Comparison of Ventilated and Unventilated Air Temperature Measurements in Inland Dronning Maud Land on the East Antarctic Plateau

2021 ◽  
Vol 38 (12) ◽  
pp. 2061-2070
Keyword(s):  
Austral Summer ◽  
Radiative Heating ◽  
Temperature Measurements ◽  
Shortwave Radiation ◽  
Relay Station ◽  
Antarctic Plateau ◽  
Temperature Bias ◽  
Dronning Maud Land ◽  
Weak Winds ◽  
Temperature Errors

Abstract Surface temperature measurements with naturally ventilated (NV) sensors over the Antarctic Plateau are largely subject to systematic errors caused by solar radiative heating. Here we examined the radiative heating error in Dronning Maud Land on the East Antarctic Plateau using both the newly installed automatic weather stations (AWSs) at NDF and Relay Station and the existing AWSs at Relay Station and Dome Fuji. Two types of NV shields were used in these AWSs: a multiplate radiation shield and a simple cylinder-shaped shield. In austral summer, the temperature bias between the force-ventilated (FV) sensor and the NV sensor never reached zero because of continuous sunlight. The hourly mean temperature errors reached up to 8°C at noon on a sunny day with weak wind conditions. The errors increased linearly with increasing reflected shortwave radiation and decreased nonlinearly with increasing wind speed. These features were observed in both the multiplate and the cylinder-shaped shields. The magnitude of the errors of the multiplate shield was much larger than that of the cylinder-shaped shield. To quantify the radiative errors, we applied an existing correction model based on the regression approach and successfully reduced the errors by more than 70% after the correction. This indicates that we can use the corrected temperature data instead of quality controlled data, which removed warm bias during weak winds in inland Dronning Maud Land.

scholarly journals Large spatial variation in accumulation rate in Jutulstraumen ice stream, Dronning Maud Land, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 231-238 ◽  
Author(s):  
Kjetil Melvold ◽  
Jon Ove Hagen ◽  
Jean Francis Pinglot ◽  
Niels Gunuestrup
Keyword(s):  
Mass Balance ◽  
Accumulation Rate ◽  
Austral Summer ◽  
Katabatic Winds ◽  
Surface Gradient ◽  
Ice Stream ◽  
Dronning Maud Land ◽  
Temporal And Spatial ◽  
Accumulation Trend ◽  
Local Accumulation

A mass-balance programme was initiated on Jutulstraumen ice stream, western Dronning Maud Land,Antarctica, during the austral summer 1992-93. As a part of the mass-balance programme, accumulation rate was measured along the centre line of Jutulstraumen from the shelf edge up to the plateau at about 2500 m a.s.l. Accumulation distribution obtained from seven shallow firn cores and 48 slake readings is presented. The overall net accumulation trend displays a decreasing accumulation with increasing elevation and distance to coast, but on both the mesoscale and microscale there are significant variations. This is due to complex patterns of precipitation controlled by orography and redistribution by katabatic winds. The local accumulation distribution (few km scale) was found to be dependent on downslope surface gradient (aspect north, northwest), and variations up to 100% were found over distances of less than 3 km. The large variation in accumulation is important when selecting new core sites and for interpretation of temporal and spatial variations in accumulation derived from firn cores.

Large Increase in Incident Shortwave Radiation due to the Ozone Hole Offset by High Climatological Albedo over Antarctica

2017 ◽  
Vol 30 (13) ◽  
pp. 4883-4890 ◽  
Author(s):  
G. Chiodo ◽  
L. M. Polvani ◽  
M. Previdi
Keyword(s):  
Surface Temperature ◽  
Ozone Depletion ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Surface Energy Budget ◽  
Ozone Hole ◽  
Radiative Heating ◽  
Shortwave Radiation ◽  
Stratospheric Ozone Depletion ◽  
Continental Scale

Despite increasing scientific scrutiny in recent years, the direct impact of the ozone hole on surface temperatures over Antarctica remains uncertain. Here, this question is explored by using the Community Earth System Model–Whole Atmosphere Community Climate Model (CESM-WACCM), contrasting two ensembles of runs with and without stratospheric ozone depletion. It is found that, during austral spring, the ozone hole leads to a surprisingly large increase in surface downwelling shortwave (SW) radiation over Antarctica of 3.8 W m−2 in clear sky and 1.8 W m−2 in all sky. However, despite this large increase in incident SW radiation, no ozone-induced surface warming is seen in the model. It is shown that the lack of a surface temperature response is due to reflection of most of the increased downward SW, resulting in an insignificant change to the net SW radiative heating. To first order, this reflection is simply due to the high climatological surface albedo of the Antarctic snow (97% in visible SW), resulting in a net zero ozone-induced surface SW forcing. In addition, it is shown that stratospheric ozone depletion has a negligible effect on longwave (LW) radiation and other components of the surface energy budget. These results suggest a minimal role for ozone depletion in forcing Antarctic surface temperature trends on a continental scale.

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

1999 ◽  
Vol 29 ◽  
pp. 267-272 ◽  
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.

