scholarly journals AMALi – the Airborne Mobile Aerosol Lidar for Arctic research

2010 ◽  
Vol 10 (6) ◽  
pp. 2947-2963 ◽  
Author(s):  
I. S. Stachlewska ◽  
R. Neuber ◽  
A. Lampert ◽  
C. Ritter ◽  
G. Wehrle
Keyword(s):  
Weather Conditions ◽  
The Arctic ◽  
Unknown Boundary ◽  
Polar Regions ◽  
Raman Lidar ◽  
Reliable Operation ◽  
Marine Research ◽  
Cloud Properties ◽  
Iterative Inversion ◽  
532 Nm

Abstract. The Airborne Mobile Aerosol Lidar (AMALi) is an instrument developed at the Alfred Wegener Institute for Polar and Marine Research for reliable operation under the challenging weather conditions at the Earth's polar regions. Since 2003 the AMALi has been successfully deployed for measurements in ground-based installation and zenith- or nadir-pointing airborne configurations during several scientific campaigns in the Arctic. The lidar provides backscatter profiles at two wavelengths (355/532 nm or 1064/532 nm) together with the linear depolarization at 532 nm, from which aerosol and cloud properties can be derived. This paper presents the characteristics and capabilities of the AMALi system and gives examples of its usage for airborne and ground-based operations in the Arctic. As this backscatter lidar normally does not operate in aerosol-free layers special evaluation schemes are discussed, the nadir-pointing iterative inversion for the case of an unknown boundary condition and the two-stream approach for the extinction profile calculation if a second lidar system probes the same air mass. Also an intercomparison of the AMALi system with an established ground-based Koldewey Aerosol Raman Lidar (KARL) is given.

scholarly journals AMALi – the Airborne Mobile Aerosol Lidar for Arctic research

2009 ◽  
Vol 9 (5) ◽  
pp. 18745-18792 ◽  
Author(s):  
I. S. Stachlewska ◽  
R. Neuber ◽  
A. Lampert ◽  
C. Ritter ◽  
G. Wehrle
Keyword(s):  
Present State ◽  
Aerosol Particles ◽  
Weather Conditions ◽  
The Arctic ◽  
Polar Regions ◽  
Marine Research ◽  
The Past ◽  
Cloud Properties ◽  
And Performance

Abstract. The Airborne Mobile Aerosol Lidar (AMALi) is an instrument developed at the Alfred Wegener Institute for Polar and Marine Research for a trouble-free operation under the challenging weather conditions at the Earth's polar regions. Since 2003 the AMALi has been successfully deployed for measurements in the ground-based installation and the zenith- or nadir-aiming airborne configurations during several scientific campaigns in the Arctic. The lidar provides profiles of the total backscatter at two wavelengths, from which aerosol and cloud properties are derived. It measures also the linear depolarization of the backscattered return, allowing for the discrimination of thermodynamic cloud phase and the identification of the presence of non-spherical aerosol particles. This paper presents the capability characteristics and performance of the past and present state of the AMALi system, as well as discusses the ground-based and airborne evaluation schemes applied to invert the data.

scholarly journals Ground-based lidar measurements from Ny-Ålesund during ASTAR 2007

2009 ◽  
Vol 9 (22) ◽  
pp. 9059-9081 ◽  
Author(s):  
A. Hoffmann ◽  
C. Ritter ◽  
M. Stock ◽  
M. Shiobara ◽  
A. Lampert ◽  
...  
Keyword(s):  
Optical Properties ◽  
Weather Conditions ◽  
The Arctic ◽  
Particle Detection ◽  
Marine Research ◽  
Air Mass ◽  
Tropospheric Aerosol ◽  
Ground Based Lidar ◽  
Micro Pulse Lidar ◽  
Mixed Phase Clouds

