Retrieval of Cloud Properties Using CALIPSO Imaging Infrared Radiometer. Part II: Effective Diameter and Ice Water Path

Garnier, Anne; Pelon, Jacques; Dubuisson, Philippe; Yang, Ping; Faivre, M.; Chomette, Olivier; Pascal, Nicolas; Lucker, Patricia L.; Murray, Tim

doi:10.1175/jamc-d-12-0328.1

Cited by 54 publications

(74 citation statements)

References 37 publications

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“…Another estimate of r ei is derived from a combination of the CloudAerosol Lidar with Orthogonal Polarization (CALIOP) and the Imaging Infrared Radiometer (IIR) instruments (Garnier et al, 2013) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite (Winker et al, 2010). Additional active-passive algorithms are also available.…”

Section: Introductionmentioning

confidence: 99%

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

et al. 2018

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Abstract. We use the Atmospheric Infrared Sounder (AIRS) version 6 ice cloud property and thermodynamic phase retrievals to quantify variability and 14-year trends in ice cloud frequency, ice cloud top temperature (T ci ), ice optical thickness (τ i ) and ice effective radius (r ei ). The trends in ice cloud properties are shown to be independent of trends in information content and χ 2 . Statistically significant decreases in ice frequency, τ i , and ice water path (IWP) are found in the SH and NH extratropics, but trends are of much smaller magnitude and statistically insignificant in the tropics. However, statistically significant increases in r ei are found in all three latitude bands. Perturbation experiments consistent with estimates of AIRS radiometric stability fall significantly short of explaining the observed trends in ice properties, averaging kernels, and χ 2 trends. Values of r ei are larger at the tops of opaque clouds and exhibit dependence on surface wind speed, column water vapour (CWV) and surface temperature (T sfc ) with changes up to 4-5 µm but are only 1.9 % of all ice clouds. Non-opaque clouds exhibit a much smaller change in r ei with respect to CWV and T sfc . Comparisons between DARDAR and AIRS suggest that r ei is smallest for singlelayer cirrus, larger for cirrus above weak convection, and largest for cirrus above strong convection at the same cloud top temperature. This behaviour is consistent with enhanced particle growth from radiative cooling above convection or large particle lofting from strong convection.

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Section: Introductionmentioning

confidence: 99%

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

et al. 2018

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“…However, several studies (Cooper et al, 2007;Cooper and Garrett, 2010;Wang et al, 2011) have shown that cirrus optical properties may be retrieved with a better accuracy using a combination of TIR channels instead of visible and near-infrared (VNIR) channels (such as the Nakajima and King method, Nakajima and King, 1990), as long as the cirrus is optically thin enough (with a visible optical thickness between roughly 0.5 and 3) and the CED is smaller than 40 µm. For example the split-window technique (Inoue, 1985) applied to the Advanced Very-High-Resolution Radiometer (AVHRR; Parol et al, 1991) and the Imaging Infrared Radiometer (IIR) onboard CALIPSO (Garnier et al, 2012(Garnier et al, , 2013) is used to retrieve CED and COT from the brightness temperature difference of two different channels in the infrared atmospheric windows where gaseous absorption is small. Based on the same spectral information, an optimal estimation method (OEM; Rodgers, 2000) is used for the Atmospheric Infrared Sounder V6 (AIRS, Kahn et al, 2014Kahn et al, , 2015) and in the research-level code of Wang et al (2016b, a) for MODIS.…”

Section: Introductionmentioning

confidence: 99%

Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements – Part I: MODIS brightness temperatures in the thermal infrared

