scholarly journals Comparison of quasi-biennial oscillations of stratospheric winds and atmospheric temperatures at different altitudes

MAUSAM ◽  
2021 ◽  
Vol 49 (2) ◽  
pp. 223-228
Author(s):  
R. P. KANE
Keyword(s):  
Spectral Analysis ◽  
Atmospheric Pressure ◽  
North Pole ◽  
Sea Surface ◽  
Considerable Influence ◽  
Average Spacing ◽  
Zonal Winds ◽  
Stratospheric Wind ◽  
Different Altitudes ◽  
Prominent Peak

During 1959-89, the 12-month running means of 50 hPa zonal winds, the average atmospheric temperatures in the northern and southern hemisphere at four altitude slabs (950 hPa, 850- 300 hPa, 300-100 hPa and 100-50 hPa), Pacific and Atlantic sea surface temperature (SST) and-30hPa temperatures at North Pole and average for (10°-90° N), all showed quasi-biennial oscillations (QBO). However, whereas the wind QBO had an average spacing of 29 months, only temperatures at 300-100 hPa and Atlantic SST had similar average spacing. Other temperatures as also SO index (represented by Tahiti minus Darwin atmospheric pressure) had larger average spacing. Spectral analysis showed that whereas wind QBO had only one prominent peak at T=2.33 years, other parameters had weak QBOs near T=2.5-2.6 years except Pacific SST and 30 hPa North Pole temperature which had small peaks near T=2.3 years. All the temperatures had prominent peaks in the 3-6 year region which matched with similar peaks in the SO index. There is some indication that stratospheric wind QBO had some relation with parameters at all altitudes in tropics and with North Pole, while ENSO had considerable influence at other latitudes/altitudes.

scholarly journals The contribution of Geomatics to increase safety and security in ports

2021 ◽  
Author(s):  
Maurizio Soldani
Keyword(s):  
Atmospheric Pressure ◽  
Research Team ◽  
Environmental Parameters ◽  
Sea Surface ◽  
Port Security ◽  
Process Data ◽  
Water Quality Control ◽  
Port Authorities ◽  
Graphical Interfaces ◽  
Port Areas

AbstractIn this paper, the advantages achievable from the use of two prototype systems that are being developed to increase safety and security in ports are shown. Both systems start by monitoring environmental parameters in harbors, and then process data acquired. The first system has been conceived to be helpful to port communities (port authorities, pilots) to optimize harbor waterside management (ship’s navigation and cargo, dock performances, boat moorings, refloating of stranded ships, water quality control). By monitoring and processing sea level and atmospheric pressure in port areas, it can help port communities, e.g., to choose the best time when a ship with a certain draft can enter or leave a harbor, or to plan the best route inside the basin for that vessel (port safety). The second system, instead, has been designed for port protection purposes: by monitoring and processing the Earth’s magnetic field below the sea surface in harbors (where the natural field is disturbed by a high artificial component), it is able to detect the possible presence of intruders (e.g., divers) swimming underwater in prohibited areas (port security). Here, the results of monitoring and processing activities of the two systems performed in Livorno and La Spezia harbors are shown (Italy). The processing procedures and the graphical interfaces of the systems are based on applications under development by the research team the author belongs to, by using C# and C++ languages; Matlab environment has been employed for simulations.

scholarly journals INTRA-SEASONAL VARIABILITY OF NEAR-BOTTOM CURRENT IN THE HALMAHERA SEA

2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Marlin C Wattimena ◽  
Agus S Atmadipoera ◽  
Mulia Purba ◽  
Ariane Koch-Larrouy
Keyword(s):  
Pacific Ocean ◽  
Seasonal Variability ◽  
Sea Surface Height ◽  
Equatorial Pacific ◽  
Internal Tides ◽  
Sea Surface ◽  
Bottom Current ◽  
Equatorial Pacific Ocean ◽  
Mean Flow ◽  
Zonal Winds

