectra have generally been compiled using data recorded by various types of instruments with differences in calibration and spectral resolution, in different spectral regions, and on different platforms and at different times.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Solar Irradiance Spectra on Calculation of Narrow Band Top-of-Atmosphere Reflectance

Zhang

Yang

et al. 2014

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Extraterrestrial solar irradiance spectra detail the solar energy distribution over wavelengths, and numerous solar irradiance models are available within the remote sensing community. However, reference spectra may differ widely owing to differences in solar activity, measurement instruments and calibration. Six widely referenced solar spectra were selected in this work to examine their differences and the impacts of these differences on calculations of narrow band top-of-atmosphere reflectance using MERIS and Hyperion hyperspectral sensor spectral configurations. Mean solar exoatmospheric irradiance (MSEI) was computed using the different solar irradiance models and spectral response functions of the MERIS and Hyperion hyperspectral sensors. Then, the effects of MSEI on top-of-atmosphere (TOA) reflectance and the normalized difference vegetation index (NDVI) and atmospherically resistant vegetation index (ARVI) were investigated. The results show that the six selected solar irradiance models have significant differences from 350 to 2500 nm, which in turn result in differences in the MSEI derived from MERIS and Hyperion observations. These differences have a less significant effect on the TOA reflectance in the visible and near-infrared bands and on NDVI. However, the differences result in large differences in TOA reflectance in the infrared bands and in ARVI.

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Reference solar irradiance spectra and consequences of their disparities in remote sensing of the ocean colour

Cited by 19 publications

References 39 publications

An interactive ocean surface albedo scheme (OSAv1.0): formulation and evaluation in ARPEGE-Climat (V6.1) and LMDZ (V5A)

An interactive ocean surface albedo scheme (OSAv1.0): formulation and evaluation in ARPEGE-Climat (V6.1) and LMDZ (V5A)

On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations

The Effects of Solar Irradiance Spectra on Calculation of Narrow Band Top-of-Atmosphere Reflectance

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