A study of boundary layer behavior associated with high NO concentrations at the South Pole using a minisodar, tethered balloon, and sonic anemometer

2008 ◽  
Vol 42 (12) ◽  
pp. 2762-2779 ◽  
Author(s):  
W NEFF ◽  
D HELMIG ◽  
A GRACHEV ◽  
D DAVIS
Keyword(s):  
Boundary Layer ◽  
Sonic Anemometer ◽  
South Pole ◽  
Tethered Balloon ◽  
The South ◽  
Layer Behavior

scholarly journals Turbulence fluxes and variances measured with a sonic anemometer mounted on a tethered balloon

2016 ◽  
Vol 9 (9) ◽  
pp. 4375-4386 ◽  
Author(s):  
Guylaine Canut ◽  
Fleur Couvreux ◽  
Marie Lothon ◽  
Dominique Legain ◽  
Bruno Piguet ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Frequency ◽  
Field Experiments ◽  
Sonic Anemometer ◽  
Motion Sensor ◽  
Tethered Balloon ◽  
Inertial Motion ◽  
Convective Boundary ◽  
Momentum Fluxes ◽  
Field Campaigns

Abstract. This study presents the first deployment in field campaigns of a balloon-borne turbulence probe, developed with a sonic anemometer and an inertial motion sensor suspended below a tethered balloon. This system measures temperature and horizontal and vertical wind at high frequency and allows the estimation of heat and momentum fluxes as well as turbulent kinetic energy in the lower part of the boundary layer. The system was validated during three field experiments with different convective boundary-layer conditions, based on turbulent measurements from instrumented towers and aircraft.

Deployment of a Tethered-Balloon System for Microphysics and Radiative Measurements in Mixed-Phase Clouds at Ny-Ålesund and South Pole

2011 ◽  
Vol 28 (5) ◽  
pp. 656-670 ◽  
Author(s):  
R. Paul Lawson ◽  
Knut Stamnes ◽  
Jakob Stamnes ◽  
Pat Zmarzly ◽  
Jeff Koskuliks ◽  
...  
Keyword(s):  
Mixed Phase ◽  
Radiative Properties ◽  
The Arctic ◽  
South Pole ◽  
Tethered Balloon ◽  
The South ◽  
Stratus Clouds ◽  
Mixed Phase Clouds ◽  
Instrument Package ◽  
Balloon System

Abstract A tethered-balloon system capable of making microphysical and radiative measurements in clouds is described and examples of measurements in boundary layer stratus clouds in the Arctic and at the South Pole are presented. A 43-m3 helium-filled balloon lofts an instrument package that is powered by two copper conductors in the tether. The instrument package can support several instruments, including, but not limited to, a cloud particle imager; a forward-scattering spectrometer probe; temperature, pressure, humidity, and wind sensors; ice nuclei filters; and a 4-π radiometer that measures actinic flux at 500 and 800 nm. The balloon can stay aloft for an extended period of time (in excess of 24 h) and conduct vertical profiles up to about 1–2 km, contingent upon payload weight, wind speed, and surface elevation. Examples of measurements in mixed-phase clouds at Ny-Ålesund, Svalbard (79°N), and at the South Pole are discussed. The stratus clouds at Ny-Ålesund ranged in temperature from 0° to −10°C and were mostly mixed phase with heavily rimed ice particles, even when cloud-top temperatures were warmer than −5°C. Conversely, mixed-phase clouds at the South Pole contained regions with only water drops at temperatures as cold as −32°C and were often composed of pristine ice crystals. The radiative properties of mixed-phase clouds are a critical component of radiative transfer in polar regions, which, in turn, is a lynch pin for climate change on a global scale.

