A study on the low‐altitude clouds over the Southern Ocean using the DARDAR‐MASK

Huang, Yi; Siems, Steven T.; Manton, M. J.; Protat, Alain; Delanoë, Julien

doi:10.1029/2012jd017800

Cited by 93 publications

(107 citation statements)

References 50 publications

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“…[35] The hypothesis that supercooled water exists frequently as thin layers over glaciated cloud [Rauber and Tokay, 1991] has gained some traction in the cloud remote sensing community, with merged radar/lidar/ spectroradiometer satellite products seemingly confirming this structure over the SO [Huang et al, 2012]. However, those authors note some limitations, in particular because of the deficiency in phase attribution of satellite cloud radar retrievals in the temperature range 0 ı C to -20 ı C, and the high attenuation of the lidar signal in liquid clouds.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, the profiles examined in this paper show quite a different picture of low-level SO clouds: predominantly liquid phase with a mixture of solid and liquid precipitation. The satellite radar phase-retrieval algorithm response to the high-reflectivity (i.e., large) supercooled liquid droplets is most likely to identify ice in SO clouds [Huang et al, 2012], and without a satellite lidar depolarization signal to contradict this, any merged product would be flawed.…”

Section: Discussionmentioning

confidence: 99%

“…The synergy of the "A-Train" [Stephens et al, 2002] satellites can be used to enhance the representation of cloud characteristics. Huang et al [2012] used a merged radar/lidar/spectroradiometer cloud product [Delanoë and Hogan, 2010] to perform a cloud climatology, highlighting the extensive presence of supercooled liquid clouds over the SO, particularly during summer. However, satellite retrievals of SLW presence and quantity have remained unverified by in situ observations over the SO.…”

Section: Introductionmentioning

confidence: 99%

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In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Pole‐to‐Pole Observation campaigns

Chubb

Jensen²,

Siems

et al. 2013

Geophysical Research Letters

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[1] Clouds over the Southern Ocean exist in a pristine environment that results in unique microphysical properties. However, in situ observations of these clouds are rare, and the dominant precipitation processes are unknown. Uncertainties in their life cycles and radiative properties make them interesting from a weather and climate perspective. Data from the standard cloud physics payload during the High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations global transects provide a unique snapshot the nature of low-level clouds in the Southern Ocean. High quantities of supercooled liquid water (up to 0.47 gm -3 ) were observed in clouds as cold as -22 ı C during two flights in different seasons and different meteorological conditions, supporting climatologies inferred from satellite observations. Cloud droplet concentrations were calculated from mean droplet size and liquid water concentrations, and were in the range of 30-120 cm -3 , which is fairly typical for the pristine Southern Ocean environment. Ice in nonprecipitating or lightly precipitating clouds was found to be rare, while drizzle drops with diameter greater than 100 m formed through warm rain processes were widespread. Large, pristine crystals were commonly seen in very low concentrations below cloud base. Citation: Chubb, T. H., J. B. Jensen, S. T. Siems, and M. J. Manton (2013), In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Poleto-Pole Observation (HIPPO) campaigns, Geophys. Res. Lett., 40,[5280][5281][5282][5283][5284][5285]

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Pole‐to‐Pole Observation campaigns

Chubb

Jensen²,

Siems

et al. 2013

Geophysical Research Letters

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“…A key input to the retrieval algorithm is an observational error covariance matrix, which includes both instrument and forward-model errors Hogan, 2008, 2010). The resulting DARDAR (for li-DAR + raDAR) products contain the profiles of the ice cloud related parameters on a 60 m vertical grid, which have been used in a number of studies (Bardeen et al, 2013;Battaglia and Delanoë, 2013;Ceccaldi et al, 2013;Delanoë et al, 2011Delanoë et al, , 2013Deng et al, 2013;Eliasson et al, 2012;Gayet et al, 2014;Huang et al, 2012;Jouan et al, 2012Jouan et al, , 2014Mason et al, 2014;Stein et al, 2011a, b).…”

Section: Cloudsat Geometrical Profiling Product (Geoprof)mentioning

confidence: 99%

Ice water content vertical profiles of high-level clouds: classification and impact on radiative fluxes

