Exploring the representation of clouds and humidity in the Arctic with cloud-resolving simulations using ICON-LEM

2021 ◽  
Author(s):  
Theresa Kiszler ◽  
Giovanni Chellini ◽  
Kerstin Ebell ◽  
Stefan Kneifel ◽  
Vera Schemann
Keyword(s):  
Microwave Radiometer ◽  
Remote Sensing Data ◽  
Large Data ◽  
Research Unit ◽  
Rain Gauge ◽  
The Arctic ◽  
Arctic Amplification ◽  
Data Set ◽  
Microphysical Processes ◽  
Mixed Phase Clouds

<p>The discussions around Arctic Amplification have led to extensive research, as done in the transregional collaboration (AC)³. One focus are the feedback mechanisms that are strengthening or weakening the warming. Several of these feedbacks involve moisture in the atmosphere in all phases. To understand these better we have been running and analysing daily cloud-resolving simulations. We performed these simulations for a region more strongly affected by the warming around Ny-Ålesund (Svalbard), which is challenging due to its diverse surface properties and mountainous surrounding. We have created an outstandingly large data set of several months of these simulations with 600 m resolution, using the Icosahedral non-hydrostatic model in the large-eddy mode (ICON-LEM).</p> <p>To gain some understanding of how well the model can represent such a complex location, we evaluated the performance of the model. For this, we used a range of observations from the measurement super-site located at Ny-Ålesund. This included radiosondes [1], a rain gauge, a microwave radiometer and further processed remote sensing data. Combining the measurements and simulations enables us to provide thorough statistics for different variables connected to clouds and to establish an understanding of how well they are represented.</p> <p>We show that the model is capable of simulating the two distinct flow regimes in the boundary layer and the free troposphere. Further, we found a tendency in the model to misrepresent liquid and mixed-phase clouds as purely ice clouds. Though the water vapour is well captured, we found further steps in the chain towards precipitation formation are insufficiently represented. Through the use of forward simulations and expanded model output, we can continue to get a better picture of possibilities to understand and improve the microphysical processes.</p> <p><em>This work was supported by the</em><em> DFG funded Transregio-project TR 172 “Arctic Amplification </em>(AC)3<em>“.</em></p> <p><strong>References</strong></p> <p>[1] M. Maturilli, High resolution radiosonde measurements from station Ny-Ålesund (2017-04 et seq). <em>Alfred</em> <em>Wegener Institute - Research Unit Potsdam, PANGAEA</em>, https://doi.org/10.1594/PANGAEA.914973 (2020)</p>

scholarly journals PHIPS-HALO: the airborne Particle Habit Imaging and Polar Scattering probe – Part 3: Single-particle phase discrimination and particle size distribution based on the angular-scattering function

2021 ◽  
Vol 14 (4) ◽  
pp. 3049-3070
Author(s):  
Fritz Waitz ◽  
Martin Schnaiter ◽  
Thomas Leisner ◽  
Emma Järvinen
Keyword(s):  
Particle Size ◽  
Single Particle ◽  
Large Data ◽  
The Arctic ◽  
Scattering Data ◽  
Scattering Function ◽  
Data Set ◽  
Phase Discrimination ◽  
Angular Scattering

Abstract. A major challenge for in situ observations in mixed-phase clouds remains the phase discrimination and sizing of cloud hydrometeors. In this work, we present a new method for determining the phase of individual cloud hydrometeors based on their angular-light-scattering behavior employed by the PHIPS (Particle Habit Imaging and Polar Scattering) airborne cloud probe. The phase discrimination algorithm is based on the difference of distinct features in the angular-scattering function of spherical and aspherical particles. The algorithm is calibrated and evaluated using a large data set gathered during two in situ aircraft campaigns in the Arctic and Southern Ocean. Comparison of the algorithm with manually classified particles showed that we can confidently discriminate between spherical and aspherical particles with a 98 % accuracy. Furthermore, we present a method for deriving particle size distributions based on single-particle angular-scattering data for particles in a size range from 100 µm ≤ D ≤ 700 µm and 20 µm ≤ D ≤ 700 µm for droplets and ice particles, respectively. The functionality of these methods is demonstrated in three representative case studies.

