scholarly journals Influence of Atmospheric Circulation on Cloudiness and Cloud Types in Petuniabukta and Svalbard-Lufthavn in Summer 2016

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 724
Author(s):  
Leszek Kolendowicz ◽  
Marek Półrolniczak ◽  
Sebastian Kendzierski ◽  
Katarzyna Szyga-Pluta ◽  
Kamil Láska
Keyword(s):  
Atmospheric Circulation ◽  
Meteorological Parameters ◽  
Synoptic Situation ◽  
Sea Level Pressure ◽  
Atmospheric Research ◽  
Environmental Features ◽  
Statistical Measures ◽  
The Mean ◽  
Composite Maps ◽  
Cloud Patterns

The paper analyzes the influence of atmospheric circulation on cloudiness and cloud types during July and August of 2016 in Petuniabukta and Svalbard-Lufthavn. For the meteorological parameters, basic statistical measures were calculated and the average diurnal cloud patterns were analyzed. Taking the data from meteorological reanalysis (NCEP/NCAR-The National Centers for Atmospheric Prediction/The National Center for Atmospheric Research) regarding the mean sea-level pressure (SLP), 500 hPa geopotential height, and air temperature at 850 hPa (T850), composite maps of the synoptic situation for the studied area were constructed. For the observed types of clouds, the frequency of their occurrence in particular types of atmospheric circulation was then determined according to the Niedźwiedź classification. Differences in the amount of cloudiness in the examined measuring points were ascertained. The occurrence of cloud types is associated with both the direction of air mass advection and type of circulation. The results may also indicate the possibility of influence from specific, local environmental features on cloudiness.

Long-Term Wind Speed Trends over Australia

2012 ◽  
Vol 25 (1) ◽  
pp. 170-183 ◽  
Author(s):  
Alberto Troccoli ◽  
Karl Muller ◽  
Peter Coppin ◽  
Robert Davy ◽  
Chris Russell ◽  
...  
Keyword(s):  
Wind Speed ◽  
Atmospheric Circulation ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Long Period ◽  
The Mean ◽  
Strong Winds ◽  
Circulation Changes ◽  
Linear Trends

Abstract Accurate estimates of long-term linear trends of wind speed provide a useful indicator for circulation changes in the atmosphere and are invaluable for the planning and financing of sectors such as wind energy. Here a large number of wind observations over Australia and reanalysis products are analyzed to compute such trends. After a thorough quality control of the observations, it is found that the wind speed trends for 1975–2006 and 1989–2006 over Australia are sensitive to the height of the station: they are largely negative for the 2-m data but are predominantly positive for the 10-m data. The mean relative trend at 2 m is −0.10 ± 0.03% yr−1 (−0.36 ± 0.04% yr−1) for the 1975–2006 (1989–2006) period, whereas at 10 m it is 0.90 ± 0.03% yr−1 (0.69 ± 0.04% yr−1) for the 1975–2006 (1989–2006) period. Also, at 10 m light winds tend to increase more rapidly than the mean winds, whereas strong winds increase less rapidly than the mean winds; at 2 m the trends in both light and strong winds vary in line with the mean winds. It was found that a qualitative link could be established between the observed features in the linear trends and some atmospheric circulation indicators (mean sea level pressure, wind speed at 850 hPa, and geopotential at 850 hPa), particularly for the 10-m observations. Further, the magnitude of the trend is also sensitive to the period selected, being closer to zero when a very long period, 1948–2006, is considered. As a consequence, changes in the atmospheric circulation on climatic time scales appear unlikely.

scholarly journals Estimation of Radio Horizon Distance Using Measured Meteorological Parameters over Some Selected Locations in Nigeria

2019 ◽  
pp. 1-11
Author(s):  
A. T. Adediji ◽  
S. O. Adebusola ◽  
J. S. Ojo
Keyword(s):  
Relative Humidity ◽  
Data Acquisition ◽  
Meteorological Parameters ◽  
Mean Value ◽  
Dry Season ◽  
Wet Season ◽  
Atmospheric Research ◽  
Port Harcourt ◽  
Study Results ◽  
The Mean