Abstract. During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) in March and April 2007, measurements obtained at the AWIPEV Arctic Research Base in Ny-Ålesund, Spitsbergen at 78.9° N, 11.9° E (operated by the Alfred Wegener Institute for Polar and Marine Research – AWI and the Institut polaire français Paul-Emile Victor – IPEV), supported the airborne campaign. This included lidar data from the Koldewey Aerosol Raman Lidar (KARL) and the Micro Pulse Lidar (MPL), located in the atmospheric observatory as well as photometer data and the daily launched radiosonde. The MPL features nearly continuous measurements; the KARL was switched on whenever weather conditions allowed observations (145 h in 61 days). From 1 March to 30 April, 71 meteorological balloon soundings were performed and compared with the concurrent MPL measurements; photometer measurements are available from 18 March. For the KARL data, a statistical overview of particle detection based on their optical properties backscatter ratio and volume depolarization can be given. The altitudes of the occurrence of the named features (subvisible and visible ice and water as well as mixed-phase clouds, aerosol layers) as well as their dependence on different air mass origins are analyzed. Although the spring 2007 was characterized by rather clean conditions, diverse case studies of cloud and aerosol occurrence during March and April 2007 are presented in more detail, including temporal development and main optical properties as depolarization, backscatter and extinction coefficients. Links between air mass origins and optical properties can be presumed but need further evidence.

Error Structure and Atmospheric Temperature Trends in Observations from the Microwave Sounding Unit

2009 ◽  
Vol 22 (7) ◽  
pp. 1661-1681 ◽  
Author(s):  
Cheng-Zhi Zou ◽  
Mei Gao ◽  
Mitchell D. Goldberg
Keyword(s):  
Lower Stratosphere ◽  
Weather Conditions ◽  
Atmospheric Temperature ◽  
The Arctic ◽  
Polar Regions ◽  
Climate Trends ◽  
Orbital Geometry ◽  
Microwave Sounding Unit ◽  
Order Of Magnitude ◽  
Microwave Sounding

Abstract The Microwave Sounding Unit (MSU) onboard the National Oceanic and Atmospheric Administration polar-orbiting satellites measures the atmospheric temperature from the surface to the lower stratosphere under all weather conditions, excluding precipitation. Although designed primarily for monitoring weather processes, the MSU observations have been extensively used for detecting climate trends, and calibration errors are a major source of uncertainty. To reduce this uncertainty, an intercalibration method based on the simultaneous nadir overpass (SNO) matchups for the MSU instruments on satellites NOAA-10, -11, -12, and -14 was developed. Due to orbital geometry, the SNO matchups are confined to the polar regions, where the brightness temperature range is slightly smaller than the global range. Nevertheless, the resulting calibration coefficients are applied globally to the entire life cycle of an MSU satellite. Such intercalibration reduces intersatellite biases by an order of magnitude compared to prelaunch calibration and, thus, results in well-merged time series for the MSU channels 2, 3, and 4, which respectively represent the deep layer temperature of the midtroposphere (T2), tropopause (T3), and lower stratosphere (T4). Focusing on the global atmosphere over ocean surfaces, trends for the SNO-calibrated T2, T3, and T4 are, respectively, 0.21 ± 0.07, 0.08 ± 0.08, and −0.38 ± 0.27 K decade−1 from 1987 to 2006. These trends are independent of the number of limb-corrected footprints used in the dataset, and trend differences are marginal for varying bias correction techniques for merging the overlapping satellites on top of the SNO calibration. The spatial pattern of the trends reveals the tropical midtroposphere to have warmed at a rate of 0.28 ± 0.19 K decade−1, while the Arctic atmosphere warmed 2 to 3 times faster than the global average. The troposphere and lower stratosphere, however, cooled across the southern Indian and Atlantic Oceans adjacent to the Antarctic continent. To remove the stratospheric cooling effect in T2, channel trends from T2 and T3 (T23) and T2 and T4 (T24) were combined. The trend patterns for T23 and T24 are in close agreement, suggesting internal consistencies for the trend patterns of the three channels.

scholarly journals Multi-wavelength Raman lidar observations of the Eyjafjallajökull volcanic cloud over Potenza, southern Italy

2012 ◽  
Vol 12 (4) ◽  
pp. 2229-2244 ◽  
Author(s):  
L. Mona ◽  
A. Amodeo ◽  
G. D'Amico ◽  
A. Giunta ◽  
F. Madonna ◽  
...  
Keyword(s):  
Weather Conditions ◽  
Saharan Dust ◽  
Volcanic Aerosol ◽  
Raman Lidar ◽  
Angstrom Exponent ◽  
Lidar Measurements ◽  
Ångström Exponent ◽  
Multi Wavelength ◽  
532 Nm ◽  
Ångstrom Exponent

