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1.
The main goals of this work are climatological analysis of characteristics of vertical wind in the stratosphere and estimation of potential opportunities of its influence on stratospheric aerosol particles. High-altitude, temporal, and latitude dependences of zonal mean vertical wind velocity for the period of 1992?C2006 from the UKMO atmospheric general circulation model are analyzed. It is shown that monthly averaged amplitudes of the vertical wind are approximately ±5?mm/s, while annual averaged ones are ±1?mm/s. The upward wind can provide the vertical lifting against gravity for sufficiently large (up to 3?C5???m) aerosol particles with a density up to 1.0?C1.5?g/cm3 at stratospheric and mesospheric altitudes. The vertical wind, probably, is a substantial factor for particle motion up to altitudes of 30?C40?km and can change essentially the sedimentation velocities and the residence times of stratospheric aerosols. The structure of the averaged fields of vertical wind supposes the opportunity of formation of dynamically stable aerosol layers in the middle stratosphere. With the problem regarding the action of a permanent source of monodisperse particles near the stratopause taken as an example, it is shown that if the action of the averaged vertical component is taken into account along with the gravitational sedimentation and turbulent diffusion, the standard vertical profiles of the relative concentration of particles change cardinally. Estimations for the levitation heights for particles of different densities and sizes in the stratosphere under action of gravity and vertical wind pressure are presented. 相似文献
2.
Summary Seasonal variations of gravity wave characteristics are investigated using rawinsonde data observed at Pohang observatory,
Korea (36°2′N, 129°23′E) during the one-year period of 1998. Analysis is carried out for two atmospheric layers representing
the troposphere (2–9 km) and stratosphere (17–30 km). There exist clear seasonal variations in amplitudes of temperature and
wind perturbations and wave energy in the stratosphere, with their maxima in wintertime and minima in summertime. A strong
correlation is found between the wave activity and the strength of the jet stream, but there is no clear correlation between
the wave activity and the vertical gradient of static stability. The intrinsic frequency and vertical and horizontal wavelengths
of gravity waves in the stratosphere are 2f–3f, where f is the Coriolis parameter, and 2–3 km and 300–500 km, respectively. The intrinsic phase velocity directs westward in January
and northeastward in July. The vertical flux of the stratospheric zonal momentum is mostly negative except in summertime with
a maximum magnitude in January. Topography seems to be a major source of stratospheric gravity waves in wintertime. Convection
can be a source of gravity waves in summertime, but it is required to know convective sources at nearby stations, due to their
intermittency and locations relative to floating balloons. 相似文献
3.
N. O. Plaude E. A. Stulov I. P. Parshutkina E. V. Sosnikova N. A. Monakhova V. V. Yakhno 《Russian Meteorology and Hydrology》2012,37(1):21-27
The seasonal variations of the concentration of particles of different sizes in the atmospheric surface layer are studied
on the basis of the data of daily measurements of atmospheric aerosol characteristics in the town of Dolgoprudny (20 km from
the center of Moscow) carried out in 2006–2009. It is revealed that the steady variations of monthly mean aerosol concentration
are observed within the particle diameter interval of 0.02–1 μm. The annual course of concentration of these particles has
two maxima, in February-March and in September–October, and one minimum in June. The concentrations of particles with the
size of 0.01–0.02 μm defined by the general atmospheric background and the concentrations of particles of >1 μm associated
with the local sources do not have clearly pronounced seasonal variations. It is shown that the regularities of the annual
concentration variations of particles with the size of 0.02–1 μm are mainly explained by the sign and value of the lapse rate
in the layer up to 925 hPa that indicates the prevalence of the vertical mixing in the processes of aerosol scattering in
the surface layer as compared with the horizontal transfer. 相似文献
4.
