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Book ; Online: Simulation of mixed-phase clouds with the ICON large-eddy model in the complex Arctic environment around Ny-Ålesund

Schemann, Vera / Ebell, Kerstin

eISSN: 1680-7324

2020

Abstract: Low-level mixed-phase clouds have a substantial impact on the redistribution of radiative energy in the Arctic and are a potential driving factor in Arctic amplification. To better understand the complex processes around mixed-phase clouds, a combination ...

Abstract	Low-level mixed-phase clouds have a substantial impact on the redistribution of radiative energy in the Arctic and are a potential driving factor in Arctic amplification. To better understand the complex processes around mixed-phase clouds, a combination of long-term measurements and high-resolution modeling able to resolve the relevant processes is essential. In this study, we show the general feasibility of the new high-resolution icosahedral nonhydrostatic large-eddy model (ICON-LEM) to capture the general structure, type and timing of mixed-phase clouds at the Arctic site Ny-Ålesund and its potential and limitations for further detailed research. To serve as a basic evaluation, the model is confronted with data streams of single instruments including a microwave radiometer and cloud radar and also with value-added products like the CloudNet classification. The analysis is based on a 11 d long time period with selected periods studied in more detail focusing on the representation of particular cloud processes, such as mixed-phase microphysics. In addition, targeted statistical evaluations against observational data sets are performed to assess (i) how well the vertical structure of the clouds is represented and (ii) how much information is added by higher horizontal resolutions. The results clearly demonstrate the advantage of high resolutions. In particular, with the highest horizontal model resolution of 75 m, the variability of the liquid water path can be well captured. By comparing neighboring grid cells for different subdomains, we also show the potential of the model to provide information on the representativity of single sites (such as Ny-Ålesund) for a larger domain.
Subject code	551
Language	English
Publishing date	2020-01-14
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Simulation of mixed-phase clouds with the ICON-LEM in the complex Arctic environment around Ny-Ålesund

Schemann, Vera / Ebell, Kerstin

eISSN: 1680-7324

2019

Abstract: Low-level mixed phase clouds have a substantial impact on the redistribution of radiative energy in the Arctic and are a potential driving factor for Arctic Amplification. To better understand the complex processes around mixed-phase clouds, a ... ...

Abstract	Low-level mixed phase clouds have a substantial impact on the redistribution of radiative energy in the Arctic and are a potential driving factor for Arctic Amplification. To better understand the complex processes around mixed-phase clouds, a combination of long-term measurements and high-resolution modeling - which is able to resolve the relevant processes - is essential. In this study, we show the general feasibility of the new high-resolution model ICON-LEM to capture the general structure, type and timing of mixed-phase clouds at the Arctic site Ny-Ålesund and its potential and limitations for further detailed research. As a basic evaluation the model is confronted with data streams of single instruments including microwave radiometer and cloud radar, but also with value added products like the Cloudnet classification. The analysis is based on a 11-day long time period with selected periods being studied in more detail focusing on the representation of particular cloud processes, such as mixed-phase microphysics. In addition, targeted statistical evaluations against observational data sets are performed to assess i) how well the vertical structure of the clouds is represented and ii) how much information is added by higher resolutions. The results clearly demonstrate the advantage of high resolutions: in particular, with the highest model resolution of 75 m, the variability of liquid water path can be well captured. By comparing neighboring grid cells for different subdomains we also show the potential of the model to provide information on the representativity of single sites (as Ny-Ålesund) for a larger domain.
Subject code	551
Language	English
Publishing date	2019-06-27
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Atmospheric temperature, water vapour and liquid water path from two microwave radiometers during MOSAiC.

Walbröl, Andreas / Crewell, Susanne / Engelmann, Ronny / Orlandi, Emiliano / Griesche, Hannes / Radenz, Martin / Hofer, Julian / Althausen, Dietrich / Maturilli, Marion / Ebell, Kerstin

Scientific data

2022 Volume 9, Issue 1, Page(s) 534

Abstract: The microwave radiometers HATPRO (Humidity and Temperature Profiler) and MiRAC-P (Microwave Radiometer for Arctic Clouds - Passive) continuously measured radiation emitted from the atmosphere throughout the Multidisciplinary drifting Observatory for the ... ...