In this study, results of the variation of maximum and minimum radio horizon distance derived from the computation of surface refractivity through measurement of temperature, relative humidity and pressureacrosssevenlocations((Akure (7.15°N, 5.12°E), Lagos (6.30°N, 3.20°E), Abuja (7.10°N, 9.25°E), Jos (9.50°N, 8.50°E), Makurdi (7.30°N,8.53°E), Port-Harcourt(4.20°N,7.00°E), and Nsukka (6.90°N,7.67°E)) in Nigeria are presented. Two years (Jan., 2011–Dec., 2012) archived data as provided by Tropospheric Data Acquisition Network (TRODAN) of the Centre for Atmospheric Research Anyigba, Kogi State were utilized for the study. Results showed that the values of surface refractivity (Ns) were low during the dry season months and high during the wet season months and also there was high value of NS at the coastal areas compared with the inland areas. It was also deduced that the mean value of NS for Abuja, Akure, Jos, Lagos, Markurdi, Nsukka and Port-Harcourt is 355, 362, 303, 391, 375, 361 and 399 N-units respectively. Results showed that the Radio Horizon Distance (RDH) values were generally low during the wet season months and high during the dry season months. The variability of radio horizon distance of transmitting antennas is higher in the Northern part of Nigeria than the southern part.

scholarly journals Coupling between the atmospheric circulation and extremes of the mass balance of Storglaciären, northern Scandinavia

1997 ◽  
Vol 24 ◽  
pp. 229-233 ◽  
Author(s):  
Veijo Allan Pohjola ◽  
Jeffrey C. Rogers
Keyword(s):  
Mass Balance ◽  
Atmospheric Circulation ◽  
Extreme Events ◽  
Air Flow ◽  
Synoptic Situation ◽  
Glacier Mass Balance ◽  
Data Set ◽  
Continuous Mass ◽  
The Mean

A large amount of glacier mass-balance data has been gathered during the last few decades. One of the ultimate goals with these data is to reveal changes in climate, recorded by the sensitive climatic gauges that glaciers are. How can we use the collected mass-balance data to retrieve knowledge of changes in climate and in the atmospheric circulation? One method is to examine the extremes of the summer and winter balance years from a glacier or a glaciated area, and from these reconstruct the mean synoptic situation for those years. We focus here on the long 50 year continuous mass-balance record from Storglaciären, northern Scandinavia, and analyze the extreme events in the data set. The results show that high net balance is favoured by stronger westerly air flow (more maritime influence) which increases accumulation in winter but reduces ablation in summer.

scholarly journals Coupling between the atmospheric circulation and extremes of the mass balance of Storglaciären, northern Scandinavia

1997 ◽  
Vol 24 ◽  
pp. 229-233 ◽  
Author(s):  
Veijo Allan Pohjola ◽  
Jeffrey C. Rogers
Keyword(s):  
Mass Balance ◽  
Atmospheric Circulation ◽  
Extreme Events ◽  
Air Flow ◽  
Synoptic Situation ◽  
Glacier Mass Balance ◽  
Data Set ◽  
Continuous Mass ◽  
The Mean

A large amount of glacier mass-balance data has been gathered during the last few decades. One of the ultimate goals with these data is to reveal changes in climate, recorded by the sensitive climatic gauges that glaciers are. How can we use the collected mass-balance data to retrieve knowledge of changes in climate and in the atmospheric circulation? One method is to examine the extremes of the summer and winter balance years from a glacier or a glaciated area, and from these reconstruct the mean synoptic situation for those years. We focus here on the long 50 year continuous mass-balance record from Storglaciären, northern Scandinavia, and analyze the extreme events in the data set. The results show that high net balance is favoured by stronger westerly air flow (more maritime influence) which increases accumulation in winter but reduces ablation in summer.

scholarly journals Simulation and Interpretation of the Genesis of Tropical Storm Gert (2005) as Part of the NASA Tropical Cloud Systems and Processes Experiment

2010 ◽  
Vol 67 (4) ◽  
pp. 999-1025 ◽  
Author(s):  
Scott A. Braun ◽  
Michael T. Montgomery ◽  
Kevin J. Mallen ◽  
Paul D. Reasor
Keyword(s):  
Sea Level ◽  
Tropical Storm ◽  
Sea Level Pressure ◽  
Cloud Systems ◽  
Low Level ◽  
Level Pressure ◽  
Stratiform Region ◽  
Stratiform Precipitation ◽  
Precipitation Processes ◽  
The Mean

