Measurements of precipitation in Dumont d'Urville, Terre Adélie, East Antarctica

Abstract. The first results of a campaign of intensive observation of precipitation in Dumont d'Urville, Antarctica, are presented. Several instruments collected data from October 2015, including a polarimetric weather radar (MXPol), a Micro Rain Radar (MRR), a weighing gauge (Pluvio2), and a Multi-Angle Snowflake Camera (MASC). These instruments collected the first model-free measurements of precipitation in the region in the region of Terre Adélie (Adélie Land), including of precipitation microphysics. Microphysical observations during the austral summer 2015/2016 showed that, close to ground level, aggregates are the dominant hydrometeor type, together with small ice particles (mostly originating from blowing snow), and that riming often occurs. Contamination of the Pluvio2 measurements in windy conditions is observed and partly removed through synergistic use of MRR data. The yearly accumulated precipitation of snow (300 m above ground), obtained by means of a local conversion relation of MRR data, trained on the Pluvio2 measurement of the summer period, is estimated to be 815 mm of water equivalent, with a confidence interval ranging between 739.5 to 989 mm. Climatological data obtained from satellite-borne radars, and the ERA-Interim reanalysis of the European Center for Medium-Range Weather Forecasts (ECMWF) both provide lower yearly totals: 655 mm for ERA-Interim, while 679 mm for the climatological data over DDU. ERA-Interim seems to overestimate the occurrence of low-intensity precipitation events especially in summer, while visual observations conducted at the research stations all year long seem to underestimate it. Overall, this manuscript provides insightful examples of the added values of precipitation monitoring in Antarctica with a synergistic use of in-situ and remote sensing measurements.

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Measurements of precipitation in Dumont d'Urville, Adélie Land, East Antarctica

The Cryosphere ◽

10.5194/tc-11-1797-2017 ◽

2017 ◽

Vol 11 (4) ◽

pp. 1797-1811 ◽

Cited By ~ 28

Author(s):

Jacopo Grazioli ◽

Christophe Genthon ◽

Brice Boudevillain ◽

Claudio Duran-Alarcon ◽

Massimo Del Guasta ◽

...

Keyword(s):

Austral Summer ◽

Ground Level ◽

Blowing Snow ◽

Climatological Data ◽

Weather Forecasts ◽

First Results ◽

Terre Adélie ◽

Intensive Observation ◽

Rain Radar

Abstract. The first results of a campaign of intensive observation of precipitation in Dumont d'Urville, Antarctica, are presented. Several instruments collected data from November 2015 to February 2016 or longer, including a polarimetric radar (MXPol), a Micro Rain Radar (MRR), a weighing gauge (Pluvio2), and a Multi-Angle Snowflake Camera (MASC). These instruments collected the first ground-based measurements of precipitation in the region of Adélie Land (Terre Adélie), including precipitation microphysics. Microphysical observations during the austral summer 2015/2016 showed that, close to the ground level, aggregates are the dominant hydrometeor type, together with small ice particles (mostly originating from blowing snow), and that riming is a recurring process. Eleven percent of the measured particles were fully developed graupel, and aggregates had a mean riming degree of about 30 %. Spurious precipitation in the Pluvio2 measurements in windy conditions, leading to phantom accumulations, is observed and partly removed through synergistic use of MRR data. The yearly accumulated precipitation of snow (300 m above ground), obtained by means of a local conversion relation of MRR data, trained on the Pluvio2 measurement of the summer period, is estimated to be 815 mm of water equivalent, with a confidence interval ranging between 739.5 and 989 mm. Data obtained in previous research from satellite-borne radars, and the ERA-Interim reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) provide lower yearly totals: 655 mm for ERA-Interim and 679 mm for the climatological data over DDU. ERA-Interim overestimates the occurrence of low-intensity precipitation events especially in summer, but it compensates for them by underestimating the snowfall amounts carried by the most intense events. Overall, this paper provides insightful examples of the added values of precipitation monitoring in Antarctica with a synergistic use of in situ and remote sensing measurements.

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Aerosol Assimilation of lidar data from Satellite (AEOLUS) and Ground-based (EARLINET) instruments in COMPO-IFS.