scholarly journals Seasonal and interannual variations in the propagation of photosynthetically available radiation through the Arctic atmosphere

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
J. Laliberté ◽  
S. Bélanger ◽  
M. Babin
Keyword(s):  
Large Data ◽  
The Arctic ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
The Sun ◽  
Photosynthetically Available Radiation ◽  
Data Set ◽  
Melt Ponds ◽  
Arctic Atmosphere ◽  
Marine Productivity

The Arctic atmosphere–surface system transmits visible light from the Sun to the ocean, determining the annual cycle of light available to microalgae. This light is referred to as photosynthetically available radiation (PAR). A known consequence of Arctic warming is the change at the atmosphere–ocean interface (longer ice-free season, younger ice), implying an increase in the percentage of PAR being transferred to the water. However, much less is known about the recent changes in how much PAR is being transferred by the overlaying atmosphere. We studied the transfer of PAR through the atmosphere between May 21 and July 23 at a pan-Arctic scale for the period ranging from 2000 to 2016. By combining a large data set of atmospheric and surface conditions into a radiative transfer model, we computed the percentage of PAR transferred to the surface. We found that typical Arctic atmospheres convey between 60% and 70% of the incident PAR received from the Sun, meaning the Arctic atmosphere typically transmits more light than most sea ice surfaces, with the exception of mature melt ponds. We also found that the transfer of PAR through the atmosphere decreased at a rate of 2.3% per decade over the studied period, due to the increase in cloudiness and the weaker radiative interaction between the atmosphere and the surface. Further investigation is required to address how, in the warmer Arctic climate, this negative trend would compensate for the increased surface transmittance and its consequences on marine productivity.

Microphysical cloud parameters of optically thin clouds in the Arctic in summer 2017

2020 ◽  
Author(s):  
Philipp Richter ◽  
Mathias Palm ◽  
Christine Weinzierl ◽  
Penny Rowe ◽  
Justus Notholt
Keyword(s):  
Aerosol Particles ◽  
Microwave Radiometer ◽  
Arctic Region ◽  
Open Water ◽  
The Arctic ◽  
Arctic Amplification ◽  
Cloud Parameters ◽  
Microphysical Properties ◽  
Infrared Spectrometer

<p>As a precursor of the current MOSAiC campaign, the PASCAL campaign took place in summer 2017 around Svalbard [1]. In the scope of the project (AC)3, infrared radiation emitted by clouds was measured using a calibrated Fourier Transform Infrared Spectrometer (EM-FTIR). EM-FTIR can be used for different purposes, like the observation of trace gases or microphysical cloud parameters (MCP) like cloud optical depths and cloud effective droplet radii. In the observation of MCP, EM-FTIR can be used to measure optically thin clouds with very low amounts of liquid water paths below 30 gm-2, where microwave radiometer face problems because of their larger measuring uncertainty. </p><p>The retrieval of the MCP is performed using the newly introduced retrieval code CLARRA [2]. CLARRA shows a high accuracy in the retrieval of MCP from low-level clouds, which were often observed during the measurements. </p><p>The measurements were performed between June 2017 and August 2017 around Svalbard and include measurements of clouds over sea ice and open water. The spatial distribution of the MCP around Svalbard and a comparison to model results will be shown. This dataset can later serve as a reference for the question, how representative the measurements in Ny-Alesund on Spitzbergen are for the nearby arctic region.</p><p>[1] Wendisch et al., 2019: The Arctic Cloud Puzzle: Using ACLOUD/PASCAL Multi-Platform Observations to Unravel the Role of Clouds and Aerosol Particles in Arctic Amplification, Bull. Amer. Meteor. Soc., 100 (5), 841–871, doi:10.1175/BAMS-D-18-0072.1<br>[2] Rowe et al., 2019: Toward autonomous surface-based infrared remote sensing of polar clouds: retrievals of cloud optical and microphysical properties, Atmos. Meas. Tech., 12, 5071–5086, https://doi.org/10.5194/amt-12-5071-2019</p>

scholarly journals Validation of middle atmospheric campaign-based water vapour measured by the ground-based microwave radiometer MIAWARA-C

