MODTRAN6: a major upgrade of the MODTRAN radiative transfer code

Berk, Alexander; Conforti, Patrick F.; Kennett, R.; Perkins, Timothy; Hawes, Frederick; Bosch, Jeannette van den

doi:10.1117/12.2050433

Cited by 214 publications

(152 citation statements)

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“…Several radiative transfer models (RTMs) exist for snow, the most well known being the two-stream radiative flux models SNICAR and TARTES , and the plane-parallel multistream DIScrete Ordinates Radiative Transfer scheme (DISORT, Stamnes et al, 1988) used by the MODTRAN (Berk et al, 2014) and SBDART (Ricchiazzi et al, 1998) atmospheric transmission models. The two stream approach is computationally efficient and able to accurately predict spectral reflectance hemispherically; however, a multistream approach is required to predict directional reflectance.…”

Section: Radiative Transfer Modellingmentioning

confidence: 99%

Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo

et al. 2017

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Abstract. The darkening effects of biological impurities on ice and snow have been recognised as a control on the surface energy balance of terrestrial snow, sea ice, glaciers and ice sheets. With a heightened interest in understanding the impacts of a changing climate on snow and ice processes, quantifying the impact of biological impurities on ice and snow albedo ("bioalbedo") and its evolution through time is a rapidly growing field of research. However, rigorous quantification of bioalbedo has remained elusive because of difficulties in isolating the biological contribution to ice albedo from that of inorganic impurities and the variable optical properties of the ice itself. For this reason, isolation of the biological signature in reflectance data obtained from aerial/orbital platforms has not been achieved, even when ground-based biological measurements have been available. This paper provides the cell-specific optical properties that are required to model the spectral signatures and broadband darkening of ice. Applying radiative transfer theory, these properties provide the physical basis needed to link biological and glaciological ground measurements with remotely sensed reflectance data. Using these new capabilities we confirm that biological impurities can influence ice albedo, then we identify 10 challenges to the measurement of bioalbedo in the field with the aim of improving future experimental designs to better quantify bioalbedo feedbacks. These challenges are (1) ambiguity in terminology, (2) characterising snow or ice optical properties, (3) characterising solar irradiance, (4) determining optical properties of cells, (5) measuring biomass, (6) characterising vertical distribution of cells, (7) characterising abiotic impurities, (8) surface anisotropy, (9) measuring indirect albedo feedbacks, and (10) measurement and instrument configurations. This paper aims to provide a broad audience of glaciologists and biologists with an overview of radiative transfer and albedo that could support future experimental design.

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Section: Radiative Transfer Modellingmentioning

confidence: 99%

Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo

et al. 2017

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“…Schläpfer, Langeggweg, Switzerland) program for wide FOV airborne optical scanner data [16,17]. Atmospheric corrections were applied using atmospheric functions supplied from the MODerate resolution TRANsmission model (MODTRAN, Spectral Sciences, Burlington, MA, USA) [18,19].…”

Section: Surface Reflectance From Hyplantmentioning

confidence: 99%

The 2013 FLEX—US Airborne Campaign at the Parker Tract Loblolly Pine Plantation in North Carolina, USA

Middleton¹,

Rascher

Corp

et al. 2017

Remote Sensing

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Abstract:The first European Space Agency (ESA) and NASA collaboration in an airborne campaign to support ESA's FLuorescence EXplorer (FLEX) mission was conducted in North Carolina, USA during September-October 2013 (FLEX-US 2013) at the Parker Tract Loblolly Pine (LP) Plantation (Plymouth, NC, USA). This campaign combined two unique airborne instrument packages to obtain simultaneous observations of solar-induced fluorescence (SIF), LiDAR-based canopy structural information, visible through shortwave infrared (VSWIR) reflectance spectra, and surface temperature, to advance vegetation studies of carbon cycle dynamics and ecosystem health. We obtained statistically significant results for fluorescence, canopy temperature, and tower fluxes from data collected at four times of day over two consecutive autumn days across an age class chronosequence. Both the red fluorescence (F685) and far-red fluorescence (F740) radiances had highest values at mid-day, but their fluorescence yields exhibited different diurnal responses across LP age classes. The diurnal trends for F685 varied with forest canopy temperature difference (canopy minus air), having a stronger daily amplitude change for young vs. old canopies. The Photochemical Reflectance Index (PRI) was positively correlated with this temperature variable over the diurnal cycle. Tower measurements from mature loblolly stand showed the red/far-red fluorescence ratio was linearly related to canopy light use efficiency (LUE) over the diurnal cycle, but performed even better Remote Sens. 2017, 9, 612; doi:10.3390/rs9060612www.mdpi.com/journal/remotesensing Remote Sens. 2017, 9, 612 2 of 31 for the combined morning/afternoon (without midday) observations. This study demonstrates the importance of diurnal observations for interpretation of fluorescence dynamics, the need for red fluorescence to understand canopy physiological processes, and the benefits of combining fluorescence, reflectance, and structure information to clarify canopy function versus structure characteristics for a coniferous forest.