Abstract. During the eruption of Eyjafjallajökull in April–May 2010 multi-wavelength Raman lidar measurements were performed at the CNR-IMAA Atmospheric Observatory (CIAO), whenever weather conditions permitted observations. A methodology both for volcanic layer identification and accurate aerosol typing has been developed. This methodology relies on the multi-wavelength Raman lidar measurements and the support of long-term lidar measurements performed at CIAO since 2000. The aerosol mask for lidar measurements performed at CIAO during the 2010 Eyjafjallajökull eruption has been obtained. Volcanic aerosol layers were observed in different periods: 19–22 April, 27–29 April, 8–9 May, 13–14 May and 18–19 May. A maximum aerosol optical depth of about 0.12–0.13 was observed on 20 April, 22:00 UTC and 13 May, 20:30 UTC. Volcanic particles were detected at low altitudes, in the free troposphere and in the upper troposphere. Occurrences of volcanic particles within the PBL were detected on 21–22 April and 13 May. A Saharan dust event was observed on 13–14 May: dust and volcanic particles were simultaneously detected at CIAO at separated different altitudes as well as mixed within the same layer. Lidar ratios at 355 and 532 nm, the Ångström exponent at 355/532 nm, the backscatter-related Ångström exponent at 532/1064 nm and the particle linear depolarization ratio at 532 nm measured inside the detected volcanic layers are discussed. The dependence of these quantities on relative humidity has been investigated by using co-located microwave profiler measurements. The measured values of these intensive parameters indicate the presence of volcanic sulfates/continental mixed aerosol in the volcanic aerosol layers observed at CIAO. In correspondence of the maxima observed in the volcanic aerosol load on 19–20 April and 13 May, different values of intensive parameters were observed. Apart from the occurrence of sulfate aerosol, these values indicate also the presence of some ash which is affected by the aging during transport over Europe.

scholarly journals Polar Stratospheric Cloud Observations in the 2006/07 Arctic Winter by Using an Improved Micropulse Lidar

2009 ◽  
Vol 26 (10) ◽  
pp. 2136-2148 ◽  
Author(s):  
Carmen Cordoba-Jabonero ◽  
Manuel Gil ◽  
Margarita Yela ◽  
Marion Maturilli ◽  
Roland Neuber
Keyword(s):  
The Arctic ◽  
Polar Regions ◽  
Full Time ◽  
Raman Lidar ◽  
International Polar Year ◽  
Polar Stratospheric Cloud ◽  
International Polar ◽  
Lidar Observations ◽  
Type Classification

Abstract The potential of a new improved version of micropulse lidar (MPL-4) on polar stratospheric cloud (PSC) detection is evaluated in the Arctic over Ny-Ålesund (79°N, 12°E), Norway. The campaign took place from January to February 2007 in the frame of the International Polar Year (IPY) activities. Collocated Alfred Wegener Institute (AWI) Koldewey Aerosol Raman Lidar (KARL) devoted to long-term Arctic PSC monitoring is used for validation purposes. PSC detection is based on lidar retrievals of both backscattering ratio R and volume depolarization ratio δV. Two episodes were unequivocally attributed to PSCs: 21–22 January and 5–6 February 2007, showing a good correlation between MPL-4 and KARL backscattering ratio datasets (mean correlation coefficient = 0.92 ± 0.03). PSC layered structures were characterized for four observational periods coincident with KARL measurements. Also, PSC type classification was determined depending on the retrieved R and δV values as compared with those obtained by KARL long-term Arctic PSC measurements. Tropospheric cloud cover from lidar observations and both ECMWF potential vorticity and temperature at 475 K, in addition to temperature profiles from AWI daily radiosoundings, are also reported. Height-resolved and temporal evolution of both PSC episodes obtained from MPL-4 measurements clearly show that MPL-4 is a suitable instrument to provide long-term PSC statistic monitoring in polar regions. These results are the first reported on PSC detection in the Arctic by using a low-energy and highly pulsed lidar operating on autonomous and full-time continuous mode MPL-4.