2013 ◽  
Vol 6 (1) ◽  
pp. 1311-1359 ◽  
Author(s):  
B. Tschanz ◽  
C. Straub ◽  
D. Scheiben ◽  
K. A. Walker ◽  
G. P. Stiller ◽  
...  
Keyword(s):  
Water Vapour ◽  
Random Error ◽  
Microwave Radiometer ◽  
Incident Radiation ◽  
Temporal Variations ◽  
The Arctic ◽  
Atmospheric Water ◽  
Data Set ◽  
Atmospheric Water Vapour ◽  
Measurement Campaigns

Abstract. Middle atmospheric water vapour can be used as a tracer for dynamical processes. It is mainly measured by satellite instruments and ground-based microwave radiometers. Ground-based instruments capable of measuring middle atmospheric water vapour are sparse but valuable as they complement satellite measurements, are relatively easy to maintain and have a long lifetime. MIAWARA-C is a ground-based microwave radiometer for middle atmospheric water vapour designed for use on measurement campaigns for both atmospheric case studies and instrument intercomparisons. MIAWARA-C's retrieval version 1.1 (v1.1) is set up in a way to provide a consistent data set even if the instrument is operated from different locations on a campaign basis. The sensitive altitude range for v1.1 extends from 4 hPa (37 km) to 0.017 hPa (75 km). MIAWARA-C measures two polarisations of the incident radiation in separate receiver channels and can therefore provide two independent measurements of the same air mass. The standard deviation of the difference between the profiles obtained from the two polarisations is in excellent agreement with the estimated random error of v1.1. In this paper, the quality of v1.1 data is assessed during two measurement campaigns: (1) five months of measurements in the Arctic (Sodankylä, 67.37° N/26.63° E) and (2) nine months of measurements at mid-latitudes (Zimmerwald, 46.88° N/7.46° E). For both campaigns MIAWARA-C's profiles are compared to measurements from the satellite experiments Aura MLS and MIPAS. In addition, comparisons to ACE-FTS and SOFIE are presented for the Arctic and to the ground-based radiometer MIAWARA for the mid-latitudinal campaign. In general all intercomparisons show high correlation coefficients, above 0.5 at altitudes above 45 km, confirming the ability of MIAWARA-C to monitor temporal variations on the order of days. The biases are generally below 10% and within the estimated systematic uncertainty of MIAWARA-C. No consistent wet or dry bias is identified for MIAWARA-C. In addition, comparisons to the reference instruments indicate the estimated random error of v1.1 to be a realistic measure of the random variation on the retrieved profile.

scholarly journals Statistics on clouds and their relation to thermodynamic conditions at Ny-Ålesund using ground-based sensor synergy

2019 ◽  
Vol 19 (6) ◽  
pp. 4105-4126 ◽  
Author(s):  
Tatiana Nomokonova ◽  
Kerstin Ebell ◽  
Ulrich Löhnert ◽  
Marion Maturilli ◽  
Christoph Ritter ◽  
...  
Keyword(s):  
Microwave Radiometer ◽  
Single Layer ◽  
Mixed Phase ◽  
The Arctic ◽  
Time Data ◽  
Liquid Water Path ◽  
Marine Research ◽  
Mean Values ◽  
Water Path ◽  
Mixed Phase Clouds