Abstract	The microwave radiometers HATPRO (Humidity and Temperature Profiler) and MiRAC-P (Microwave Radiometer for Arctic Clouds - Passive) continuously measured radiation emitted from the atmosphere throughout the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) expedition on board the research vessel Polarstern. From the measured brightness temperatures, we have retrieved atmospheric variables using statistical methods in a temporal resolution of 1 s covering October 2019 to October 2020. The integrated water vapour (IWV) is derived individually from both radiometers. In addition, we present the liquid water path (LWP), temperature and absolute humidity profiles from HATPRO. To prove the quality and to estimate uncertainty, the data sets are compared to radiosonde measurements from Polarstern. The comparison shows an extremely good agreement for IWV, with standard deviations of 0.08-0.19 kg m
Language	English
Publishing date	2022-09-01
Publishing country	England
Document type	Journal Article
ZDB-ID	2775191-0
ISSN	2052-4463 ; 2052-4463
ISSN (online)	2052-4463
ISSN	2052-4463
DOI	10.1038/s41597-022-01504-1
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Book ; Online: DeepPrecip

King, Fraser / Duffy, George / Milani, Lisa / Fletcher, Christopher G. / Pettersen, Claire / Ebell, Kerstin

eISSN:

A deep neural network for precipitation retrievals

2022

Abstract: Remotely-sensed precipitation retrievals are critical for advancing our understanding of global energy and hydrologic cycles in remote regions. Radar reflectivity profiles of the lower atmosphere are commonly linked to precipitation through empirical ... ...

Abstract	Remotely-sensed precipitation retrievals are critical for advancing our understanding of global energy and hydrologic cycles in remote regions. Radar reflectivity profiles of the lower atmosphere are commonly linked to precipitation through empirical power laws, but these relationships are tightly coupled to particle microphysical assumptions that do not generalize well to different regional climates. Here, we develop a robust, highly generalized precipitation retrieval from a deep convolutional neural network (DeepPrecip) to estimate 20-minute average surface precipitation accumulation using near-surface radar data inputs. DeepPrecip displays high retrieval skill and can accurately model total precipitation accumulation, with a mean square error (MSE) 99 % lower, on average, than current methods. DeepPrecip also outperforms a less complex machine learning retrieval algorithm, demonstrating the value of deep learning when applied to precipitation retrievals. Predictor importance analyses suggest that a combination of both near-surface (below 1 km) and higher-altitude (1.5 – 2 km) radar measurements are the primary features contributing to retrieval accuracy. Further, DeepPrecip closely captures total precipitation accumulation magnitudes and variability across nine distinct locations without requiring any explicit descriptions of particle microphysics or geospatial covariates. This research reveals the important role for deep learning in extracting relevant information about precipitation from atmospheric radar retrievals.
Subject code	910
Language	English
Publishing date	2022-06-16
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online ; Thesis: Characterization of clouds and their radiative effects using ground based instrumentation at a low mountain site

Ebell, Kerstin

2010

Abstract: The interaction of clouds with radiation and aerosols is the greatest source of uncertainty in future climate projections. Part of the reason is the limited amount of observations of clouds and hence the limited knowledge of cloud macro- and ... ...

Author's details	vorgelegt von Kerstin Ebell
Abstract	The interaction of clouds with radiation and aerosols is the greatest source of uncertainty in future climate projections. Part of the reason is the limited amount of observations of clouds and hence the limited knowledge of cloud macro- and microphysical statistics in connection to their effects on the radiative budget and on the vertical redistribution of energy within the atmosphere. In 2007, the Atmospheric Radiation Measurement programs (ARM) Mobile Facility (AMF) was operated for a nine-month period in the Murg Valley, Black Forest, Germany, in support of the Convective and Orographically-induced Precipitation Study (COPS). Based on the measurements of the AMF and COPS partner instrumentation, the present study aims at improving the data basis of cloud macro- and microphysical statistics and to assess the potential of the derived cloud properties to estimate the radiative effects of clouds. The synergy of various instruments is exploited to derive a data set of high quality thermodynamic and cloud property profiles with a temporal resolution of 30 s. While quality filters in the cloud microphysical retrieval techniques mostly affect the representativity of ice and mixed clouds in the data sample, water clouds are very well represented in the derived 364,850 atmospheric profiles ...
Language	English ; German
Size	Online-Ressource (PDF-Datei: 141 S., 2949 KB)
Publisher	Niedersächsische Staats- und Universitätsbibliothek
Publishing place	Göttingen
Document type	Book ; Online ; Thesis
Thesis / German Habilitation thesis	Univ., Diss.--Köln, 2010
Note	Zsfassung in dt. Sprache
Database	Former special subject collection: coastal and deep sea fishing

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Book ; Online ; Thesis: Characterization of clouds and their radiative effects using ground based instrumentation at a low mountain site