DYAMOND-II simulations with IFS-FESOM2

2021 ◽  
Author(s):  
Thomas Rackow ◽  
Nils Wedi ◽  
Kristian Mogensen ◽  
Peter Dueben ◽  
Helge F. Goessling ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ocean Circulation ◽  
Climate Model ◽  
Global Climate Model ◽  
The Arctic ◽  
Global Ocean ◽  
Polar Regions ◽  
Marine Research ◽  
Curvilinear Grid ◽  
The Impact

<p>This presentation will give an overview about an ongoing collaboration between the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). Our recent development is a single-executable coupled configuration of the Integrated Forecasting System (IFS) and the Finite Volume Sea Ice-Ocean Model, FESOM2. This configuration is set up to participate in the DYAMOND project alongside ECMWF’s default IFS-NEMO configuration. IFS-FESOM2 and IFS-NEMO are tentative models to generate “Digital Twin” storm-scale, coupled simulations as envisioned in the European Destination Earth (DestinE) and Next Generation Earth Modelling Systems (NextGEMS) projects.</p><p>FESOM2 has a novel dynamical core that supports multi-resolution triangular grids. The model and its predecessor FESOM1 have been used in many studies over the last decade, with a focus on the role of the polar regions in global ocean circulation. The impact of eddy-permitting and locally eddy-resolving resolution has been addressed in CMIP6 and HighResMIP simulations as part of the AWI-CM-1-1 global climate model, while simulations with up to 1km resolution in the Arctic Ocean have been performed in stand-alone mode.</p><p>Initially, two coupled IFS-FESOM2 configurations have been tested: A coarse-resolution setup with a nominal 1° ocean, and a DYAMOND-II configuration with 0.25° ocean and IFS at 4.5km global resolution on average. For the latter configuration, FESOM2 is mimicking the “ORCA025” tri-polar curvilinear grid of the NEMO model, whose grid boxes have been split into triangles. Initialisation is from ECMWF’s analysis for IFS and NEMO, and from an ERA5-forced ocean spin-up for FESOM2. We discuss technical challenges with respect to the hybrid OpenMP and MPI parallelization in a single-executable context, describe a novel strategy for resource-efficient writing of model output, and summarise future applications such as exploring the impact of flexible FESOM2 grid configurations on the atmosphere - with ocean simulations that resolve leads in sea ice and ocean eddies almost everywhere.</p>

scholarly journals Ground-based lidar measurements from Ny-Ålesund during ASTAR 2007: a statistical overview

2009 ◽  
Vol 9 (4) ◽  
pp. 15453-15510 ◽  
Author(s):  
A. Hoffmann ◽  
C. Ritter ◽  
M. Stock ◽  
M. Shiobara ◽  
A. Lampert ◽  
...  
Keyword(s):  
Optical Properties ◽  
Weather Conditions ◽  
The Arctic ◽  
Research Station ◽  
Marine Research ◽  
Air Mass ◽  
Tropospheric Aerosol ◽  
Ground Based Lidar ◽  
Micro Pulse Lidar ◽  
Mixed Phase Clouds

Abstract. During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) in March and April 2007, measurements obtained at the AWIPEV Research station in Ny-Ålesund, Spitsbergen (operated by the Alfred-Wegener-Institute for Polar and Marine Research and the Institut polaire français Paul-Emile Victor), supported the airborne campaign. This included Lidar data from the Koldewey Aerosol Raman Lidar (KARL) and the Micro Pulse Lidar (MPL), located in the atmospheric observatory as well as photometer data and the daily launched radiosonde. The MPL features nearly continuous measurements; the KARL was switched on whenever weather conditions allowed observations (145 h in 61 days). From 1 March to 30 April, 71 meteorological balloon soundings were performed and compared with the corresponding MPL measurements; photometer measurements are available from 18 March. For the KARL data, a statistical overview based on the optical properties backscatter ratio and volume depolarization can be given. The altitudes of the occurrence of the named features (subvisible and visible ice and water as well as mixed-phase clouds, aerosol layers) as well as their dependence on different air mass origins are analyzed. Although the spring 2007 was characterized by rather clean conditions, diverse case studies of cloud and aerosol occurrence during March and April 2007 are presented in more detail, including temporal development and main optical properties as backscatter, depolarization and extinction coefficients. Links between air mass origins and optical properties can be presumed but need further evidence.