Abstract. The French–German Arctic research base AWIPEV (the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research – AWI – and the French Polar Institute Paul Emile Victor – PEV) at Ny-Ålesund, Svalbard, is a unique station for monitoring cloud-related processes in the Arctic. For the first time, data from a set of ground-based instruments at the AWIPEV observatory are analyzed to characterize the vertical structure of clouds. For this study, a 14-month dataset from Cloudnet combining observations from a ceilometer, a 94 GHz cloud radar, and a microwave radiometer is used. A total cloud occurrence of ∼81 %, with 44.8 % multilayer and 36 % single-layer clouds, was found. Among single-layer clouds the occurrence of liquid, ice, and mixed-phase clouds was 6.4 %, 9 %, and 20.6 %, respectively. It was found that more than 90 % of single-layer liquid and mixed-phase clouds have liquid water path (LWP) values lower than 100 and 200 g m−2, respectively. Mean values of ice water path (IWP) for ice and mixed-phase clouds were found to be 273 and 164 g m−2, respectively. The different types of single-layer clouds are also related to in-cloud temperature and the relative humidity under which they occur. Statistics based on observations are compared to ICOsahedral Non-hydrostatic (ICON) model output. Distinct differences in liquid-phase occurrence in observations and the model at different environmental temperatures lead to higher occurrence of pure ice clouds. A lower occurrence of mixed-phase clouds in the model at temperatures between −20 and −5 ∘C becomes evident. The analyzed dataset is useful for satellite validation and model evaluation.

scholarly journals Secondary ice production in NorESM2 climate model: quantifying the impact on Arctic clouds

2021 ◽  
Author(s):  
Georgia Sotiropoulou ◽  
Anna Lewinschal ◽  
Annica Ekman ◽  
Athanasios Nenes
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
The Arctic ◽  
Liquid Water Path ◽  
Arctic Clouds ◽  
Radiative Balance ◽  
Microphysical Processes ◽  
Ice Production ◽  
Mixed Phase Clouds ◽  
The Impact

<p>Arctic clouds are among the largest sources of uncertainty in predictions of Arctic weather and climate. This is mainly due to errors in the representation of the cloud thermodynamic phase and the associated radiative impacts, which largely depends on the parameterization of cloud microphysical processes. Secondary ice processes (SIP) are among the microphysical processes that are poorly represented, or completely absent, in climate models. In most models, including the Norwegian Earth System Model -version 2 (NorESM2), Hallet-Mossop (H-M) is the only SIP mechanism available. In this study we further improve the description of H-M and include two additional SIP mechanisms (collisional break-up and drop-shattering) in NorESM2. Our results indicate that these additions improve the agreement between observed and modeled ice crystal number concentrations and liquid water path in mixed-phase clouds observed at Ny-Alesund in 2016-2017. We then conclude by quantifying the impact of these overlooked SIP mechanisms for cloud microphysical characteristics, properties and the radiative balance throughout the Arctic.</p><p> </p>

scholarly journals Snowmelt onset over Arctic sea ice from passive microwave satellite data: 1979–2012

2014 ◽  
Vol 8 (6) ◽  
pp. 2089-2100 ◽  
Author(s):  
A. C. Bliss ◽  
M. R. Anderson
Keyword(s):  
Sea Ice ◽  
Microwave Radiometer ◽  
Arctic Region ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Data Set ◽  
Brightness Temperatures ◽  
Arctic Sea ◽  
Microwave Imager ◽  
The Arctic Region

Abstract. An updated version (Version 3) of the Snow Melt Onset Over Arctic Sea Ice from SMMR (Scanning Multichannel Microwave Radiometer) and SSM/I-SSMIS (Special Sensor Microwave/Imager-Special Sensor Microwave Imager/Sounder) Brightness Temperatures data set is now available. The data record has been reprocessed and extended to cover the years 1979–2012. From this data set, a statistical summary of melt onset (MO) dates on Arctic sea ice is presented. The mean MO date for the Arctic Region is 13 May (132.5 DOY – day of year) with a standard deviation of ±7.3 days. Regionally, mean MO dates vary from 15 March (73.2 DOY) in the St. Lawrence Gulf to 10 June (160.9 DOY) in the Central Arctic. Statistically significant decadal trends indicate that MO is occurring 6.6 days decade−1 earlier in the year for the Arctic Region. Regionally, MO trends are as great as −11.8 days decade−1 in the East Siberian Sea. The Bering Sea is an outlier and MO is occurring 3.1 days decade−1 later in the year.