Ebell, Kerstin

2010

Author's details	vorgelegt von Kerstin Ebell
Abstract	The interaction of clouds with radiation and aerosols is the greatest source of uncertainty in future climate projections. Part of the reason is the limited amount of observations of clouds and hence the limited knowledge of cloud macro- and microphysical statistics in connection to their effects on the radiative budget and on the vertical redistribution of energy within the atmosphere. In 2007, the Atmospheric Radiation Measurement programs (ARM) Mobile Facility (AMF) was operated for a nine-month period in the Murg Valley, Black Forest, Germany, in support of the Convective and Orographically-induced Precipitation Study (COPS). Based on the measurements of the AMF and COPS partner instrumentation, the present study aims at improving the data basis of cloud macro- and microphysical statistics and to assess the potential of the derived cloud properties to estimate the radiative effects of clouds. The synergy of various instruments is exploited to derive a data set of high quality thermodynamic and cloud property profiles with a temporal resolution of 30 s. While quality filters in the cloud microphysical retrieval techniques mostly affect the representativity of ice and mixed clouds in the data sample, water clouds are very well represented in the derived 364,850 atmospheric profiles ...
Language	English ; German
Size	Online-Ressource (PDF-Datei: 141 S., 2949 KB)
Publisher	Niedersächsische Staats- und Universitätsbibliothek
Publishing place	Göttingen
Document type	Book ; Online ; Thesis
Thesis / German Habilitation thesis	Univ., Diss.--Köln, 2010
Note	Zsfassung in dt. Sprache
Database	Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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Book ; Online: Low-level mixed-phase clouds at the high Arctic site of Ny-Ålesund

Chellini, Giovanni / Gierens, Rosa / Ebell, Kerstin / Kiszler, Theresa / Krobot, Pavel / Myagkov, Alexander / Schemann, Vera / Kneifel, Stefan

eISSN: 1866-3516

A comprehensive long-term dataset of remote sensing observations

2023

Abstract: We present a comprehensive quality-controlled 15-month dataset of remote sensing observations of low-level mixed-phase clouds (LLMPCs) taken at the high Arctic site of Ny-Ålesund, Svalbard, Norway. LLMPCs occur frequently in the Arctic region, and ... ...

Abstract	We present a comprehensive quality-controlled 15-month dataset of remote sensing observations of low-level mixed-phase clouds (LLMPCs) taken at the high Arctic site of Ny-Ålesund, Svalbard, Norway. LLMPCs occur frequently in the Arctic region, and extensively affect the energy budget. However, our understanding of the ice microphysical processes taking place in these clouds is incomplete. The dual-wavelength and polarimetric Doppler cloud radar observations, which are the cornerstones of the dataset, provide valuable fingerprints of ice microphysical processes, and the high number of cases included allows for the compiling of robust statistics for process studies. The radar data are complemented with thermodynamic retrievals from a microwave radiometer, liquid base height from a ceilometer and wind fields from large-eddy simulations. All data are quality controlled, especially the cloud radar data, which are accurately calibrated, matched, and corrected for gas and liquid-hydrometeor attenuation, ground clutter and range folding. We finally present an analysis of the temperature dependence of Doppler, dual-wavelength, and polarimetric radar variables, to illustrate how the dataset can be used for cloud microphysical studies. The dataset has been published in Chellini et al. (2023) and is freely available at: www.doi.org/10.5281/zenodo.7803064 .
Subject code	910
Language	English
Publishing date	2023-06-06
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Validation of the Cloud_CCI (Cloud Climate Change Initiative) cloud products in the Arctic

Vinjamuri, Kameswara S. / Vountas, Marco / Lelli, Luca / Stengel, Martin / Shupe, Matthew D. / Ebell, Kerstin / Burrows, John P.

eISSN: 1867-8548

2023

Abstract: The role of clouds in the Arctic radiation budget is not well understood. Ground-based and airborne measurements provide valuable data to test and improve our understanding. However, the ground-based measurements are intrinsically sparse, and the ... ...

Abstract	The role of clouds in the Arctic radiation budget is not well understood. Ground-based and airborne measurements provide valuable data to test and improve our understanding. However, the ground-based measurements are intrinsically sparse, and the airborne observations are snapshots in time and space. Passive remote sensing measurements from satellite sensors offer high spatial coverage and an evolving time series, having lengths potentially of decades. However, detecting clouds by passive satellite remote sensing sensors is challenging over the Arctic because of the brightness of snow and ice in the ultraviolet and visible spectral regions and because of the small brightness temperature contrast to the surface. Consequently, the quality of the resulting cloud data products needs to be assessed quantitatively. In this study, we validate the cloud data products retrieved from the Advanced Very High Resolution Radiometer (AVHRR) post meridiem (PM) data from the polar-orbiting NOAA-19 satellite and compare them with those derived from the ground-based instruments during the sunlit months. The AVHRR cloud data products by the European Space Agency (ESA) Cloud Climate Change Initiative (Cloud_CCI) project uses the observations in the visible and IR bands to determine cloud properties. The ground-based measurements from four high-latitude sites have been selected for this investigation: Hyytiälä (61.84 ∘ N, 24.29 ∘ E), North Slope of Alaska (NSA; 71.32 ∘ N, 156.61 ∘ W), Ny-Ålesund (Ny-Å; 78.92 ∘ N, 11.93 ∘ E), and Summit (72.59 ∘ N, 38.42 ∘ W). The liquid water path (LWP) ground-based data are retrieved from microwave radiometers, while the cloud top height (CTH) has been determined from the integrated lidar–radar measurements. The quality of the satellite products, cloud mask and cloud optical depth (COD), has been assessed using data from NSA, whereas LWP and CTH have been investigated over Hyytiälä, NSA, Ny-Å, and Summit. The Cloud_CCI COD results for liquid water clouds are in better agreement with the NSA ...
Subject code	333
Language	English
Publishing date	2023-06-13
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Validation of the Cloud_CCI cloud products in the Arctic

