Retrieval of cirrus properties by Sun photometry: A new perspective on an old issue

Segal-Rosenheimer, Michal; Russell, Philip B.; Livingston, J. M.; Ramachandran, S.; Redemann, Jens; Baum, Bryan A.

doi:10.1002/jgrd.50185

Cited by 25 publications

(43 citation statements)

References 45 publications

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“…3.4). As expected based on previous research (e.g., DeVore et al, 2009;Segal-Rosenheimer et al, 2013) and the phase functions in Fig. 4, the ice crystal size has systematic effects on radiances in the vicinity of sun.…”

Section: Sensitivity Of the Radiances To Ice Crystal Sizessupporting

confidence: 89%

“…It is based on the conducted sensitivity tests (see Figs. 7-11 Segal-Rosenheimer et al, 2013;Reinhardt et al, 2014). The impacts on near-forward scattered radiation due to ice crystal roughness and habit have also been considered (DeVore et al, 2012;Segal-Rosenheimer et al, 2013;Reinhardt et al, 2014).…”

Section: Summary Of Sensitivity Testsmentioning

confidence: 99%

“…Although the impact of ice crystal sizes and shapes on their optical properties has been studied in much detail (Macke et al, 1998;Zhang et al, 1999;McFarquhar et al, 2002;Schlimme et al, 2005;Um and McFarquhar, 2007, 2013, there is no detailed information on how ice crystals affect the angular dependence of circumsolar radiances. However, the studies of Segal-Rosenheimer et al (2013) and Reinhardt et al (2014) have revealed that differences in the modeled forward scattering of smooth and roughened ice crystals as well as different shape distributions of ice crystals lead to differences in the circumsolar radiation. DeVore et al (2012) also noted the impact of ice crystals properties (roughness and effective radius) on calculated circumsolar radiances.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, retrievals of ice cloud optical thickness and other properties from the direct radiation measurements can be biased. There have been some efforts to quantify the amount of circumsolar radiation in the measured direct radiation and to account for its impact on the underestimation of cloud optical thickness (Shiobara and Asano, 1994;Kinne et al, 1997;Segal-Rosenheimer et al, 2013). For example Segal-Rosenheimer et al (2013) proposed a new approach to derive ice cloud optical thickness and effective diameter from sun photometry measurements by using ice cloud optical property models.…”

Section: Introductionmentioning

confidence: 99%

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Disk and circumsolar radiances in the presence of ice clouds

et al. 2017

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Abstract. The impact of ice clouds on solar disk and circumsolar radiances is investigated using a Monte Carlo radiative transfer model. The monochromatic direct and diffuse radiances are simulated at angles of 0 to 8 • from the center of the sun. Input data for the model are derived from measurements conducted during the 2010 Small Particles in Cirrus (SPAR-TICUS) campaign together with state-of-the-art databases of optical properties of ice crystals and aerosols. For selected cases, the simulated radiances are compared with groundbased radiance measurements obtained by the Sun and Aureole Measurements (SAM) instrument.First, the sensitivity of the radiances to the ice cloud properties and aerosol optical thickness is addressed. The angular dependence of the disk and circumsolar radiances is found to be most sensitive to assumptions about ice crystal roughness (or, more generally, non-ideal features of ice crystals) and size distribution, with ice crystal habit playing a somewhat smaller role. Second, in comparisons with SAM data, the ice cloud optical thickness is adjusted for each case so that the simulated radiances agree closely (i.e., within 3 %) with the measured disk radiances. Circumsolar radiances at angles larger than ≈ 3 • are systematically underestimated when assuming smooth ice crystals, whereas the agreement with the measurements is better when rough ice crystals are assumed. Our results suggest that it may well be possible to infer the particle roughness directly from ground-based SAM measurements. In addition, the results show the necessity of correcting the ground-based measurements of direct radiation for the presence of diffuse radiation in the instrument's field of view, in particular in the presence of ice clouds.

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Section: Sensitivity Of the Radiances To Ice Crystal Sizessupporting

confidence: 89%

Section: Summary Of Sensitivity Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Disk and circumsolar radiances in the presence of ice clouds

et al. 2017

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“…used AATS AOD to conduct a statistical study on the horizontal variability of AOD during both phases of ARCTAS. Segal-Rosenheimer et al (2013) used AATS measurements in ARCTAS to demonstrate a new approach to retrieving cirrus properties.…”

Section: Introductionmentioning

confidence: 99%

Comparison of MODIS 3 km and 10 km resolution aerosol optical depth retrievals over land with airborne sunphotometer measurements during ARCTAS summer 2008

Livingston¹,

Redemann²,

Shinozuka³

et al. 2014

Atmos. Chem. Phys.