10.5194/egusphere-egu21-4799 ◽

2021 ◽

Author(s):

Julie Letertre-Danczak ◽

Angela Benedetti ◽

Drasko Vasiljevic ◽

Alain Dabas ◽

Thomas Flament ◽

...

Keyword(s):

Quality Data ◽

Lidar Data ◽

Operational Model ◽

Weather Forecasts ◽

The Past ◽

Medium Range ◽

First Results ◽

Monitoring Service ◽

The Vertical Distribution ◽

Good Quality Data

Since several years, the number of aerosol data coming from lidar has grown and improved in quality. These new datasets are providing a valuable information on the vertical distribution of aerosols which is missing in the AOD (Aerosol Optical Depth), which has been used so far in aerosols analysis. The launch of AEOLUS in 2018 has increased the interest in the assimilation of the aerosol lidar information. In parallel, the ground-based network EARLINET (European Aerosol Research LIdar NETwork) has grown to cover the Europe with good quality data. Assimilation of these data in the ECMWF/CAMS (European Centre for Medium-range Weather Forecasts / Copernicus Atmosphere Monitoring Service) system is expected to provide improvements in the aerosol analyses and forecasts. Three preliminary studies have been done in the past four years using AEOLUS data (A3S-ESA funded) and EARLINET data (ACTRIS-2 and EUNADIC-AV, EU-funded). These studies have allowed the full development of the tangent linear and adjoint code for lidar backscatter in the ECMWF's 4D-VAR system. These developments are now in the operational model version in research mode. The first results are promising and open the path to more intake of aerosol lidar data for assimilation purposes. The future launch of EARTHCARE (Earth-Cloud Aerosol and Radiation Explorer) and later ACCP (Aerosol Cloud, Convention and Precipitation) might even upgrade the use of aerosol lidar data in COMPO-IFS (Composition-Integrated Forecast system). The most recent results using AEOLUS data (for October 2019 and April 2020) and using EARLINET data (October 2020) will be shown in this presentation. The output will be compared to the CAMS operational aerosol forecast as well as to independent data from AERONET (AErosol Robotic NETwork).

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On the Albedo of Snow in Antarctica: A Contribution to I.A.G.O.

Journal of Glaciology ◽

10.3189/s0022143000009011 ◽

1988 ◽

Vol 34 (116) ◽

pp. 19-25 ◽

Cited By ~ 3

Author(s):

Gerd Wendler ◽

John Kelley

Keyword(s):

Simple Model ◽

Diurnal Variation ◽

Austral Summer ◽

Cloud Amount ◽

Mechanical Action ◽

List Type ◽

Solar Elevation ◽

Solar Noon ◽

Terre Adélie ◽

Very High

AbstractAs part of a larger experiment, detailed albedo measurements were carried out during the austral summer of 1985-86 in the dry-snow zone (1560 m) of Terre Adélie, eastern Antarctica. The following results were found:(1)Mean albedo values were high (around 82.6%). On clear days, the albedo showed some dependency on the solar elevation. The dependency was slight for solar elevations above 12° but became larger with low Sun angles.(2)The albedo was found to be a function of cloud amount and type, increasing with the amount and thickness of clouds. In white-out conditions, very high albedos were found (>90%).(3)The albedo showed a dependency on the type of snow. New snow displayed higher values than older snow, whose crystals had been destroyed by mechanical action.(4)A simple model was developed to assess the influence of sastrugi on the albedo. This model could explain the asymmetric diurnal variation about solar noon of the measured albedo above a sastrugi field.The above four dependencies might explain the considerable discrepancies which can be found in the literature concerning the snow albedo of Antarctica.