Observations of summertime NO fluxes and boundary-layer height at the South Pole during ISCAT 2000 using scalar similarity

2004 ◽  
Vol 38 (32) ◽  
pp. 5389-5398 ◽  
Author(s):  
S.P. Oncley ◽  
M. Buhr ◽  
D.H. Lenschow ◽  
D. Davis ◽  
S.R. Semmer
Keyword(s):  
Boundary Layer ◽  
South Pole ◽  
The South ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Scalar Similarity ◽  
No Fluxes

scholarly journals Measurements of OH and RO<sub>2</sub> radicals at Dome C, East Antarctica

2014 ◽  
Vol 14 (10) ◽  
pp. 14999-15044 ◽  
Author(s):  
A. Kukui ◽  
M. Legrand ◽  
S. Preunkert ◽  
M. M. Frey ◽  
R. Loisil ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Oxidative Capacity ◽  
Local Times ◽  
Oh Radicals ◽  
Peroxy Radicals ◽  
South Pole ◽  
The South ◽  
Primary Radical ◽  
Antarctic Plateau ◽  
Photochemical Modelling

Abstract. Concentrations of OH radicals and the sum of peroxy radicals, RO2, were measured in the boundary layer for the first time on the East Antarctic Plateau at the Concordia Station (Dome C, 75.10° S, 123.31° E) during the austral summer 2011/2012. The median concentrations of OH and RO2 radicals were 3.1 × 106 molecule cm−3 and 9.9 × 107 molecule cm−3, respectively. These values are comparable to those observed at the South Pole, confirming that the elevated oxidative capacity of the Antarctic atmospheric boundary layer found at the South Pole is not restricted to the South Pole but common over the high Antarctic plateau. At Concordia, the concentration of radicals showed distinct diurnal profiles with the median maximum of 5.2 × 106 molecule cm−3 at 11:00 and the median minimum of 1.1 × 106 molecule cm−3 at 01:00 for OH radicals and 1.7 × 108 molecule cm−3 and 2.5 × 107 molecule cm−3 for RO2 radicals at 13:00 and 23:00, respectively (all times are local times). Concurrent measurements of O3, HONO, NO, NO2, HCHO and H2O2 demonstrated that the major primary source of OH and RO2 radicals at Dome C was the photolysis of HONO, HCHO and H2O2, with the photolysis of HONO contributing ∼75% of total primary radical production. However, photochemical modelling with accounting for all these radical sources overestimates the concentrations of OH and RO2 radicals by a factor of 2 compared to field observations. Neglecting the OH production from HONO in the photochemical modelling results in an underestimation of the concentrations of OH and RO2 radicals by a factor of 2. To explain the observations of radicals in this case an additional source of OH equivalent to about 25% of measured photolysis of HONO is required. Even with a factor of 4 reduction in the concentrations of HONO, the photolysis of HONO represents the major primary radical source at Dome C. Another major factor leading to the large concentration of OH radicals measured at Dome C was large concentrations of NO molecules and fast recycling of peroxy radicals to OH radicals.

scholarly journals The Meteorology and Chemistry of High Nitrogen Oxide Concentrations in the Stable Boundary Layer at the South Pole

2017 ◽  
Author(s):  
William Neff ◽  
Jim Crawford ◽  
Marty Buhr ◽  
John Nicovich ◽  
Gao Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Stable Boundary Layer ◽  
Early Summer ◽  
Late Spring ◽  
Small Scale ◽  
South Pole ◽  
The South ◽  
Stable Boundary ◽  
Direct Measurements ◽  
The Antarctic