et al. 2017

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Abstract. This paper presents a study on the impact of cirrus cloud heterogeneities on MODIS simulated thermal infrared (TIR) brightness temperatures (BTs) at the top of the atmosphere (TOA) as a function of spatial resolution from 50 m to 10 km. A realistic 3-D cirrus field is generated by the 3DCLOUD model (average optical thickness of 1.4, cloudtop and base altitudes at 10 and 12 km, respectively, consisting of aggregate column crystals of D eff = 20 µm), and 3-D thermal infrared radiative transfer (RT) is simulated with the 3DMCPOL code. According to previous studies, differences between 3-D BT computed from a heterogenous pixel and 1-D RT computed from a homogeneous pixel are considered dependent at nadir on two effects: (i) the optical thickness horizontal heterogeneity leading to the plane-parallel homogeneous bias (PPHB) and the (ii) horizontal radiative transport (HRT) leading to the independent pixel approximation error (IPAE). A single but realistic cirrus case is simulated and, as expected, the PPHB mainly impacts the low-spatialresolution results (above ∼ 250 m) with averaged values of up to 5-7 K, while the IPAE mainly impacts the high-spatialresolution results (below ∼ 250 m) with average values of up to 1-2 K. A sensitivity study has been performed in order to extend these results to various cirrus optical thicknesses and heterogeneities by sampling the cirrus in several ranges of parameters. For four optical thickness classes and four optical heterogeneity classes, we have found that, for nadir observations, the spatial resolution at which the combination of PPHB and HRT effects is the smallest, falls between 100 and 250 m. These spatial resolutions thus appear to be the best choice to retrieve cirrus optical properties with the smallest cloud heterogeneity-related total bias in the thermal infrared. For off-nadir observations, the average total effect is increased and the minimum is shifted to coarser spatial resolutions.

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“…Global satellite observations are well suited to monitoring and investigating cloud evolution and characteristicsm because passive top-of-atmosphere (TOA) radiometric measurements allow for retrievals of cloud properties such as optical thickness and ice crystal effective diameter. In this work, we focus on infrared measurements obtained by the Imaging Infrared Radiometer (IIR; Garnier et al, 2012Garnier et al, , 2013 onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO).…”

Section: Introductionmentioning

confidence: 99%

Impacts of cloud heterogeneities on cirrus optical properties retrieved from space-based thermal infrared radiometry

et al. 2015

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Abstract. This paper presents a study, based on simulations, of the impact of cirrus cloud heterogeneities on the retrieval of cloud parameters (optical thickness and effective diameter) for the Imaging Infrared Radiometer (IIR) on board CALIPSO. Cirrus clouds are generated by the stochastic model 3DCLOUD for two different cloud fields and for several averaged cloud parameters. One cloud field is obtained from a cirrus observed on 25 May 2007 during the airborne campaign CIRCLE-2 and the other is a cirrus uncinus. The radiative transfer is simulated with the 3DMCPOL code. To assess the errors due to cloud heterogeneities, two related retrieval algorithms are used: (i) the split-window technique to retrieve the ice crystal effective diameter and (ii) an algorithm similar to the IIR operational algorithm to retrieve the effective emissivity and the effective optical thickness. Differences between input parameters and retrieved parameters are compared as a function of different cloud properties such as the mean optical thickness, the heterogeneity parameter and the effective diameter. The optical thickness heterogeneity for each 1 km × 1 km observation pixel is represented by the optical thickness standard deviation computed using 100 m × 100 m subpixels. We show that optical thickness heterogeneity may have a strong impact on the retrieved parameters, mainly due to the plane-parallel approximation (PPA assumption). In particular, for cirrus clouds with ice crystal diameter of approximately 10 µm, the averaged error on the retrieved effective diameter and optical thickness is about 2.5 µm (∼ 25 %) and −0.20 (∼ 12 %), respectively. Then, these biases decrease with increasing effective size due to a decrease of the cloud absorption and, thus, the PPA bias. Cloud horizontal heterogeneity effects are greater than other possible sources of retrieval errors such as those due to cloud vertical heterogeneity impact, surface temperature or atmospheric temperature profile uncertainty and IIR retrieval uncertainty. Cloud horizontal heterogeneity effects are larger than the IIR retrieval uncertainty if the standard deviation of the optical thickness, inside the observation pixel, is greater than 1.

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Retrieval of Cloud Properties Using CALIPSO Imaging Infrared Radiometer. Part II: Effective Diameter and Ice Water Path

Cited by 54 publications

References 37 publications

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements – Part I: MODIS brightness temperatures in the thermal infrared

Impacts of cloud heterogeneities on cirrus optical properties retrieved from space-based thermal infrared radiometry

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