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Identification of blowing snow particles in images from a multi-angle snowflake camera

10.5194/tc-2018-248 ◽

2018 ◽

Cited By ~ 1

Author(s):

Mathieu Schaer ◽

Christophe Praz ◽

Alexis Berne

Keyword(s):

Austral Summer ◽

Gaussian Mixture ◽

Second Step ◽

Blowing Snow ◽

Kappa Score ◽

Probabilistic Information ◽

Complex Interactions ◽

Field Campaigns ◽

Number Of Particles ◽

Image Frequency

Abstract. A new method to automatically discriminate between hydrometeors and blowing snow particles on Multi-Angle Snowflake Camera (MASC) images is introduced. The method uses four selected descriptors related to the image frequency, the number of particles detected per image as well as their size and geometry to classify each individual image. The classification task is achieved with a two components Gaussian Mixture Model fitted on a subset of representative images of each class from field campaigns in Antarctica and Davos, Switzerland. The performance is evaluated by labelling the subset of images on which the model was fitted. An overall accuracy and Cohen's Kappa score of 99.4 and 98.8 %, respectively, is achieved. In a second step, the probabilistic information is used to flag images composed of a mix of blowing snow particles and hydrometeors, which turns out to occur frequently. The percentage of images belonging to each class from an entire austral summer in Antartica and during a winter in Davos, respectively, are presented. The capability to distinguish precipitation, blowing snow and a mix of those in MASC images is highly relevant to disentangle the complex interactions between wind, snowflakes and snowpack close to the surface.

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Probing the Fog Life Cycles in the Namib Desert

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-18-0142.1 ◽

2019 ◽

Vol 100 (12) ◽

pp. 2491-2507 ◽

Cited By ~ 4

Author(s):

Robert Spirig ◽

Roland Vogt ◽

Jarl Are Larsen ◽

Christian Feigenwinter ◽

Andreas Wicki ◽

...

Keyword(s):

Meteorological Data ◽

Life Cycles ◽

Cloud Base ◽

Spatial And Temporal Patterns ◽

Liquid Water Path ◽

Field Campaign ◽

First Results ◽

Fog Deposition ◽

Intensive Observation ◽

Observation Period

Abstract An intensive observation period was conducted in September 2017 in the central Namib, Namibia, as part of the project Namib Fog Life Cycle Analysis (NaFoLiCA). The purpose of the field campaign was to investigate the spatial and temporal patterns of the coastal fog that occurs regularly during nighttime and morning hours. The fog is often linked to advection of a marine stratus that intercepts with the terrain up to 100 km inland. Meteorological data, including cloud base height, fog deposition, liquid water path, and vertical profiles of wind speed/direction and temperature, were measured continuously during the campaign. Additionally, profiles of temperature and relative humidity were sampled during five selected nights with stratus/fog at both coastal and inland sites using tethered balloon soundings, drone profiling, and radiosondes. This paper presents an overview of the scientific goals of the field campaign; describes the experimental setup, the measurements carried out, and the meteorological conditions during the intensive observation period; and presents first results with a focus on a single fog event.

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New maps of the ice thickness and subglacial topography in Dronning Maud Land, Antarctica, determined by means of airborne radio-echo sounding

Annals of Glaciology ◽

10.3189/172756499781821409 ◽

1999 ◽

Vol 29 ◽

pp. 267-272 ◽

Cited By ~ 29

Author(s):

D. Steinhage ◽

U. Nixdorf ◽

U. Meyer ◽

H. Miller

Keyword(s):

Three Dimensional ◽

Austral Summer ◽

Ice Thickness ◽

Ice Volume ◽

Site Survey ◽

Radio Echo Sounding ◽

First Results ◽

Dronning Maud Land ◽

Subglacial Topography ◽

Echo Sounding

AbstractSince the austral summer of 1994-95 the Alfred Wegener Institute has carried out airborne radio-echo sounding (RES) measurements in Antarctica with its newly designed RES system. Since 1995-96 an ongoing pre-site survey for an ice-coring drill site in Dronning Maud Land has been carried out as part of the European Project for Ice Goring in Antarctica. The survey covers an area of 948 000 km2, with >49 500 km of airborne RES obtained from >200 hours of flight operation flown during the period 1994-97. In this paper, first results of the airborne RES survey are graphically summarized as newly derived maps of the ice thickness and subglacial topography, as well as a three-dimensional view of surface and subglacial bed and outcrop topography, revealing a total ice volume of 1.48 x 106 km3.