Vinjamuri, Kameswara S. / Vountas, Marco / Lelli, Luca / Stengel, Martin / Shupe, Matthew D. / Ebell, Kerstin / Burrows, John P.

eISSN: 1867-8548

2023

Abstract	The role of clouds in the Arctic radiation budget is not well understood. Ground-based and airborne measurements provide valuable data to test and improve our understanding. However, the ground-based measurements are intrinsically sparse, and the airborne observations are snapshots in time and space. Passive remote sensing measurements from satellite sensors offer high spatial coverage and an evolving time series, having lengths potentially of decades. However, detecting clouds by passive satellite remote sensing sensors is challenging over the Arctic because of the brightness of snow and ice in the ultraviolet and visible spectral regions, and because of the small brightness temperature contrast to the surface. Consequently, the quality of the resulting cloud data products needs to be assessed quantitatively. In this study, we validate the cloud data products retrieved from the Advanced Very High Resolution Radiometer (AVHRR) post meridiem (PM) data from the polar-orbiting NOAA-19 satellite and compare them with those derived from the ground-based instruments during the sunlit months. The AVHRR cloud data products by the European Space Agency’s (ESA) Cloud Climate Change Initiative (Cloud_CCI) project, which uses the observations in the visible and IR bands to determine cloud properties. The ground-based measurements from four high-latitude sites have been selected for this investigation: Hyytiälä (61.84° N, 24.29° E), North Slope of Alaska (NSA, 71.32° N, 156.61° W), Ny-Ålesund (Ny-Å, 78.92° N, 11.93° E), and Summit (72.59° N, 38.42° W). The Liquid Water Path (LWP) ground-based data are retrieved from microwave radiometers, while the Cloud Top Height (CTH) has been determined from the integrated lidar-radar measurements. The quality of the satellite products, Cloud Mask and Cloud Optical Depth (COD), have been assessed using data from NSA, whereas LWP and CTH have been investigated over Hyytiälä, NSA, Ny-Å, and Summit. The Cloud_CCI COD results for liquid water clouds are in better agreement with the NSA ...
Subject code	551
Language	English
Publishing date	2023-01-30
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: The influence of water vapor anomalies on clouds and their radiative effect at Ny-Ålesund

Nomokonova, Tatiana / Ebell, Kerstin / Löhnert, Ulrich / Maturilli, Marion / Ritter, Christoph

eISSN: 1680-7324

2020

Abstract: The occurrence of events with increased and decreased integrated water vapor (IWV) at the Arctic site Ny-Ålesund, their relation to cloud properties, and the surface cloud radiative effect (CRE) is investigated. For this study, we used almost 2.5 years ( ... ...

Abstract	The occurrence of events with increased and decreased integrated water vapor (IWV) at the Arctic site Ny-Ålesund, their relation to cloud properties, and the surface cloud radiative effect (CRE) is investigated. For this study, we used almost 2.5 years (from June 2016 to October 2018) of ground-based cloud observations processed with the Cloudnet algorithm, IWV from a microwave radiometer (MWR), long-term radiosonde observations, and backward trajectories FLEXTRA. Moist and dry anomalies were found to be associated with North Atlantic flows and air transport within the Arctic region, respectively. The amount of water vapor is often correlated to cloud occurrence, presence of cloud liquid water, and liquid water path (LWP) and ice water path (IWP). In turn, changes in the cloud properties cause differences in surface CRE. During dry anomalies, in autumn, winter, and spring, the mean net surface CRE was lower by 2–37 W m −2 with respect to normal conditions, while in summer the cloud-related surface cooling was reduced by 49 W m −2 . In contrast, under moist conditions in summer the mean net surface CRE becomes more negative by 25 W m −2 , while in other seasons the mean net surface CRE was increased by 5–37 W m −2 . Trends in the occurrence of dry and moist anomalies were analyzed based on a 25-year radiosonde database. Dry anomalies have become less frequent, with rates for different seasons ranging from −12.8 % per decade to −4 % per decade, while the occurrence of moist events has increased at rates from 2.8 % per decade to 6.4 % per decade.
Subject code	333
Language	English
Publishing date	2020-04-30
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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