scholarly journals The surface layer observed by a high-resolution sodar at DOME C, Antarctica

2014 ◽  
Vol 56 (5) ◽  
Author(s):  
Stefania Argentini ◽  
Igor Petenko ◽  
Angelo Viola ◽  
Giangiuseppe Mastrantonio ◽  
Ilaria Pietroni ◽  
...  
Keyword(s):  
Surface Layer ◽  
Gravity Waves ◽  
High Frequency ◽  
Vertical Resolution ◽  
High Vertical Resolution ◽  
One Year ◽  
Atmospheric Gravity ◽  
Radiation Measurements ◽  
High Range

<p>One year field experiment has started on December 2011 at the French - Italian station of Concordia at Dome C, East Antarctic Plateau. The objective of the experiment is the study of the surface layer turbulent processes under stable/very stable stratifications, and the mechanisms leading to the formation of the warming events. A sodar was improved to achieve the vertical/time resolution needed to study these processes. The system, named Surface Layer sodar (SL-sodar), may operate both in high vertical resolution (low range) and low vertical resolution (high range) modes. <em>In situ</em> turbulence and radiation measurements were also provided in the framework of this experiment. A few preliminary results, concerning the standard summer diurnal cycle, a summer warming event, and unusually high frequency boundary layer atmospheric gravity waves are presented.</p>

Daytime and nighttime turbulence on Mars monitored by InSight

2020 ◽  
Author(s):  
Aymeric Spiga ◽  
Naomi Murdoch ◽  
Don Banfield ◽  
Ralph Lorenz ◽  
Claire Newman ◽  
...  
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Seismic Signal ◽  
Atmospheric Science ◽  
Large Eddy Simulations ◽  
Dust Devil ◽  
Large Eddy ◽  
The Many ◽  
Convective Vortices

&lt;p&gt;The InSight instrumentation for atmospheric science combines high frequency, high accuracy and continuity. This makes InSight a mission particularly suitable for studies of the variability in the Planetary Boundary Layer (PBL) of Mars -- all the more since this topic is of direct interest for quake detectability given that turbulence is the main contributor to atmosphere-induced seismic signal. For the strong daytime buoyancy-driven PBL convection, InSight significantly extends the statistics of dust-devil-like convective vortices and turbulent wind gustiness, both of which are of strong interest for aeolian science. For the moderate nighttime shear-induced PBL convection, InSight enables to explore phenomena and variability left unexplored by previous in-situ measurements on Mars. In both daytime and nighttime environments, how the gravity waves and infrasound signals discovered by InSight are being guided within the PBL is also a central topic to InSight's atmospheric investigations, with the tantalizing possibility to identify possible sources for those phenomena. InSight has been operating at the surface of Mars since 18 months, thus the seasonal evolution of the many phenomena occurring in the PBL will be an emphasis of this report. Comparisons with turbulence-resolving modeling such as Large-Eddy Simulations will be also discussed.&lt;/p&gt;

scholarly journals Uncertainties of the Ocean Heat Content Estimation Induced by Insufficient Vertical Resolution of Historical Ocean Subsurface Observations

2014 ◽  
Vol 31 (6) ◽  
pp. 1383-1396 ◽  
Author(s):  
Lijing Cheng ◽  
Jiang Zhu
Keyword(s):  
Heat Content ◽  
Temporal Distribution ◽  
Observation System ◽  
Cold Bias ◽  
Vertical Resolution ◽  
Convex Shape ◽  
Global Average ◽  
High Vertical Resolution ◽  
The Difference

Abstract Assessment of the upper-ocean (0–700 m) heat content (OHC) is a key task for monitoring climate change. However, irregular spatial and temporal distribution of historical subsurface observations has induced uncertainties in OHC estimation. In this study, a new source of uncertainties in calculating OHC due to the insufficiency of vertical resolution in historical ocean subsurface temperature profile observations was diagnosed. This error was examined by sampling a high-vertical-resolution climatological ocean according to the depth intervals of in situ subsurface observations, and then the error was defined as the difference between the OHC calculated by subsampled profiles and the OHC of the climatological ocean. The obtained resolution-induced error appeared to be cold in the upper 100 m (with a peak of approximately −0.1°C), warm within 100–700 m (with a peak of ~0.1°C near 180 m), and warm when averaged over 0–700-m depths (with a global average of ~0.01°–0.025°C, ~1–2.5 × 1022 J). Geographically, it showed a warm bias within 30°S–30°N and a cold bias at higher latitudes in both hemispheres, the sign of which depended on the concave or convex shape of the vertical temperature profiles. Finally, the authors recommend maintaining an unbiased observation system in the future: a minimal vertical depth bin of 5% of the depth was needed to reduce the vertical-resolution-induced bias to less than 0.005°C on global average (equal to Argo accuracy).

