Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

Buehler, Stefan; Defer, Éric; Evans, F.; Eliasson, Salomon; Mendrok, Jana; Eriksson, Patrick; Lee, C.; Jiménez, Carlos; Prigent, Catherine; Crewell, Susanne; Kasai, Yasuko; Bennartz, Ralf; Gasiewski, Albin J.

doi:10.5194/amtd-5-1101-2012

Cited by 8 publications

(7 citation statements)

References 55 publications

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“…[3] Visible and infrared observations of clouds have provided vast amount of information on cloud properties; however, these techniques are limited to thin clouds or to the topmost layer of clouds, hence, cannot provide much needed information on the internal structure of clouds, such as the cloud ice mass. Passive submillimeter satellite observations can penetrate through most ice clouds and provide cloud ice mass information primarily through scattering in the Rayleigh-Mie region so that cloud temperature, cloud and surface emission, and multiple scattering that affect other remote sensing techniques are relatively unimportant [e.g., Evans et al, 1998;Wu et al, 2005;Eriksson et al, 2007;Buehler et al, 2007;Jiménez et al, 2007;Buehler et al, 2012]. Furthermore, active instruments have been proven to measure cloud ice mass with high vertical resolution [Stephens et al, 2002;Winker et al, 2009;Kumagai et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

SMILES ice cloud products

et al. 2013

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[1] Upper tropospheric water vapor and clouds play an important role in Earth's climate, but knowledge of them, in particular diurnal variation in deep convective clouds, is limited. An essential variable to understand them is cloud ice water content. The Japanese Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS) samples the atmosphere at different local times allowing the study of diurnal variability of atmospheric parameters. We describe a new ice cloud data set consisting of partial Ice Water Path and Ice Water Content. Preliminary comparisons with EOS-MLS, CloudSat-CPR and CALIOP-CALIPSO are presented. Then, the diurnal variation over land and over open ocean for partial ice water path is reported. Over land, a pronounced diurnal variation peaking strongly in the afternoon/early evening was found. Over the open ocean, little temporal dependence was encountered. This data set is publicly available for download in HDF5 format.

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Section: Introductionmentioning

confidence: 99%

SMILES ice cloud products

et al. 2013

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“…Figure 1 shows the clear-sky temperature Jacobians for a tropical atmosphere to visualize the measurement altitude of the different channels. Similar discussions about the instrument fundamentals, although they do not explicitly relate to the ICI, can be found in Buehler et al (2007Buehler et al ( , 2012.…”

Section: Ice Cloud Imagermentioning

confidence: 70%

Ensemble Optimization Retrieval Algorithm of Hydrometeor Profiles for the Ice Cloud Imager Submillimeter‐Wave Radiometer

et al. 2018

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In this paper, we propose an ensemble optimization algorithm to retrieve the hydrometeor profiles for the upcoming Ice Cloud Imager submillimeter‐wave radiometer. The algorithm combines the database approach with local optimization under a framework of Bayesian Monte Carlo methodology. It first builds a retrieval database with atmospheric parameters obtained from prior information, and then it conducts ensemble optimization to minimize the cost function when too few database cases match the observations. The ensemble approach does not use the gradient information. Instead, it learns what the optimum's posterior distribution looks like, and then tries to estimate this distribution directly. The algorithm represents the unknown continuous posterior distribution with an ensemble of discrete cases, and it iteratively decreases the estimate uncertainties by generating a new ensemble from the learned distribution. Once the termination criterion is met, retrieval results and uncertainties are derived by integration over the final ensemble. We conduct retrieval experiments using simulated noisy brightness temperatures. Retrieved profiles are compared to the true values, and the results are statistically analyzed. The ensemble optimization algorithm is demonstrated to be an effective objective value minimization technique that avoids the complexity of gradient radiative transfer calculations. The algorithm also shows a satisfactory water content profile retrieval performance for frozen hydrometeors.

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“…The radiative effects of ice clouds depend on the vertically integrated and the vertical distribution of ice particle characteristics (Stephens and Webster 1984;Ackerman et al, 1988;Hartmann and Berry, 2017). The microwave radar and submillimeter-wave radiometry are two critical techniques for ice cloud remote sensing that are strongly synergistic when combined (Buehler et al, 2012). The microwave radar reflectivity constrains ice cloud microphysical quantities in a 40 vertically resolved sense while the submillimeter-wave radiometer constrains integrated mass and particle size.…”

Section: Introductionmentioning

confidence: 99%

Assessing synergistic radar and radiometer capability in retrieving ice cloud microphysics based on hybrid Bayesian algorithms

Liu

Mace

2021

Preprint

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Abstract. The 2017 National Academy of Sciences Decadal Survey highlighted several high priority objectives to be pursued during the next decadal timeframe, and the next-generation Cloud Convection Precipitation (CCP) observing system is thereby contemplated. In this study, we investigate the capability of two CCP candidates, i.e. a W-band cloud radar and a submillimeter-wave radiometer, in ice cloud remote sensing by developing hybrid Bayesian algorithms for the active-only, passive-only, and synergistic retrievals. The hybrid Bayesian algorithms combine the Bayesian MCI and optimization process to retrieve quantities and uncertainty estimates. The radar-only retrievals employ the optimal estimation methodology, while the radiometer-involved retrievals employ ensemble approaches to maximize the posterior probability density function. The a priori information is obtained from the Tropical Composition, Cloud and Climate Coupling (TC4) in situ data and CloudSat radar observations. Simulation experiments are conducted to evaluate the retrieval accuracies by comparing the retrieved parameters with known values. The experiment results suggest that the radiometer measurements possess high sensitivity for large ice cloud particles, even though the brightness temperature measurements do not contain direct information on the vertical distributions of ice cloud microphysics. The radar-only retrieval demonstrates skill in retrieving ice water content profiles, but not in retrieving number concentration profiles. The synergistic information is demonstrated to be helpful in improving retrieval accuracies, especially in terms of ice water path. The end-to-end simulation experiments also provide a framework that could be extended to the inclusion of other remote sensors to further assess the CCP observing system in future studies.

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Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

Cited by 8 publications

References 55 publications

SMILES ice cloud products

SMILES ice cloud products

Ensemble Optimization Retrieval Algorithm of Hydrometeor Profiles for the Ice Cloud Imager Submillimeter‐Wave Radiometer

Assessing synergistic radar and radiometer capability in retrieving ice cloud microphysics based on hybrid Bayesian algorithms

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