Abstract. Four summer seasons of nitrogen oxide (NO) concentrations were obtained at the South Pole during the Sulfur Chemistry in the Antarctic Troposphere (ISCAT) program (1998 and 2000) and the Antarctic Tropospheric Chemistry Investigation (ANTCI) in (2003, 2006–7). Together, analyses of their data here provide insight into the large-to-small scale meteorology that sets the stage for high NO and the significant variability that occurs day-to-day, within seasons and year-to-year. In addition, these observations reveal the interplay between physical and chemical processes at work in the stable boundary layer of the high Antarctic plateau. We found a systematic evolution of the large-scale wind system over the ice sheet from winter to summer that controls the surface boundary layer and its effect on NO: Initially in early spring (Days 280–310) the transport of warm air and clouds over West Antarctica dominates the environment over the South Pole; In late spring (Days 310–340), of significance to NO, the winds at 300-hPa exhibit a bimodal behavior alternating between NW and SE; In early summer (Days 340–375), the flow aloft is dominated by winds from the Weddell Sea. During late spring, winds aloft from the SE are strongly associated with clear skies, shallow stable boundary layers, and light surface winds from the east: it is under these conditions that the highest NO occurs. Examination of the winds at 300 hPa from 1961 to 2013 shows that this seasonal pattern has not changed significantly although the last twenty years have seen an increasing trend in easterly surface winds at the South Pole. What has also changed is the persistence of the ozone hole, often into early summer. With lower total ozone column density and higher sun elevation, the highest actinic flux responsible for the photolysis of snow nitrate now occurs in late spring under the shallow boundary layer conditions optimum for high accumulation of NO. This may occur via the non-linear HOX-NOX chemistry proposed after the first ISCAT field programs and NOX recycling to the surface where quantum yields may be large under the low-snow-accumulation regime of the Antarctic plateau. During the 2003 field program a sodar made direct measurements of the stable boundary layer depth (BLD), a key factor in explaining the chemistry of the high NO concentrations. Because direct measurements were not available in the other years, we developed an estimator for BLD using direct observations obtained in 2003 and step-wise linear regression with meteorological data from a 22-m tower (that was tested against independent data obtained in 1993). These data were then used with assumptions about the column abundance of NO to estimate surface fluxes of NOX. These results agreed in magnitude with results at Concordia Station and confirmed significant daily, intraseasonal and interannual variability in NO and its flux from the snow surface. Finally, we found that synoptic to mesoscale eddies governed the boundary layer circulation and accumulation pathways for NO at the South Pole rather than katabatic forcing. It was the small scale features of the circulation including the transition from cloudy to clear conditions that set the stage for short-term extremes in NO whereas larger-scale features were associated with more moderate concentrations.

scholarly journals Measurements of OH and RO<sub>2</sub> radicals at Dome C, East Antarctica

2014 ◽  
Vol 14 (22) ◽  
pp. 12373-12392 ◽  
Author(s):  
A. Kukui ◽  
M. Legrand ◽  
S. Preunkert ◽  
M. M. Frey ◽  
R. Loisil ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Local Times ◽  
Oh Radicals ◽  
Peroxy Radicals ◽  
South Pole ◽  
The South ◽  
Primary Radical ◽  
Antarctic Plateau ◽  
Radical Production ◽  
Photochemical Modelling

Abstract. Concentrations of OH radicals and the sum of peroxy radicals, RO2, were measured in the boundary layer for the first time on the East Antarctic Plateau at the Concordia Station (Dome C, 75.10° S, 123.31° E) during the austral summer 2011/2012. The median concentrations of OH and RO2 radicals were 3.1 × 106 molecule cm−3 and 9.9 × 106 molecule cm−3, respectively. These values are comparable to those observed at the South Pole, confirming that the elevated oxidative capacity of the Antarctic atmospheric boundary layer found at the South Pole is not restricted to the South Pole but common over the high Antarctic plateau. At Concordia, the concentration of radicals showed distinct diurnal profiles with the median maximum of 5.2 × 106 molecule cm−3 at 11:00 and the median minimum of 1.1 × 106 molecule cm−3 at 01:00 for OH radicals and 1.7 × 108 molecule cm−3 and 2.5 × 107 molecule cm−3 for RO2 radicals at 13:00 and 23:00, respectively (all times are local times). Concurrent measurements of O3, HONO, NO, NO2, HCHO and H2O2 demonstrated that the major primary source of OH and RO2 radicals at Dome C was the photolysis of HONO, HCHO and H2O2, with the photolysis of HONO contributing ~75% of total primary radical production. However, photochemical modelling with accounting for all these radical sources overestimates the concentrations of OH and RO2 radicals by a factor of 2 compared to field observations. Neglecting the net OH production from HONO in the photochemical modelling results in an underestimation of the concentrations of OH and RO2 radicals by a factor of 2. To explain the observations of radicals in this case an additional source of OH equivalent to about (25–35)% of measured photolysis of HONO is required. Even with a factor of 5 reduction in the concentrations of HONO, the photolysis of HONO represents the major primary radical source at Dome C. To account for a possibility of an overestimation of NO2 observed at Dome C the calculations were also performed with NO2 concentrations estimated by assuming steady-state NO2 / NO ratios. In this case the net radical production from the photolysis of HONO should be reduced by a factor of 5 or completely removed based on the photochemical budget of OH or 0-D modelling, respectively. Another major factor leading to the large concentration of OH radicals measured at Dome C was large concentrations of NO molecules and fast recycling of peroxy radicals to OH radicals.

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