scholarly journals Toward autonomous surface-based infrared remote sensing of polar clouds: retrievals of cloud optical and microphysical properties

2019 ◽  
Vol 12 (9) ◽  
pp. 5071-5086 ◽  
Author(s):  
Penny M. Rowe ◽  
Christopher J. Cox ◽  
Steven Neshyba ◽  
Von P. Walden
Keyword(s):  
Climate Model ◽  
Effective Radius ◽  
The Arctic ◽  
Polar Regions ◽  
Cloud Property ◽  
Microphysical Properties ◽  
Cloud Properties ◽  
Instrument Resolution ◽  
Mean Square Errors ◽  
Ice Fraction

Abstract. Improvements to climate model results in polar regions require improved knowledge of cloud properties. Surface-based infrared (IR) radiance spectrometers have been used to retrieve cloud properties in polar regions, but measurements are sparse. Reductions in cost and power requirements to allow more widespread measurements could be aided by reducing instrument resolution. Here we explore the effects of errors and instrument resolution on cloud property retrievals from downwelling IR radiances for resolutions of 0.1 to 20 cm−1. Retrievals are tested on 336 radiance simulations characteristic of the Arctic, including mixed-phase, vertically inhomogeneous, and liquid-topped clouds and a variety of ice habits. Retrieval accuracy is found to be unaffected by resolution from 0.1 to 4 cm−1, after which it decreases slightly. When cloud heights are retrieved, errors in retrieved cloud optical depth (COD) and ice fraction are considerably smaller for clouds with bases below 2 km than for higher clouds. For example, at a resolution of 4 cm−1, with errors imposed (noise and radiation bias of 0.2 mW/(m2 sr cm−1) and biases in temperature of 0.2 K and in water vapor of −3 %), using retrieved cloud heights, root-mean-square errors decrease from 1.1 to 0.15 for COD, 0.3 to 0.18 for ice fraction (fice), and 10 to 7 µm for ice effective radius (errors remain at 2 µm for liquid effective radius). These results indicate that a moderately low-resolution, surface-based IR spectrometer could provide cloud property retrievals with accuracy comparable to existing higher-resolution instruments and that such an instrument would be particularly useful for low-level clouds.

scholarly journals Enhanced Viral Activity in the Surface Microlayer of the Arctic and Antarctic Oceans

2021 ◽  
Vol 9 (2) ◽  
pp. 317
Author(s):  
Dolors Vaqué ◽  
Julia A. Boras ◽  
Jesús Maria Arrieta ◽  
Susana Agustí ◽  
Carlos M. Duarte ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Food Web ◽  
Physicochemical Characteristics ◽  
The Arctic ◽  
Microbial Food Web ◽  
Surface Microlayer ◽  
Polar Regions ◽  
Nutrient Inputs ◽  
Viral Activity ◽  
The Impact

The ocean surface microlayer (SML), with physicochemical characteristics different from those of subsurface waters (SSW), results in dense and active viral and microbial communities that may favor virus–host interactions. Conversely, wind speed and/or UV radiation could adversely affect virus infection. Furthermore, in polar regions, organic and inorganic nutrient inputs from melting ice may increase microbial activity in the SML. Since the role of viruses in the microbial food web of the SML is poorly understood in polar oceans, we aimed to study the impact of viruses on prokaryotic communities in the SML and in the SSW in Arctic and Antarctic waters. We hypothesized that a higher viral activity in the SML than in the SSW in both polar systems would be observed. We measured viral and prokaryote abundances, virus-mediated mortality on prokaryotes, heterotrophic and phototrophic nanoflagellate abundance, and environmental factors. In both polar zones, we found small differences in environmental factors between the SML and the SSW. In contrast, despite the adverse effect of wind, viral and prokaryote abundances and virus-mediated mortality on prokaryotes were higher in the SML than in the SSW. As a consequence, the higher carbon flux released by lysed cells in the SML than in the SSW would increase the pool of dissolved organic carbon (DOC) and be rapidly used by other prokaryotes to grow (the viral shunt). Thus, our results suggest that viral activity greatly contributes to the functioning of the microbial food web in the SML, which could influence the biogeochemical cycles of the water column.

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