Temperature control and calibration in quench furnaces and some new temperature measurements in the system CaO–MgO–Al2O3–SiO2

1969 ◽  
Vol 37 (285) ◽  
pp. 1-15 ◽  
Author(s):  
G. M. Biggar ◽  
M. J. O'Hara
Keyword(s):  
Temperature Control ◽  
Temperature Measurements ◽  
Temperature Errors ◽  
Invariant Equilibria

SummaryTechniques associated with temperature control and measurement in quench furnaces are described and a study made of calibration problems. Systematic temperature errors as great as 30°C in published results from separate laboratories are explicable. A comprehensive redetermination of temperatures of invariant equilibria in systems containing CaO, MgO, Al2O3, SiO2, Na2O, Fe-O2, has been initiated and the results to date are presented, including approximate determinations of three invariant equilibria in the system CaO-MgO-Al2O3-SiO2 involving liquid, monticellite, spinel, and two of merwinite, periclase, and forsterite, which are important in the melting of magnesia refractories, and precise determinations of the three newly recognized invariant equilibria involving liquid, spinel, diopside, and two of forsterite, melilite, and anorthite.

scholarly journals Strong-wind events and their influence on the formation of snow dunes: observations from Kohnen station, Dronning Maud Land, Antarctica

2010 ◽  
Vol 56 (199) ◽  
pp. 891-902 ◽  
Author(s):  
Gerit Birnbaum ◽  
Johannes Freitag ◽  
Ralf Brauner ◽  
Gert König-Langlo ◽  
Elisabeth Schulz ◽  
...  
Keyword(s):  
Austral Summer ◽  
Maximum Height ◽  
Strong Wind ◽  
Pressure System ◽  
Wind Speeds ◽  
Dronning Maud Land ◽  
Low Pressure System ◽  
The Mean ◽  
Wind Events ◽  
Drilling Site

AbstractAnalyses of shallow cores obtained at the European Project for Ice Coring in Antarctica (EPICA) drilling site Kohnen station (75°00′ S, 00°04′ E; 2892 m a.s.l.) on the plateau of Dronning Maud Land reveal the presence of conserved snow dunes in the firn. In situ observations during three dune formation events in the 2005/06 austral summer at Kohnen station show that these periods were characterized by a phase of 2 or 3 days with snowdrift prior to dune formation which only occurred during high wind speeds of >10 m s-1 at 2 m height caused by the influence of a low-pressure system. The dune surface coverage after a formation event varied between 5% and 15%, with a typical dune size of (4 ± 2) m × (8 ± 3) m, a maximum height of 0.2 ± 0.1 m and a periodicity length of about 30 m. The mean density within a snow dune varied between 380 and 500 kg m-3, whereas the mean density at the surrounding surface was 330 ± 5 kgm-3. The firn cores covering a time-span of 22 ± 2 years reveal that approximately three to eight events per year occurred, during which snow dunes had been formed and were preserved in the firn.

Solar and Thermal Radiation Errors on Upper-Air Radiosonde Temperature Measurements

2013 ◽  
Vol 30 (10) ◽  
pp. 2382-2393 ◽  
Author(s):  
R. Philipona ◽  
A. Kräuchi ◽  
G. Romanens ◽  
G. Levrat ◽  
P. Ruppert ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Thermal Radiation ◽  
Air Temperature ◽  
Weather Prediction ◽  
Lower Troposphere ◽  
Longwave Radiation ◽  
Atmospheric Temperature ◽  
Radiative Heating ◽  
Temperature Measurements ◽  
High Quality

Abstract Atmospheric temperature and humidity profiles are important for weather prediction, but climate change has increased the interest in upper-air observations asking for very high-quality reference measurements. This paper discusses an experimental approach to determine the radiation-induced error on radiosonde air temperature measurements. On the one hand, solar shortwave and thermal longwave radiation profiles were accurately measured during radiosonde ascents from the surface to 35-km altitude. On the other hand, air temperature was measured with several thermocouples on the same flight, simultaneously under sun-shaded and unshaded conditions. The radiation experiments reveal that thermal radiation errors on the very thin thermocouple of the Meteolabor SRS-C34 radiosonde are similar during night- and daytime. They produce a radiative cooling in the lower troposphere and the upper stratosphere, but a radiative heating in the upper troposphere and lower stratosphere. Air temperature experiments with several thermocouples, however, show that solar radiation produces a radiative heating of about +0.2°C near the surface, which linearly increases to about +1°C at 32 km (~10 hPa). The new solar radiation error profile was then applied to SRS-C34 measurements made during the Eighth WMO Intercomparison of High Quality Radiosonde Systems, held in Yangjiang, China, in July 2010. The effects of thermal and solar radiation errors are finally shown in contrast to the 10 other internationally used radiosonde systems, which were flown during this international campaign.