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“…At the ON and OFF wavelengths selected for this experiment, the differential cross section of CO 2 is five orders of magnitude larger than that of H 2 O (Rothman et al, 2013). Considering a CO 2 mixing ratio of 400 ppm, and with the upper and lower ranges of H 2 O mixing ratios used in atmospheric models (Berk et al, 2014), i.e., from 2.59% (tropics, sea level) to 0.141% (high latitude, winter, sea level), the respective CO 2 absorption is 3 and 5 orders of magnitude larger than that of H 2 O. The 2.59% H 2 O mixing ratio is not far from the saturated water vapor pressure at standard atmospheric conditions.…”

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confidence: 99%

New Advances in Dial-Lidar-Based Remote Sensing of the Volcanic CO2 Flux

et al. 2017

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We report here on the results of a proof-of-concept study aimed at remotely sensing the volcanic CO 2 flux using a Differential Adsorption lidar (DIAL-lidar). The observations we report on were conducted in June 2014 on Stromboli volcano, where our lidar (LIght Detection And Ranging) was used to scan the volcanic plume at ∼3 km distance from the summit vents. The obtained results prove that a remotely operating lidar can resolve a volcanic CO 2 signal of a few tens of ppm (in excess to background air) over km-long optical paths. We combine these results with independent estimates of plume transport speed (from processing of UV Camera images) to derive volcanic CO 2 flux time-series of ≈16-33 min temporal resolution. Our lidar-based CO 2 fluxes range from 1.8 ± 0.5 to 32.1 ± 8.0 kg/s, and constrain the daily averaged CO 2 emissions from Stromboli at 8.3 ± 2.1 to 18.1 ± 4.5 kg/s (or 718-1565 tons/day). These inferred fluxes fall within the range of earlier observations at Stromboli. They also agree well with contemporaneous CO 2 flux determinations (8.4-20.1 kg/s) obtained using a standard approach that combines Multi-GAS-based in-plume readings of the CO 2 /SO 2 ratio (≈8) with UV-camera sensed SO 2 fluxes (1.5-3.4 kg/s). We conclude that DIAL-lidars offer new prospects for safer (remote) instrumental observations of the volcanic CO 2 flux.Keywords: volcanic CO 2 , DIAL-lidar, Stromboli, remote sensing, CO 2 flux INTRODUCTION A major step forward in ground-based volcano monitoring has recently arisen from the advent of modern instrumental techniques and networks for volcanic gas observations (Galle et al., 2010;Oppenheimer et al., 2014;Saccorotti et al., 2014;Fischer and Chiodini, 2015). Such technical advances provide improved temporal resolution relative to traditional direct sampling techniques (Symonds et al., 1994;Giggenbach, 1996). As longer-term volcanic gas records increase in number and quality, full empirical evidence is finally emerging for increased CO 2 flux emissions prior to eruption of mafic to intermediate volcanoes (Aiuppa, 2015). Precursory plume CO 2 flux increases have been now detected at several volcanoes, including Etna (Aiuppa et al., 2008;Patanè et al., 2013), Kilauea (Poland et al., 2012), Redoubt (Werner et al., 2013), Turrialba (de Moor et al., 2016a), and Poas (de Moor et al., 2016b).At Stromboli (in Italy), however, CO 2 flux observations have been particularly valuable for interpreting, and eventually predicting, the volcano's behavior (Aiuppa et al., 2010a Stromboli, the "regular" mild strombolian activity is occasionally interrupted by larger-scale vulcanian-style explosions, locally referred as "major explosions" or (in the most extreme events) "paroxysms" (Rosi et al., 2006(Rosi et al., , 2013Andronico and Pistolesi, 2010;Pistolesi et al., 2011;Pioli et al., 2014). These explosions, although short-lived (tens of seconds to a few minutes), represent a real hazard for local populations, tourists and volcanologists, since they produce fallout of coarse pyroclastic materials over w...

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MODTRAN6: a major upgrade of the MODTRAN radiative transfer code

Cited by 214 publications

References 4 publications

Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo

Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo

The 2013 FLEX—US Airborne Campaign at the Parker Tract Loblolly Pine Plantation in North Carolina, USA

New Advances in Dial-Lidar-Based Remote Sensing of the Volcanic CO2 Flux

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