Abstract Several hypotheses have been put forward for the mechanisms of generation of surface circulation associated with tropical cyclones. This paper examines high-resolution simulations of Tropical Storm Gert (2005), which formed in the Gulf of Mexico during NASA’s Tropical Cloud Systems and Processes Experiment, to investigate the development of low-level circulation and its relationship to the precipitation evolution. Two simulations are examined: one that better matches available observations but underpredicts the storm’s minimum sea level pressure and a second one that somewhat overintensifies the storm but provides a set of simulations that encapsulates the overall genesis and development characteristics of the observed storm. The roles of convective and stratiform precipitation processes within the mesoscale precipitation systems that formed Gert are discussed. During 21–25 July, two episodes of convective system development occurred. In each, precipitation system evolution was characterized by intense and deep convective upward motions followed by increasing stratiform-type vertical motions (upper-level ascent, low-level descent). Potential vorticity (PV) in convective regions was strongest at low levels while stratiform-region PV was strongest at midlevels, suggesting that convective processes acted to spin up lower levels prior to the spinup of middle levels by stratiform processes. Intense vortical hot towers (VHTs) were prominent features of the low-level cyclonic vorticity field. The most prominent PV anomalies persisted more than 6 h and were often associated with localized minima in the sea level pressure field. A gradual aggregation of the cyclonic PV occurred as existing VHTs near the center continually merged with new VHTs, gradually increasing the mean vorticity near the center. Nearly concurrently with this VHT-induced development, stratiform precipitation processes strongly enhanced the mean inflow and convergence at middle levels, rapidly increasing the midlevel vorticity. However, the stratiform vertical motion profile is such that while it increases midlevel vorticity, it decreases vorticity near the surface as a result of low-level divergence. Consequently, the results suggest that while stratiform precipitation regions may significantly increase cyclonic circulation at midlevels, convective vortex enhancement at low to midlevels is likely necessary for genesis.

Extreme convection in the Lofoten Basin of the Norwegian Sea

2021 ◽  
Author(s):  
Aleksandr M. Fedorov ◽  
Roshin P. Raj ◽  
Tatyana V. Belonenko ◽  
Elena V. Novoselova ◽  
Igor L. Bashmachnikov ◽  
...  
Keyword(s):  
Heat Release ◽  
Global Climate ◽  
Mixed Layer Depth ◽  
Water Volume ◽  
Convection Current ◽  
Mixing Depth ◽  
Sea Level Pressure ◽  
Factors Affecting ◽  
Strong Convection ◽  
Composite Maps

<p>One of the factors affecting the variability of the global climate is strong oceanic convection. Current research declares the results of the investigation on the extreme convection in the Lofoten Basin (LB) using the Argo profilers data. The most common parameter reflecting the convection intensity is Mixed Layer Depth (MLD). In the frames of the understudied period, MLD exceeds 1000 m in March-April and December 2010 in the Lofoten Basin Eddy (LBE), whereas the average MLD is about 200 m and rarely exceeds 400 m in the basin. Water volume formed at mid-depth of the central LB, between 1000 m depth and the isosteric surface s07 is connected with the extreme convection events. We analytically assess the final mixing depth that corresponds well to measured values of the MLD. Such a correspondence indicates the variations in the buoyancy flux and stratification as the main reasons for MLD variability in the LB. We easily explain this variability due to heat release in the basin. Atmospheric patterns during the extreme convection are described. It occurs that northerly winds are as common as dominating south-westerly winds during the months with extreme convection. 32 cases of extreme convective events with MLD exceeding 350 m were analyzed and we reveal that correspondent composite maps of Sea Level Pressure (SLP) and surface heat flux match well NAO-/EAP- atmospheric pattern in the Northern Atlantic, while negative NAO pattern prevails in climate during winter-spring. We define the heat release as the major trigger of strong convection. Heat release associated with extreme convection events in the LB is twice stronger than usual.</p>

VII.—The Dynamics of Cyclones and Anticyclones. Part III

1916 ◽  
Vol 36 (1-2) ◽  
pp. 174-185
Author(s):  
John Aitken
Keyword(s):  
Water Vapour ◽  
Atmospheric Circulation ◽  
Moist Air ◽  
The Earth ◽  
Isothermal Layer ◽  
New Knowledge ◽  
The Mean