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The response of the Ekströmisen (Antarctica) grounding zone to tidal forcing

Annals of Glaciology ◽

10.3189/172756499781821247 ◽

1999 ◽

Vol 29 ◽

pp. 239-242 ◽

Cited By ~ 15

Author(s):

Björn Riedel ◽

Uwe Nixdorf ◽

Michael Heinert ◽

Alfons Eckstaller ◽

Christoph Mayer

Keyword(s):

Vertical Component ◽

Austral Summer ◽

Ocean Tides ◽

Extensive Field ◽

Main Emphasis ◽

Grounding Line ◽

First Results ◽

Vertical Displacements ◽

Dronning Maud Land ◽

Data Processing Methods

AbstractDuring the austral summer 1996–97 an extensive field program with geophysical and geodetic observations was carried out in the vicinity of the grounding line of Ekstromisen, Dronning Maud Land, Antarctica. The main emphasis of the joint program was placed on continuous observations of the horizontal as well as the vertical component of the ice displacement across the grounding zone. Data-processing methods for the in parts discontinuous time series and the vertical displacements in the area of the grounding zone are described, and first results presented, with the focus on the influence of the ocean tides on grounded ice. Tidal-induced deflections with amplitudes of up to 0.15 m were recorded at a station on grounded ice 1 km from the grounding line.

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Evento de Precipitação Intensa Associado às Perturbações Ondulatórias dos Alísios Sobre o Estado de Alagoas.

Revista Brasileira de Geografia Física ◽

10.26848/rbgf.v13.07.p3195-3205 ◽

2020 ◽

Vol 13 (07) ◽

pp. 3195

Author(s):

Matheus José Arruda Lyra ◽

Ismael Guidson Farias Freitas ◽

Dimas De Barros Santiago

Keyword(s):

Reanalysis Data ◽

Wave Disturbance ◽

Precipitation Event ◽

Trade Winds ◽

Climatological Data ◽

Weather Forecasts ◽

Global Era ◽

Medium Range ◽

Strong Convection ◽

High Level

O estudo teve como objetivo analisar a forte convecção provocada por uma Perturbação Ondulatória dos Alísios (POA) sobre o estado de Alagoas no dia 27 de maio de 2017. A análise e previsão de sistemas dessa magnitude desperta interesse devido os fenômenos adversos provocados e consequências à população. Foram utilizados dados de reanálise global ERA Interim fornecidos pelo European Centre for Medium-Range Weather Forecasts (ECMWF) com resolução espacial de 0,75º de latitude x 0,75º de longitude. Estes dados foram utilizados no software OpenGrADS para plotagem dos campos meteorológicos para a análise sinótica. Os dados referentes à precipitação acumulada foram fornecidos pela Secretaria de Estado do Meio Ambiente e dos Recursos Hídricos (SEMARH) a partir de 25 estações meteorológicas espalhadas por Alagoas. A perturbação se desenvolveu após a passagem de um sistema frontal que atingiu o Nordeste do Brasil alguns dias antes. O sistema sinótico pôde ser observado no campo de pressão à nível do mar e através das linhas de correntes em baixos níveis (925 e 850hPa) entre os dias 26 e 27, onde o eixo do cavado se concentrou sobre o estado de Alagoas. Os campos do fluxo de umidade integrado na vertical indicaram valores bastante elevados provenientes do Atlântico, adentrando Alagoas entre os dias 25 e 27. Através da análise da série de dados climatológica, maio de 2017 registrou o terceiro maior pico de pluviometria (692mm/24h), onde somente no dia 27 foram registrados 173mm/24h, o que correspondeu à cerca de 25% da média histórica. Intense Precipitation Event Provoked by the Wave Disturbance of Trade Winds Over the Alagoas State A B S T R A C TThe main objective of this study was to analyze the Wave Disturbance of Trade Winds (WDTW) dynamics that provoked strong rainfall over the Alagoas state on May 27 of 2017. The analysis and systems forecasting of this magnitude arouses interest due to the adverse phenomena caused and consequences to the population. Global ERA Interim reanalysis data was provided by the European Center for Medium-Range Weather Forecasts (ECMWF) with spatial resolution of 0.75º latitude x 0.75º longitude. This dataset was used in conjunction with OpenGrADS software to the meteorological fields plot for synoptic analysis. Precipitation dataset were collected from 25 meteorological stations spread across the Alagoas state provided by the State Secretary for the Environment and Water Resources (SEMARH). The disturbance developed after a frontal system passage that reached BNE a few days earlier. The synoptic system could be observed in the pressure at sea level field and through the streamlines at low levels (925 and 850hPa) between 26 and 27 of May, where the Trough axis was concentrated over Alagoas. The strong convection was also driven by a high-level Trough, lasted from 30ºS. The vertical integrated moisture flow fields indicated very high values from the Atlantic Ocean, reaching Alagoas between 25th and 27 of May. Through the analysis of climatological data, in May 2017 was registered the third highest peak of rainfall (692 mm/24h), where only on the 27th 173 mm/24h was recorded, which corresponded to the fence 25% of the historical average.Keywords: WDTW; Adverse Phenomena, Alagoas.