The secondary entry portal of the Indonesian Throughflow (ITF) from the Pacific to Indian Oceans is considered to be via the Halmahera Sea (HS). However, few ITF studies have been done within the passage. This motivated the Internal Tides and Mixing in the Indonesian Througflow (INDOMIX) program to conduct direct measurements of currents and its variability across the eastern path of the ITF. This study focused on the intra-seasonal variability of near-bottom current in HS (129°E, 0°S), its origin and correlation with surface zonal winds and sea surface height over the equatorial Pacific Ocean. The result showed a strong northwestward mean flow with velocity exceeding 40 cm/s, which represented the current-following topography with the northwest orientation. Meridional current component was much stronger than the zonal component. The energy of power spectral density (PSD) of the current peaked on 14-days and 27-days periods. The first period was presumably related to the tidal oscillation, but the latter may be associated with surface winds perturbation. Furthermore, cross-PSD revealed a significant coherency between the observed currents and the surface zonal winds in the central equatorial Pacific zonal winds (180°E-160°W), which corroborates westward propagation of intra-seasonal sea surface height signals along the 5°S with its mean phase speeds of 50 cm/s, depicting the low-latitude westward Rossby waves on intra-seasonal band. Keywords: current, equatorial Pacific Ocean,  zonal winds, sea surface height, Halmahera Sea

scholarly journals Optimizing the Definition of a Sudden Stratospheric Warming

2018 ◽  
Vol 31 (6) ◽  
pp. 2337-2344 ◽  
Author(s):  
Amy H. Butler ◽  
Edwin P. Gerber
Keyword(s):  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Systematic Analysis ◽  
Wave Forcing ◽  
Zonal Winds ◽  
Stratospheric Temperature ◽  
Stratospheric Wind ◽  
Definition Of ◽  
Access To Data ◽  
The Continuum

Various criteria exist for determining the occurrence of a major sudden stratospheric warming (SSW), but the most common is based on the reversal of the climatological westerly zonal-mean zonal winds at 60° latitude and 10 hPa in the winter stratosphere. This definition was established at a time when observations of the stratosphere were sparse. Given greater access to data in the satellite era, a systematic analysis of the optimal parameters of latitude, altitude, and threshold for the wind reversal is now possible. Here, the frequency of SSWs, the strength of the wave forcing associated with the events, changes in stratospheric temperature and zonal winds, and surface impacts are examined as a function of the stratospheric wind reversal parameters. The results provide a methodical assessment of how to best define a standard metric for major SSWs. While the continuum nature of stratospheric variability makes it difficult to identify a decisively optimal threshold, there is a relatively narrow envelope of thresholds that work well—and the original focus at 60° latitude and 10 hPa lies within this window.

scholarly journals Stratospheric semi-decadal oscillations in NCEP data

2008 ◽  
Vol 26 (8) ◽  
pp. 2143-2157 ◽  
Author(s):  
H. G. Mayr ◽  
J. G. Mengel ◽  
F. T. Huang ◽  
E. R. Talaat ◽  
E. R. Nash ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Data Analysis ◽  
Temperature Data ◽  
Spectral Features ◽  
Altitude Range ◽  
Quasi Biennial Oscillation ◽  
Atmospheric Research ◽  
Zonal Winds ◽  
Environmental Prediction ◽  
Biennial Oscillation

Abstract. An analysis of the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) data is presented to provide a more complete description of the stratospheric 5-year semi-decadal (SD) oscillation (Mayr et al., 2007). The zonal-mean temperature and zonal wind data from the Atmospheric Research R-1 analysis are employed, covering the years from 1962 to 2002 in the altitude range from 10 to 30 km. For diagnostic purposes, the data are separated into the hemispherically symmetric and anti-symmetric components, and spectral analysis is applied to identify the signatures of the SD oscillations. Through the synthesis or filtering of spectral features, the SD modulations of the annual oscillation (AO) and quasi-biennial oscillation (QBO) are delineated. In agreement with the earlier findings, the magnitude of the SD oscillation is more pronounced when the 30-month QBO dominates during the years from 1975 to 1995. This is consistent with results from a numerical model, which shows that such a QBO generates the SD oscillation through interaction with the 12-month AO. In the zonal winds, the SD oscillation in the NCEP data is confined to equatorial latitudes, where it modulates the symmetric AO and QBO by about 5 m/s below 30 km. In the temperature data, the effect is also seen around the equator, but it is much larger at polar latitudes where the SD oscillation produces variations as large as 2 K. Our data analysis indicates that the SD oscillation is mainly hemispherically symmetric, and it appears to originate at equatorial latitudes where most of the energy resides.