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Abstract. Airborne sunphotometer measurements acquired by the NASA Ames Airborne Tracking Sunphotometer (AATS-14) aboard the NASA P-3 research aircraft are used to evaluate dark-target over-land retrievals of extinction aerosol optical depth (AOD) from spatially and temporally near-coincident measurements by the Moderate Resolution Imaging Spectroradiometer (MODIS) during the summer 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. The new MODIS Collection 6 aerosol data set includes retrievals of AOD at both 10 km × 10 km and 3 km × 3 km (at nadir) resolution. In this paper we compare MODIS and AATS AOD at 553 nm in 58 10 km and 134 3 km retrieval grid cells. These AOD values were derived from data collected over Canada on four days during short time segments of five (four Aqua and one Terra) satellite overpasses of the P-3 during low-altitude P-3 flight tracks. Three of the five MODIS-AATS coincidence events were dominated by smoke: one included a P-3 transect of a well-defined smoke plume in clear sky, but two were confounded by the presence of scattered clouds above smoke. The clouds limited the number of MODIS retrievals available for comparison, and led to MODIS AOD retrievals that underestimated the corresponding AATS values. This happened because the MODIS aerosol cloud mask selectively removed 0.5 km pixels containing smoke and clouds before the aerosol retrieval. The other two coincidences (one Terra and one Aqua) occurred during one P-3 flight on the same day and in the same general area, in an atmosphere characterized by a relatively low AOD (< 0.3), spatially homogeneous regional haze from smoke outflow with no distinguishable plume. For the ensemble data set for MODIS AOD retrievals with the highest-quality flag, MODIS AOD agrees with AATS AOD within the expected MODIS over-land AOD uncertainty in 60 % of the retrieval grid cells at 10 km resolution and 69 % at 3 km resolution. These values improve to 65 % and 74 %, respectively, when the cloud-affected case with the strongest plume is excluded. We find that the standard MODIS dark-target over-land retrieval algorithm fails to retrieve AOD for thick smoke, not only in cloud-contaminated regions but also in clear sky. We attribute this to deselection, by the cloud and/or bright surface masks, of 0.5 km resolution pixels that contain smoke.

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Hyperspectral aerosol optical depths from TCAP flights

et al. 2013

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[1] The 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research), a hyperspectral airborne Sun photometer, acquired aerosol optical depths (AOD) at 1 Hz during all July 2012 flights of the Two-Column Aerosol Project. Root-mean-square differences from Aerosol Robotic Network ground-based observations were 0.01 at wavelengths between 500-1020 nm, 0.02 at 380 and 1640 nm, and 0.03 at 440 nm in four clear-sky fly-over events, and similar in ground side-by-side comparisons. Changes in the above-aircraft AOD across 3 km deep spirals were typically consistent with integrals of coincident in situ (on Department of Energy Gulfstream 1 with 4STAR) and lidar (on NASA B200) extinction measurements within 0.01, 0.03, 0.01, 0.02, 0.02, and 0.02 at 355, 450, 532, 550, 700, and 1064 nm, respectively, despite atmospheric variations and combined measurement uncertainties. Finer vertical differentials of the 4STAR measurements matched the in situ ambient extinction profile within 14% for one homogeneous column. For the AOD observed between 350 and 1660 nm, excluding strong water vapor and oxygen absorption bands, estimated uncertainties were~0.01 and dominated by (then) unpredictable throughput changes, up to ±0.8%, of the fiber optic rotary joint. The favorable intercomparisons herald 4STAR's spatially resolved high-frequency hyperspectral products as a reliable tool for climate studies and satellite validation.

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Retrieval of cirrus properties by Sun photometry: A new perspective on an old issue

Cited by 25 publications

References 45 publications

Disk and circumsolar radiances in the presence of ice clouds

Disk and circumsolar radiances in the presence of ice clouds

Comparison of MODIS 3 km and 10 km resolution aerosol optical depth retrievals over land with airborne sunphotometer measurements during ARCTAS summer 2008

Hyperspectral aerosol optical depths from TCAP flights

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