scholarly journals Towards a method for high vertical resolution measurements of the partial pressure of CO2 within bulk sea ice

2012 ◽  
Vol 58 (208) ◽  
pp. 287-300 ◽  
Author(s):  
N.-X. Geilfus ◽  
B. Delille ◽  
V. Verbeke ◽  
J.-L. Tison
Keyword(s):  
Gas Chromatography ◽  
Sea Ice ◽  
Partial Pressure ◽  
Vertical Resolution ◽  
Gas Chromatograph ◽  
Partial Pressure Of Co2 ◽  
High Vertical Resolution ◽  
Non Destructive ◽  
Standard Gas

AbstractFluxes of atmospheric CO2 have been reported over sea ice during winter and spring. These fluxes are partly driven by the gradient of the CO2 concentration between sea ice and the atmosphere. We present a new non-destructive method to measure the pCO2 of bulk sea ice at its in situ temperature. This method is based on an equilibration procedure between sea ice and a standard gas of known CO2 concentration. The concentration is measured by gas chromatography with a precision of 5%. Tests were performed on artificial standard sea ice and confirmed the reproducibility of the technique in the range of precision of the gas chromatograph. To test the accuracy of this method, the first profiles of pCO2 measured in bulk sea ice are reported and compared with direct in situ measurements of brine pCO2 over depth-integrated intervals.

scholarly journals Seasonal and intra-diurnal variability of small-scale gravity waves in OH airglow at two Alpine stations

2018 ◽  
Author(s):  
Patrick Hannawald ◽  
Carsten Schmidt ◽  
René Sedlak ◽  
Sabine Wüst ◽  
Michael Bittner
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Phase Speed ◽  
Propagation Direction ◽  
Field Of View ◽  
Small Scale ◽  
Data Set ◽  
Diurnal Variability ◽  
Fully Automatic ◽  
One Year

Abstract. Between December 2013 and August 2017 the instrument FAIM (Fast Airglow IMager) observed the OH airglow emission at two Alpine stations. One year of measurements was performed at Oberpfaffenhofen, Germany (48.09° N, 11.28° E) and two years at Sonnblick, Austria (47.05° N, 12.96° E). Both stations are part of the Network for the detection of mesospheric change (NDMC). The temporal resolution is two frames per second and the field of view is 55 km × 60 km and 75 km × 90 km at the OH layer altitude of 87 km with a spatial resolution of 200 m and 280 m per pixel, respectively. This results in two dense datasets allowing precise derivation of horizontal gravity wave parameters. The analysis is based on a two-dimensional Fast Fourier Transform with fully automatic peak extraction. By combining the information of consecutive images time-dependent parameters such as the horizontal phase speed are extracted. The instrument is mainly sensitive to high-frequency small- and medium-scale gravity waves. A clear seasonal dependency concerning the meridional propagation direction is found for these waves in summer in direction to the summer pole. The zonal direction of propagation is eastwards in summer and westwards in winter. Investigations of the data set revealed an intra-diurnal variability, which may be related to tides. The observed horizontal phase speed and the number of wave events per observation hour are higher in summer than in winter.

scholarly journals Observations of in-situ generated gravity waves during a stratospheric temperature enhancement (STE) event

2011 ◽  
Vol 11 (22) ◽  
pp. 11913-11917 ◽  
Author(s):  
A. J. Gerrard ◽  
Y. Bhattacharya ◽  
J. P. Thayer
Keyword(s):  
Gravity Waves ◽  
Background Wind ◽  
Wind Fields ◽  
Vertical Wavelength ◽  
Stratospheric Temperature ◽  
Wave Parameters ◽  
Phase Progression ◽  
Temperature Enhancement ◽  
Atmospheric Gravity

Abstract. Evidence for in situ generated atmospheric gravity waves associated with a stratospheric temperature enhancement (STE) are presented. The signatures of two sets of gravity waves are observed by molecular-aerosol lidar in conjunction with the early December 2000 STE event above Sondrestrom, Greenland. The first set of gravity waves shows downward phase progression with a vertical wavelength of ~8 km while the second set shows upward phase progression with a vertical wavelength of ~9 km. With estimates of the background wind fields from synoptic analyses, the various intrinsic gravity wave parameters of these two wave structures are found. The observed wave features compare well to previous numerical modeling predictions.

scholarly journals In situ giant clam growth rate behavior in relation to temperature: A one-year coupled study of high-frequency noninvasive valvometry and sclerochronology

2011 ◽  
Vol 56 (5) ◽  
pp. 1940-1951 ◽  
Author(s):  
Caroline Schwartzmann ◽  
Gilles Durrieu ◽  
Mohamedou Sow ◽  
Pierre Ciret ◽  
Claire E. Lazareth ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Frequency ◽  
Giant Clam ◽  
Rate Behavior ◽  
One Year
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