In 1900 I communicated to this Society a paper on the above subject. Since that date a great deal of information has been obtained by means of free balloons carrying instruments which recorded the temperature, humidity, and pressure of the air up to great elevations. Much of this new knowledge seems to contradict our previous ideas, and does not seem to fit into the old convectional theory that cyclones are formed by the rising of the hot, moist air from the surface of the earth; their energy being due to their temperature and to the heat liberated by the condensation of the water vapour in them. We are told by those who have studied the bearing of the new knowledge on our atmospheric circulation that the old theory is “utterly untenable.” Their reasons for this conclusion are, first, that the recent investigations show that the air is colder in cyclones than in anticyclones; second, that the isothermal layer is lower than the mean over cyclones, while it is higher than the mean over anticyclones. At first sight these discoveries seem to shatter the convectional theory, but before we come to any conclusion I should like to present certain facts which it appears to me will require to be considered before we scrap our old ideas.

scholarly journals Response of a global atmospheric circulation model to spatio-temporal stochastic forcing: ensemble statistics

2003 ◽  
Vol 10 (6) ◽  
pp. 453-461 ◽  
Author(s):  
V. Pérez-Muñuzuri ◽  
M. N. Lorenzo ◽  
P. Montero ◽  
K. Fraedrich ◽  
E. Kirk ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Circulation Model ◽  
Ensemble Forecast ◽  
Forecast Evaluation ◽  
Correlated Noise ◽  
Stochastic Forcing ◽  
Statistical Measures ◽  
Ensemble Statistics ◽  
Spatio Temporal ◽  
Global Atmospheric Circulation

Abstract. The response of a simplified global atmospheric circulation model (PUMA) to spatiotemporal stochastic forcing is analyzed using the statistical measures originally developed for ensemble forecast evaluation. The nontrivial effects of time and length correlations of the stochastic forcing on the ensemble scores (e.g. spread and 'error') are studied. A maximum for these scores is observed to occur for specific values of the correlation time. The effects of multiplicative and additive contributions of the correlated noise are analyzed in terms of the noise and PUMA parameters.

scholarly journals Anomalies of Central England Temperature Classified by Air Source

2009 ◽  
Vol 22 (5) ◽  
pp. 1069-1081 ◽  
Author(s):  
David E. Parker
Keyword(s):  
Atmospheric Circulation ◽  
Late Nineteenth Century ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Source Regions ◽  
Central England Temperature ◽  
Long Term Changes ◽  
Late Nineteenth ◽  
Circulation Changes

Abstract Daily anomalies of mean central England temperature (CET), relative to daily 1961–90 climatology, are analyzed in terms of the source of the air estimated from fields of mean sea level pressure. The average CET anomaly for a given source and calendar month during 1961–90 is taken as an estimate of the influence of atmospheric circulation for that source and calendar month, and the uncertainty in this influence is provided by the associated standard error. The atmospheric circulation influences are subtracted from the daily CET anomalies since the late nineteenth century to yield “residual anomalies,” which represent the influence of forcings other than atmospheric circulation. The use of air sources captures more circulation-related daily CET variance than the airflow indices used in previous studies. The warming in central England since the 1970s is not predominantly a result of atmospheric circulation changes, and the long-term changes of CET for air from major source regions are on the whole very similar to each other and to the overall long-term changes.

Developing a Meaningful Understanding of the Mean

2003 ◽  
Vol 9 (1) ◽  
pp. 22-26
Author(s):  
Elizabeth George Bremigan
Keyword(s):  
Arithmetic Mean ◽  
Statistical Concept ◽  
Statistical Measures ◽  
The Mean

One of the first statistical measures that students encounter in their study of mathematics is the arithmetic mean. The procedure for determining the arithmetic mean of a given set of numbers is relatively simple, because it requires only two computational skills: addition and division. Thus, students are often introduced to the arithmetic mean in grades 4 or 5. At this level, computation of the arithmetic mean is frequently presented as an application of division rather than as a statistical concept. Initially, the arithmetic mean is often called the average; in this article, the arithmetic mean will be referred to simply as the mean.

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