2015

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Abstract. In this article, we discuss the shape of ice water content (IWC) vertical profiles in high ice clouds and its effect on their radiative properties, both in short-and in long-wave bands (SW and LW). Based on the analysis of collocated satellite data, we propose a minimal set of primitive shapes (rectangular, isosceles trapezoid, lower and upper triangle), which represents the IWC profiles sufficiently well. About 75 % of all high-level ice clouds (P < 440 hPa) have an ice water path (IWP) smaller than 100 g m −2 , with a 10 % smaller contribution from single layer clouds. Most IWC profiles (80 %) can be represented by a rectangular or isosceles trapezoid shape. However, with increasing IWP, the number of lower triangle profiles (IWC rises towards cloud base) increases, reaching up to 40 % for IWP values greater than 300 g m −2 . The number of upper triangle profiles (IWC rises towards cloud top) is in general small and decreases with IWP, with the maximum occurrence of 15 % in cases of IWP less than 10 g m −2 . We propose a statistical classification of the IWC shapes using IWP as a single parameter. We have estimated the radiative effects of clouds with the same IWP and with different IWC profile shapes for five typical atmospheric scenarios and over a broad range of IWP, cloud height, cloud vertical extent, and effective ice crystal diameter (De). We explain changes in outgoing LW fluxes at the top of the atmosphere (TOA) by the cloud thermal radiance while differences in TOA SW fluxes relate to the De vertical profile within the cloud. Absolute differences in net TOA and surface fluxes associated with these parameterized IWC profiles instead of assuming constant IWC profiles are in general of the order of 1-2 W m −2 : they are negligible for clouds with IWP < 30 g m −2 , but may reach 2 W m −2 for clouds with IWP > 300 W m −2 .

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“…The DARDAR algorithm Hogan, 2008, 2010) exploits the synergy of CALIPSO and CLOUDSAT observations to retrieve vertical profiles of cloud thermodynamic phase (DARDAR-MASK product) and ice cloud properties (DARDAR-CLOUD product). These products are now widely used for cloud studies Huang et al, 2012;Jouan et al, 2012Jouan et al, , 2014. DARDAR-MASK algorithm uses Level 1B CALIPSO 532 nm lidar backscatter coefficient profiles, "2B-GEOPROF" CLOUDSAT 94 GHz radar reflectivity, as well as thermodynamic variables (pressure, temperature, humidity) from "ECMWF-AUX" products.…”

Section: Dardar Retrieval Algorithmmentioning

confidence: 99%

Variability of mixed-phase clouds in the Arctic with a focus on the Svalbard region: a study based on spaceborne active remote sensing

et al. 2015

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Abstract. The Arctic region is known to be very sensitive to climate change. Clouds and in particular mixed-phase clouds (MPCs) remain one of the greatest sources of uncertainties in the modelling of the Arctic response to climate change due to an inaccurate representation of their variability and their quantification. In this study, we present a characterisation of the vertical, spatial and seasonal variability of Arctic clouds and MPCs over the entire Arctic region based on satellite active remote sensing observations. MPC properties in the region of the Svalbard archipelago (78 • N, 15 • E) are also investigated. The occurrence frequency of clouds and MPCs are determined from CALIPSO/CLOUDSAT measurements processed with the DARDAR retrieval algorithm, which allow for a reliable cloud thermodynamic phase classification (warm liquid, supercooled liquid, ice, mixing of ice and supercooled liquid). Significant differences are observed between MPC properties over the entire Arctic region and over the Svalbard region. Results show that MPCs are encountered all year long, with a minimum occurrence of 30 % in winter and 50 % during the rest of the year on average over the entire Arctic. Over the Svalbard region, MPC occurrence is more constant with time with larger values (55 %) compared to the average observed in the Arctic. MPCs are especially located at low altitudes, below 3000 m, where their frequency of occurrence reaches 90 %, particularly during winter, spring and autumn. Moreover, results highlight that MPCs are statistically more frequent above open sea than land or sea ice. The temporal and spatial distribution of MPCs over the Svalbard region seems to be linked to the supply of moister air and warmer water from the North Atlantic Ocean, which contribute to the initiation of the liquid water phase. Over the whole Arctic, and particularly in western regions, the increase of MPC occurrence from spring to autumn could be connected to the sea ice melting. During this period, the open water transports some of the warm water from the North Atlantic Ocean to the rest of the Arctic region. This facilitates the vertical transfer of moisture and thus the persistence of the liquid phase. Particular attention is also paid to the measurement uncertainties and how they could affect our conclusions.

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A study on the low‐altitude clouds over the Southern Ocean using the DARDAR‐MASK

Cited by 93 publications

References 50 publications

In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Pole‐to‐Pole Observation campaigns

In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Pole‐to‐Pole Observation campaigns

Ice water content vertical profiles of high-level clouds: classification and impact on radiative fluxes

Variability of mixed-phase clouds in the Arctic with a focus on the Svalbard region: a study based on spaceborne active remote sensing

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