Effects of Thermal Stability and Incoming Boundary-Layer Flow Characteristics on Wind-Turbine Wakes: A Wind-Tunnel Study 总被引:2,自引:1,他引:1
Wind-tunnel experiments were carried out to study turbulence statistics in the wake of a model wind turbine placed in a boundary-layer
flow under both neutral and stably stratified conditions. High-resolution velocity and temperature measurements, obtained
using a customized triple wire (cross-wire and cold wire) anemometer, were used to characterize the mean velocity, turbulence
intensity, turbulent fluxes, and spectra at different locations in the wake. The effect of the wake on the turbulence statistics
is found to extend as far as 20 rotor diameters downwind of the turbine. The velocity deficit has a nearly axisymmetric shape,
which can be approximated by a Gaussian distribution and a power-law decay with distance. This decay in the near-wake region
is found to be faster in the stable case. Turbulence intensity distribution is clearly non-axisymmetric due to the non-uniform
distribution of the incoming velocity in the boundary layer. In the neutral case, the maximum turbulence intensity is located
above the hub height, around the rotor tip location and at a distance of about 4–5.5 rotor diameters, which are common separations
between wind turbines in wind farms. The enhancement of turbulence intensity is associated with strong shear and turbulent
kinetic energy production in that region. In the stable case, the stronger shear in the incoming flow leads to a slightly
stronger and larger region of enhanced turbulence intensity, which extends between 3 and 6 rotor diameters downwind of the
turbine location. Power spectra of the streamwise and vertical velocities show a strong signature of the turbine blade tip
vortices at the top tip height up to a distance of about 1–2 rotor diameters. This spectral signature is stronger in the vertical
velocity component. At longer downwind distances, tip vortices are not evident and the von Kármán formulation agrees well
with the measured velocity spectra. 相似文献
5.
S. Yonemura S. Kawashima H. Matsueda Y. Sawa S. Inoue H. Tanimoto 《Theoretical and Applied Climatology》2008,92(1-2):47-58
Summary The application of principal components and cluster analysis to vertical ozone concentration profiles in Tsukuba, Japan, has
been explored. Average monthly profiles and profiles of the ratio between standard deviation and the absolute ozone concentration
(SDPR) of 1 km data were calculated from the original ozone concentration data. Mean (first) and gradient (second) components
explained more than 80% of the variation in both the 0–6 km tropospheric and 11–20 km troposphere–stratosphere (interspheric)
layers. The principal components analysis not only reproduced the expected inverse relationship between mean ozone concentration
and tropopause height (r
2 = 0.41) and that in the tropospheric layer this is larger in spring and summer, but also yielded new information as follows.
The larger gradient component score in summer for the interspheric layer points to the seasonal variation of the troposphere–stratosphere
exchange. The minimum SDPR was at about 3 km in the tropospheric layer and the maximum was at about 17 km in the interspheric
layer. The tropospheric SDPR mean component score was larger in summer, possibly reflecting the mixing of Pacific maritime
air masses with urban air masses. The cluster analysis of the monthly ozone profiles for the 1970s and 2000s revealed different
patterns for winter and summer. The month of May was part of the winter pattern in the 1970s but part of the summer pattern
during the 2000s. This statistically detected change likely reflects the influence of global warming. Thus, these two statistical
analysis techniques can be powerful tools for identifying features of ozone concentration profiles.
Authors’ addresses: S. Yonemura, S. Kawashima, S. Inoue, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai,
Tsukuba, Ibaraki 305-0031, Japan; H. Matsueda, Y. Sawa, Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki
305-0052, Japan; H. Tanimoto, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. 相似文献
6.
During the second Arctic Gas and Aerosol Sampling Program conducted in April 1986, we performed measurements of the optically absorbing carbonaceous component of the ambient aerosol from the NOAA WP-3D aircraft operating between sea level and 10 km altitude. We collected the aerosol of filters that were exposed for several hours; we also operated the aethalometer to measure the concentration of aerosol black carbon in real time. The filter analyses represent averages over the altitude range and time span during which the filter was collecting. The real-time results were sorted by altitude to calculate vertical profiles of black carbon concentration. Values typically ranged from 300 to 500 ng m–3 at lower altitudes, decreasing gradually to 25 to 100 ng m–3 at 8–10 km. Strong stratification at lower altitudes was frequently observed. The magnitude of these concentrations suggests that the sources are distant regions of considerable fuel consumption. The presence of this material in the tropospheric column and its probable deposition to the high-albedo surface may result in perturbations of the solar radiation balance. The concentrations measured at the highest altitudes may mean that particulate carbon and accompanying emissions for which it is a tracer are mixing into the stratosphere. 相似文献
7.
D. Narayana Rao H. R. Singh J. R. Kulkarni A. Y. Chandrika S. Vijaya Bhaskara Rao 《Meteorology and Atmospheric Physics》2000,73(1-2):55-59
Summary Mesosphere-Stratosphere-Troposphere (MST) Radar wind data for the period June through September 1996 have been examined to
study vertical variation of Madden-Jullian Oscillations in wind and eddy kinetic energy (eke) in the normal monsoon season.