scholarly journals Statistics on clouds and their relation to thermodynamic conditions at Ny-Ålesund using ground-based sensor synergy

2018 ◽  
Author(s):  
Tatiana Nomokonova ◽  
Kerstin Ebell ◽  
Ulrich Löhnert ◽  
Marion Maturilli ◽  
Christoph Ritter ◽  
...  
Keyword(s):  
Microwave Radiometer ◽  
Single Layer ◽  
Mixed Phase ◽  
The Arctic ◽  
Time Data ◽  
Ice Clouds ◽  
Mean Values ◽  
Cloud Temperature ◽  
Thermodynamic Conditions ◽  
Mixed Phase Clouds

Abstract. The French–German Arctic Research Base AWIPEV at Ny-Ålesund, Svalbard, is an unique station for monitoring cloud related processes in the Arctic. For the first time, data from a set of ground-based instruments at AWIPEV observatory are analyzed to characterize the vertical structure of clouds. For this study, a 14-month dataset from Cloudnet combining observations from a ceilometer, a 94 GHz cloud radar and a microwave radiometer, is used. The total cloud occurrence of 81 %, with 44.8 % of multi-layer and 36 % of single-layer clouds was found. Among single-layer clouds the occurrence of liquid, ice and mixed-phase clouds was 6.4 %, 9 % and 20.6 %, respectively. It was found, that more than 90 % of single-layer liquid and mixed-phase clouds have LWP values lower than 100 and 200 g m2, respectively. Mean values of IWP for ice and mixed-phase clouds were found to be 273 and 164 g m2, respectively. The different types of single-layer clouds are also related to in-cloud temperature and relative humidity under which they occur. Statistics based on observations are compared to the ICON model output. Distinct differences in liquid phase occurrence in observations and the model at different environmental temperatures leading to higher occurrence of pure ice clouds and lower occurrence of mixed-phase clouds in the model at temperatures between −20° and −5 °C become evident. The analyzed dataset is useful for satellite validation and model evaluation.

scholarly journals PHIPS-HALO: the airborne particle habit imaging and polar scattering probe – Part 3: Single Particle Phase Discrimination and Particle Size Distribution based on Angular Scattering Function

2020 ◽  
Author(s):  
Fritz Waitz ◽  
Martin Schnaiter ◽  
Thomas Leisner ◽  
Emma Järvinen
Keyword(s):  
Particle Size ◽  
Single Particle ◽  
Large Data ◽  
The Arctic ◽  
Scattering Data ◽  
Scattering Function ◽  
Data Set ◽  
Phase Discrimination ◽  
Angular Scattering

Abstract. A major challenge for for in-situ observations in mixed phase clouds remains the phase discrimination and sizing of cloud hydrometeors. In this work, we present a new method to determine the phase of individual cloud hydrometeors based on their angular light scattering behaviour employed by the PHIPS airborne cloud probe. The phase discrimination algorithm is based on the difference of distinct features in the angular scattering function of spherical and aspherical particles. The algorithm is calibrated and validated using a large data set gathered during two in-situ aircraft campaigns in the Arctic and outhern Ocean. Comparison of the algorithm with manually classified particles showed that we can confidently discriminate between spherical and aspherical particles with a 98 % accuracy. Furthermore, we present a method to derive particle size distributions based on single particle angular scattering data for particles in a size range from 100 μm 

scholarly journals Simulation of mixed-phase clouds with the ICON-LEM in the complex Arctic environment around Ny-Ålesund

2019 ◽  
Author(s):  
Vera Schemann ◽  
Kerstin Ebell
Keyword(s):  
High Resolution ◽  
General Structure ◽  
Microwave Radiometer ◽  
Value Added ◽  
Mixed Phase ◽  
The Arctic ◽  
Radiative Energy ◽  
Liquid Water Path ◽  
Substantial Impact ◽  
Mixed Phase Clouds

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.

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