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Identification of blowing snow particles in images from a Multi-Angle Snowflake Camera

The Cryosphere ◽

10.5194/tc-14-367-2020 ◽

2020 ◽

Vol 14 (1) ◽

pp. 367-384 ◽

Cited By ~ 2

Author(s):

Mathieu Schaer ◽

Christophe Praz ◽

Alexis Berne

Keyword(s):

Austral Summer ◽

Gaussian Mixture ◽

Second Step ◽

Blowing Snow ◽

Kappa Score ◽

Probabilistic Information ◽

Complex Interactions ◽

Field Campaigns ◽

Number Of Particles ◽

Image Frequency

Abstract. A new method to automatically discriminate between hydrometeors and blowing snow particles on Multi-Angle Snowflake Camera (MASC) images is introduced. The method uses four selected descriptors related to the image frequency, the number of particles detected per image, and their size and geometry to classify each individual image. The classification task is achieved with a two-component Gaussian mixture model fitted on a subset of representative images of each class from field campaigns in Antarctica and Davos, Switzerland. The performance is evaluated by labeling the subset of images on which the model was fitted. An overall accuracy and a Cohen kappa score of 99.4 % and 98.8 %, respectively, are achieved. In a second step, the probabilistic information is used to flag images composed of a mix of blowing snow particles and hydrometeors, which turns out to occur frequently. The percentage of images belonging to each class from an entire austral summer in Antarctica and during a winter in Davos, respectively, is presented. The capability to distinguish precipitation, blowing snow and a mix of those in MASC images is highly relevant to disentangle the complex interactions between wind, snowflakes and snowpack close to the surface.

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Climatology of Anticyclonic and Cyclonic Rossby Wave Breaking on the Dynamical Tropopause in the Southern Hemisphere

Journal of Climate ◽

10.1175/2010jcli3157.1 ◽

2011 ◽

Vol 24 (4) ◽

pp. 1239-1251 ◽

Cited By ~ 7

Author(s):

Jie Song ◽

Chongyin Li ◽

Jing Pan ◽

Wen Zhou

Keyword(s):

Southern Hemisphere ◽

Rossby Wave ◽

Zonal Wind ◽

Potential Vorticity ◽

Wave Breaking ◽

Austral Summer ◽

Austral Winter ◽

Rossby Wave Breaking ◽

Weather Forecasts ◽

Medium Range

Abstract The characteristics of the climatological distribution of the anticyclonic (LC1) and cyclonic (LC2) Rossby wave breaking (RWB) in the Southern Hemisphere (SH) are investigated by calculating the occurrence frequency of the LC1- and LC2-like stratospheric potential vorticity (PV) streamers in the SH during the austral summer [December–February (DJF)] and wintertime [June–August (JJA)] on several isentropic surfaces by using the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) daily dataset. The results show that 1) on the equatorward flank of the climatological midlatitude jet (MLJ), the LC1-like PV streamers are frequently found over the central oceanic regions, whereas the LC2-like PV streamers are almost absent. On the poleward flank of the climatological MLJ, both types of PV streamers are frequently observed and the LC2-like PV streamers predominate; 2) the regions where the occurrences of the PV streamers are frequent overlap the weak zonal wind regions; and 3) in austral winter, a “double-jet” setting is evident in two regions of the SH [the double-jet upstream (DU) and the spilt jet region]. In the double-jet setting regions, the LC1-like PV streamers are frequently found both in the DU and the split-jet regions, while the occurrence of the LC2-like PV streamers is frequent in the split-jet region but is rather infrequent in the DU region.

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