The herring swimbladder: loss and gain of gas

1984 ◽  
Vol 64 (2) ◽  
pp. 441-459 ◽  
Author(s):  
J. H. S. Blaxter ◽  
R. S. Batty
Keyword(s):  
Pressure Vessel ◽  
Atmospheric Pressure ◽  
Juvenile Fish ◽  
Gas Diffusion ◽  
Sea Surface ◽  
Target Strength ◽  
Experimental Conditions ◽  
Neutral Buoyancy ◽  
Sea Bed ◽  
Ecological Implications

The herring is a physostome with no gas secretion mechanism in the swimbladder. The swimbladder volume was measured in fish from about 3–33 cm in length. It was rarely large enough to give the fish neutral buoyancy at the sea surface. Swimbladder volumes were also measured after periods of up to 1 week at pressures from 1·9 to 5·5 ATA (0·9–4·5atm above atmospheric pressure) in a laboratory pressure vessel and in a sub-surface cage in the sea. The swimbladder gas was lost within a few hours in the larval herring and in a few days in smaller juvenile fish; no change was found in older fish under experimental conditions. The findings were in accord with measurements of the guanine content of the swimbladder wall which was low in those fish which lost gas quickly. This supports the view that gas diffusion is limited by guanine crystals. While it seems likely that larger fish can exist for several weeks without the need to replenish the swimbladder gas some large spawning herring were caught at sea with empty swimbladders, suggesting a long stay near the sea bed. Analysis of swimbladder gas showed that oxygen tended to diffuse out more quickly than nitrogen. Behaviour experiments showed that fish with artificially emptied swimbladders could refill them by swallowing air at the surface, in some cases very quickly and efficiently. Fish with empty swimbladders and no access to the surface suffered a high mortality. The ecological implications of these results and their relevance to the interpretation of sonar ‘target strength’ measurements are discussed.

scholarly journals Derivation of Three-Dimensional Radiation Stress Based on Lagrangian Solutions of Progressive Waves

2017 ◽  
Vol 47 (11) ◽  
pp. 2829-2842 ◽  
Author(s):  
Chao Ji ◽  
Qinghe Zhang ◽  
Yongsheng Wu
Keyword(s):  
Coordinate Transformation ◽  
Atmospheric Pressure ◽  
Three Dimensional ◽  
Sea Surface ◽  
Lagrangian Description ◽  
Radiation Stress ◽  
New Approach ◽  
Progressive Waves ◽  
Analytical Expressions ◽  
Sloping Bottom

AbstractA new approach has been proposed to derive the expressions for three-dimensional radiation stress using solutions of the pressure and velocity distributions and the coordinate transformation function that are derived from a Lagrangian description wherein the pressure is zero (relative to the atmospheric pressure) at the sea surface. Using this approach, analytical expressions of horizontal and vertical depth-dependent radiation stress are derived at a uniform depth and for a sloping bottom, respectively. The results of the depth integration of the expressions agree well with the theory of Longuet-Higgins and Stewart. In the case involving a sloping bottom, the radiation stress expressions from this study provide a better balance of the net momentum compared to those from previous studies.

Experimental and Modeling Study of Atmospheric Pressure Effects on Ignition of Pine Wood at Different Altitudes

2010 ◽  
Vol 24 (1) ◽  
pp. 609-615 ◽  
Author(s):  
Jiakun Dai ◽  
Lizhong Yang ◽  
Xiaodong Zhou ◽  
Yafei Wang ◽  
Yupeng Zhou ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Pressure Effects ◽  
Pine Wood ◽  
Different Altitudes ◽  
Modeling Study

scholarly journals The Determination of Pressure Drop of Filter Rods and Nozzles under Different Atmospheric Pressure Conditions/Messung des Zugwiderstandes von Filterstäben und Düsen unter verschiedenen Luftdruckbedingungen

1969 ◽  
Vol 5 (1) ◽  
pp. 28-33
Author(s):  
E. Erxleben ◽  
A. Vorwerk
Keyword(s):  
Pressure Drop ◽  
Atmospheric Pressure ◽  
External Pressure ◽  
Considerable Degree ◽  
Reference Mark ◽  
Measuring Range ◽  
Standard Pressure ◽  
Air Circulation ◽  
Different Altitudes

AbstractThe relations between the pressure drop values of filter rods and nozzles obtained by customary gauges and the atmospheric pressure are investigated. Measurements are carried out between 500 and 1.000 mm Hg external pressure. This range was produced artificially. In case of filter rods it is shown, that a variation of 4 % only is received on the full measuring range by operating at constant air circulation (cm3/s) independent of atmospheric pressure. This shift is negligible in view of normally occurring local variations of atmospheric pressure. By operating at constant air circulation (cm3/s) the value of the nozzles' pressure drop varies in considerable degree over the full measuring range. Using reference nozzles for devices of pressure drop determination at different altitudes therefore, either a correction of the reference mark fixed at a standard pressure is necessary, or the values for filter pressure drop are to be corrected. The corrections are indicated.

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