The domain of analysis in the vertical is from 6 to 20 km with a height resolution of 150 m. Fast-Fourier-Transformation (FFT)
has been applied to zonal (u), meridional(v) components of wind to extract the Madden-Jullian oscillations and eke. There
are three dominant modes viz., 50–70, 30–40 and 10–20 day periodicity, which contain considerable fraction of energy and show
high degree of vertical variability. The peak amplitude of 50–70 day mode in u, 30–40 mode in v and eke were observed at 16–17 km
just below the tropopause level. The peak amplitudes of 30–40 day mode in u and 50–70 day mode in v were found in the height
region of 13–16 km. To understand the origin and propagation of these waves, wave energy is calculated. The wave energy is
higher at tropospheric heights than at lower stratospheric heights indicating that the origin of these waves is in the troposphere,
and a part of the energy leaks into the stratosphere.
Received September 17, 1998/Revised September 26, 1999 相似文献
8.
Measurements of concentration fluctuation intensity, intermittency factor, and integral time scale were made in a water channel
for a plume dispersing in a well-developed, rough surface, neutrally stable, boundary layer, and in grid-generated turbulence
with no mean velocity shear. The water-channel simulations apply to full-scale atmospheric plumes with very short averaging
times, on the order of 1–4 min, because plume meandering was suppressed by the water-channel side walls. High spatial and
temporal resolution vertical and crosswind profiles of fluctuations in the plume were obtained using a linescan camera laser-induced
dye tracer fluorescence technique. A semi-empirical algebraic mean velocity shear history model was developed to predict these
concentration statistics. This shear history concentration fluctuation model requires only a minimal set of parameters to
be known: atmospheric stability, surface roughness, vertical velocity profile, and vertical and crosswind plume spreads. The
universal shear history parameter used was the mean velocity shear normalized by surface friction velocity, plume travel time,
and local mean wind speed. The reference height at which this non-dimensional shear history was calculated was important,
because both the source and the receptor positions influence the history of particles passing through the receptor position. 相似文献
9.
In this study, previous evaluations of the monthly mean structure of the tropical lower stratosphere in reanalyzed datasets
are extended to include the period 1958–1978, when no satellite-based observations were available. It is shown that a large
discontinuity, in temperatures near the tropical tropopause, in the NCEP data occurred when the Tiros Operational Vertical
Sounder (TOVS) became operational. When only rawinsonde data were available, the tropopause temperatures in the NCEP dataset
are in better agreement with ERA data for TOVS period. Both NCEP and NASA reanalyses show similar deviations from the ERA
data in the TOVS renalyses show similar deviations from the ERA data in the TOVS period. There is also a stepwise change in
the lower stratospheric meridional velocity when the TOVS data were introduced into the NCEP reanalyses. This discontinuity
is such that in the 1958–1978 period, the annual cycle in zonal mean meridional velocity in the NCEP data resembles that of
the ERA data in the 1979–1993 period. The differences are shown to result from large changes in the local meridional flow
in the Indonesian region. The temporal consistency of the QBO is examined; it is shown that the NCEP assimilation system is
sensitive to the data available. There is a change in the zonally asymmetric structure of the zonal wind over time, presumably
related to the changes in input data and the inability of the model to represent the three-dimensional structure of the tropical
lower stratosphere. These results provide further evidence of the value of rawinsonde data in data assimilation systems as
well as the need to use satellite radiance data in an appropriate manner.
Received: 7 April 1997 / Accepted: 4 September 1998 相似文献
10.
I. P. Parshutkina E. V. Sosnikova N. P. Grishina E. A. Stulov N. O. Plaude N. A. Monakhova 《Russian Meteorology and Hydrology》2011,36(6):355-361
Daily measurements of atmospheric aerosol characteristics were carried out in Dolgoprudny (Moscow region) in June–August 2010.
The particle concentrations at 11 size gradations within the range of 0.01–10 μm and the concentrations of cloud condensation
nuclei active at water vapor supersaturation of 0.2–1% were determined. It is shown that the long anticyclonic conditions
and the burning of forests and peat bogs resulted in the increase in total aerosol concentration in surface air by more than
1.5 times and in concentrations of particles with the diameter of 0.1–1 μm and > 1 μm by 5 and 10 times, respectively. The
fire smoke mainly consisted of the particles with the size of 0.1–3 μm. The particles with the size of more than 5 μm were
not observed. The recurrent visibility decrease up to hundreds of meters was caused by the increase in the concentration of
particles with the diameter of more than 0.32μm in the air. During the smoke blanketing, the concentration of active condensation
nuclei in aerosol increased almost by 20 times that created an opportunity for watering of aerosol particles and formation
of the acid smog. 相似文献
11.