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

1999 ◽  
Vol 29 ◽  
pp. 239-242 ◽  
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.

scholarly journals GPS determination of the velocity and strain-rate fields on Schirmacher Glacier, central Dronning Maud Land, Antarctica

2007 ◽  
Vol 53 (183) ◽  
pp. 558-564 ◽  
Author(s):  
P.S. Sunil ◽  
C.D. Reddy ◽  
M. Ponraj ◽  
Ajay Dhar ◽  
D. Jayapaul
Keyword(s):  
Strain Rate ◽  
Austral Summer ◽  
Base Station ◽  
Spatially Correlated ◽  
The North ◽  
Schirmacher Oasis ◽  
Global Positioning ◽  
Dronning Maud Land ◽  
Insight Into

Global positioning system (GPS) campaigns were conducted during the 2003 and 2004 austral summer seasons to obtain insight into the velocity and strain-rate distribution on Schirmacher Glacier, central Dronning Maud Land, East Antarctica. GPS data were collected at 21 sites and analyzed to estimate the site coordinates, baselines and velocities. The short-term precision of the base station, MAIT, is estimated from the daily coordinate repeatability solutions during the two years. All GPS points on the glacier were constrained with respect to MAIT and nearby International GPS Service stations. Horizontal velocities of the glacier sites lie between 1.89 ± 0.01 and 10.88 ± 0.01 ma−1 to the north-northeast, with an average velocity of 6.21 ± 0.01 m a−1. The principal strain rates provide a quantitative measurement of extension rates, which range from (0.11 ± 0.01) × 10−3 to (1.48 ± 0.85) × 10−3a−1, and shortening rates, which range from (0.04 ± 0.02) × 10−3 to (0.96 ± 0.16) × 10−3a−1. The velocity and strain-rate distributions across the GPS network in Schirmacher Glacier are spatially correlated with topography, subsurface undulations, fracture zones/crevasses and the partial blockage of the flow by nunataks and the Schirmacher Oasis.

scholarly journals Nanorchestes Topsent and Trouessart, 1890 and Eupodes Koch, 1836 (Acari: Prostigmata) from Vestfjella mountain range, Antarctica

2002 ◽  
Vol 13 (4) ◽  
Author(s):  
Rtiva Niemi ◽  
Matti Uusitalo ◽  
Petri Lintinen
Keyword(s):  
Austral Summer ◽  
Mountain Range ◽  
Dronning Maud Land

Two terrestrial prostigmatid mites were found from the Audunfjellet nunatak, Vestfjella mountain range, in Dronning Maud Land, Antarctica during the FINNARP expedition in Austral summer 1997/1998. The mites are close to, if not identical to, Nanorchestes bifurcatus Strandtmann, 1967 and Eupodes tottanfjella Strandtmann, 1967, also earlier reported from the area, but identification cannot be verified by using the published descriptions. Samples were also collected from an unnamed nunatak and the Basen nunatak, but these were miteless by chance.

scholarly journals Representative surface snow density on the East Antarctic Plateau

2020 ◽  
Vol 14 (11) ◽  
pp. 3663-3685
Author(s):  
Alexander H. Weinhart ◽  
Johannes Freitag ◽  
Maria Hörhold ◽  
Sepp Kipfstuhl ◽  
Olaf Eisen
Keyword(s):  
Spatial Scales ◽  
Ice Sheets ◽  
Austral Summer ◽  
Sampling Strategy ◽  
Field Measurements ◽  
Mass Balances ◽  
Snow Density ◽  
Surface Mass ◽  
Antarctic Plateau ◽  
Surface Snow

Abstract. Surface mass balances of polar ice sheets are essential to estimate the contribution of ice sheets to sea level rise. Uncertain snow and firn densities lead to significant uncertainties in surface mass balances, especially in the interior regions of the ice sheets, such as the East Antarctic Plateau (EAP). Robust field measurements of surface snow density are sparse and challenging due to local noise. Here, we present a snow density dataset from an overland traverse in austral summer 2016/17 on the Dronning Maud Land plateau. The sampling strategy using 1 m carbon fiber tubes covered various spatial scales, as well as a high-resolution study in a trench at 79∘ S, 30∘ E. The 1 m snow density has been derived volumetrically, and vertical snow profiles have been measured using a core-scale microfocus X-ray computer tomograph. With an error of less than 2 %, our method provides higher precision than other sampling devices of smaller volume. With four spatially independent snow profiles per location, we reduce the local noise and derive a representative 1 m snow density with an error of the mean of less than 1.5 %. Assessing sampling methods used in previous studies, we find the highest horizontal variability in density in the upper 0.3 m and therefore recommend the 1 m snow density as a robust measure of surface snow density in future studies. The average 1 m snow density across the EAP is 355 kg m−3, which we identify as representative surface snow density between Kohnen Station and Dome Fuji. We cannot detect a temporal trend caused by the temperature increase over the last 2 decades. A difference of more than 10 % to the density of 320 kg m−3 suggested by a semiempirical firn model for the same region indicates the necessity for further calibration of surface snow density parameterizations. Our data provide a solid baseline for tuning the surface snow density parameterizations for regions with low accumulation and low temperatures like the EAP.

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