Assessment of Cloudsat Reflectivity Measurements and Ice Cloud Properties Using Ground-Based and Airborne Cloud Radar Observations

Protat, Alain; Bouniol, Dominique; Delanoë, Julien; May, Peter T.; Plana-Fattori, Artemio; Hasson, Audrey; O’Connor, Ewan; Görsdorf, Ulrich; Heymsfield, Andrew J.

doi:10.1175/2009jtecha1246.1

Cited by 119 publications

(110 citation statements)

References 42 publications

(54 reference statements)

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“…Based on previous modeling studies [Lynn et al, 2005;Khain et al, 2005;van den Heever et al, 2006van den Heever et al, , 2011Rosenfeld et al, 2008;Storer et al, 2010;Storer and van den Heever, 2013;Fan et al, 2013], we would expect an increase in cloud ice with increased aerosol amounts. However, there is some uncertainty associated with the values of ice water path due to the fact that radar-based retrievals of ice water content are sensitive to the choice of the size and density parameters used [Protat et al, 2009]. Changes in aerosol concentration can also affect the size of ice particles, and so competing effects may be leading to the lack of a consistent trend.…”

Section: Shown Inmentioning

confidence: 99%

Observations of aerosol‐induced convective invigoration in the tropical east Atlantic

2014

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Four years of CloudSat data have been analyzed over a region of the east Atlantic Ocean in order to examine the influence of aerosols on deep convection. The satellite data were combined with information about aerosols taken from the Global and Regional Earth-System Monitoring Using Satellite and In Situ Data model. Only those profiles fitting the definition of deep convective clouds were analyzed. Overall, the cloud center of gravity, cloud top, and rain top were all found to increase with increased aerosol loading. These effects were largely independent of the environment, and the differences between the cleanest and most polluted clouds sampled were found to be statistically significant. When examining an even smaller subset of deep convective clouds likely to be part of the convective core, similar trends were seen. These observations suggest that convective invigoration occurs with increased aerosol loading, leading to deeper, stronger storms in polluted environments.

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Section: Shown Inmentioning

confidence: 99%

Observations of aerosol‐induced convective invigoration in the tropical east Atlantic

2014

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“…CloudSat IWC has been validated with in situ, groundbased and other satellite IWC measurements (e.g., Austin et al, 2009;Wu et al, 2009;Protat et al, 2009). The uncertainty is claimed to be up to 40 % , which is much smaller than the divergences among various satellites and models, the latter of which often exceed 100 % Eliasson et al, 2011).…”

Section: Cloudsat Iwcmentioning

confidence: 99%

CloudSat-constrained cloud ice water path and cloud top height retrievals from MHS 157 and 183.3 GHz radiances

Gong

2014

Atmos. Meas. Tech.

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Abstract. Ice water path (IWP) and cloud top height (h t ) are two of the key variables in determining cloud radiative and thermodynamical properties in climate models. Large uncertainty remains among IWP measurements from satellite sensors, in large part due to the assumptions made for cloud microphysics in these retrievals. In this study, we develop a fast algorithm to retrieve IWP from the 157, 183.3 ± 3 and 190.3 GHz radiances of the Microwave Humidity Sounder (MHS) such that the MHS cloud ice retrieval is consistent with CloudSat IWP measurements. This retrieval is obtained by constraining the empirical forward models between collocated and coincident measurements of CloudSat IWP and MHS cloud-induced radiance depression (T cir ) at these channels. The empirical forward model is represented by a lookup table (LUT) of T cir -IWP relationships as a function of h t and the frequency channel. With h t simultaneously retrieved, the IWP is found to be more accurate. The useful range of the MHS IWP retrieval is between 0.5 and 10 kg m −2 , and agrees well with CloudSat in terms of the normalized probability density function (PDF). Compared to the empirical model, current operational radiative transfer models (RTMs) still have significant uncertainties in characterizing the observed T cir -IWP relationships. Therefore, the empirical LUT method developed here remains an effective approach to retrieving ice cloud properties from the MHS-like microwave channels.

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“…The CloudSat IWC product from 2B-CWC-RO V008 has a vertical resolution of ∼ 0.25 km and horizontal resolution of ∼ 1.1 km. Despite having been validated against aircraft measurements and many other independent observations (Protat et al, 2009;Wu et al, 2009), the CloudSat IWC product still has some known issues. Thin cirrus clouds are normally below its detection threshold, and the W-band radar tends to suffer from attenuation and/or multiple-scattering below 9 km when clouds are heavily precipitating (Protat et al, 2009).…”

Section: Data Sets Model and Methodologymentioning

confidence: 99%

“…Despite having been validated against aircraft measurements and many other independent observations (Protat et al, 2009;Wu et al, 2009), the CloudSat IWC product still has some known issues. Thin cirrus clouds are normally below its detection threshold, and the W-band radar tends to suffer from attenuation and/or multiple-scattering below 9 km when clouds are heavily precipitating (Protat et al, 2009). Austin et al (2009) estimated this IWC product uncertainty of up to ∼ 40 %, while Eliasson et al (2013) pointed out that the error could be much larger in mixed-phase clouds as well as in thin ice cloud.…”

Section: Data Sets Model and Methodologymentioning

confidence: 99%

“…CloudSat provides unprecedented quality of high-resolution ice water content (IWC) measurements for investigating cloud internal structures in the upper troposphere (UT) (Protat et al, 2009). By integrating CloudSat IWC along different slant paths, we find that ice clouds at height greater than 11 km are systematically tilted poleward from active convection centers in the tropics [30 • S, 30 • N].…”

Section: Introductionmentioning

confidence: 99%

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Meridionally tilted ice cloud structures in the tropical upper troposphere as seen by CloudSat

Gong

Wu²,

Limpasuvan³

2015

Atmos. Chem. Phys.

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Abstract. It remains challenging to quantify global cloud properties and uncertainties associated with their impacts on climate change because of our poor understanding of cloud three-dimensional (3-D) structures from observations and unrealistic characterization of 3-D cloud effects in global climate models (GCMs). In this study we find cloud 3-D effects can cause significant error in cloud ice and radiation measurements if it is not taken into account appropriately.One of the cloud 3-D complexities, the slantwise tilt structure, has not received much attention in research and even less has been reported considering a global perspective. A novel approach is presented here to analyze the ice cloud water content (IWC) profiles retrieved from CloudSat and a joint radar-lidar product (DARDAR). By integrating IWC profiles along different tilt angles, we find that uppertroposphere (UT) ice cloud mass between 11 and 17 km is tilted poleward from active convection centers in the tropics [30 • S, 30 • N]. This systematic tilt in cloud mass structure is expected from the mass conservation principle of the Hadley circulation with the divergent flow of each individual convection/convective system from down below, and its existence is further confirmed from cloud-resolving-scale Weather Research and Forecasting (WRF) model simulations. Thus, additive effects of tilted cloud structures can introduce 5-20 % variability by its nature or produce errors to satellite cloud/hydrometeor ice retrievals if simply converting it from slant to nadir column. A surprising finding is the equatorward tilt in middle tropospheric (5-11 km) ice clouds, which is also evident in high-resolution model simulations but not in coarse-resolution simulations with cumulus parameterization. The observed cloud tilt structures are intrinsic properties of tropical clouds, producing synoptic distributions around the Intertropical Convergence Zone (ITCZ). These findings imply that current interpretations based on over-simplified cloud vertical structures could lead to considerable cloud measurement errors and have a subsequent impact on understanding cloud radiative, dynamical and hydrological properties.

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Assessment of Cloudsat Reflectivity Measurements and Ice Cloud Properties Using Ground-Based and Airborne Cloud Radar Observations

Cited by 119 publications

References 42 publications

Observations of aerosol‐induced convective invigoration in the tropical east Atlantic

Observations of aerosol‐induced convective invigoration in the tropical east Atlantic

CloudSat-constrained cloud ice water path and cloud top height retrievals from MHS 157 and 183.3 GHz radiances

Meridionally tilted ice cloud structures in the tropical upper troposphere as seen by CloudSat

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