Summary An attempt has been made in this paper to examine different modes of oscillation in the wind field during different seasons
over Thiruvananthapuram (lat. 8.29° N, long. 76.59° E, located at the extreme southwest coast of India) based on daily upper
air observations for the period from January 1997 to December 1999. A power spectral analysis is carried out with the upper
air data of the station. The study shows that one and half cycle of Quasi–Biennial Oscillation (QBO) and the power spectra
of the meridional wind component exhibit peaks between the period of four days and seven days (corresponding frequency range
between 0.25 day−1 and 0.15 day−1) during all seasons. The seasonal variation of these large-scale oscillations over the station depends upon the background
mean zonal flow, which in turn closely related to the QBO structure.
The time sequence of power spectra shows that the disturbances with periods between four days and seven days dominantly prevail
in the upper troposphere and lower stratosphere throughout the year. The regimes of high power spectral intensity in this
period range are maintained in the levels where the mean zonal flow (westerly or easterly) weakens and changes with height.
The study establishes the fact that disturbances (mixed Rossby-gravity waves) acquire maximum power in the winter season whereas
the south-west monsoon exhibits minimum spectral intensity when spreading of energy over a frequency range takes place. 相似文献
12.
This study investigates the organised motion near the canopy-atmosphere interface of a moderately dense spruce forest in heterogeneous,
complex terrain. Wind direction is used to assess differences in topography and surface properties. Observations were obtained
at several heights above and within the canopy using sonic anemometers and fast-response gas analysers over the course of
several weeks. Analysed variables include the three-dimensional wind vector, the sonic temperature, and the concentration
of carbon dioxide. Wavelet analysis was used to extract the organised motion from time series and to derive its temporal scales.
Spectral Fourier analysis was deployed to compute power spectra and phase spectra. Profiles of temporal scales of ramp-like
coherent structures in the vertical and longitudinal wind components showed a reversed variation with height and were of similar
size within the canopy. Temporal scales of scalar fields were comparable to those of the longitudinal wind component suggesting
that the lateral scalar transport dominates. The existence of a – 1 power law in the longitudinal power spectra was confirmed
for a few cases only, with a majority showing a clear 5/3 decay. The variation of effective scales of organised motion in
the longitudinal velocity and temperature were found to vary with atmospheric stability, suggesting that both Kelvin-Helmholtz
instabilities and attached eddies dominate the flow with increasing convectional forcing. The canopy mixing-layer analogy
was observed to be applicable for ramp-like coherent structures in the vertical wind component for selected wind directions
only. Departures from the prediction of m = Λ
w
L
s
−1 = 8–10 (where Λ
w
is the streamwise spacing of coherent structures in the vertical wind w and L
s
is a canopy shear length scale) were caused by smaller shear length scales associated with large-scale changes in the terrain
as well as the vertical structure of the canopy. The occurrence of linear gravity waves was related to a rise in local topography
and can therefore be referred to as mountain-type gravity waves. Temporal scales of wave motion and ramp-like coherent structures
were observed to be comparable. 相似文献
13.
Summary The importance of horizontal and vertical advection of temperature for the Antarctic major stratospheric warming in September
2002 has been investigated, by applying the thermodynamic energy equation to ECMWF temperature and wind data. The analysis,
which is carried out for the one-week period 19–26 September, shows that the large temperature increase in this period in
the polar stratosphere is mainly due to horizontal advection of temperature. In addition, it has been investigated to what
extent the observed temperature increase, as well as the change in the zonal wind, can be simulated with a simple conceptual
model of a moving polar vortex. The model consists of a horizontal, circular vortex whose centre moves with constant meridional
velocity off from the South Pole. The temperature and zonal wind fields are prescribed, stationary and zonally symmetric (relative
to the vortex centre). Despite its simplicity, the model simulates several important aspects of the observations, such as
the zonal-mean temperature increase and zonal-mean zonal wind reversal poleward of 60° S, and the zonal-mean temperature decrease
at middle latitudes. 相似文献
14.
Reanalysis datasets potentially offer the opportunity to examine the tropical quasi-biennial oscillation (QBO) in greater
detail than in the past, including the associated meridional circulation and the links with other parts of the atmosphere.
For such studies to be useful, the QBO represented by the reanalyses should be realistic. In this work, the QBO in the ERA
and NCEP reanalyses is validated against rawinsonde observations from Singapore. Monthly mean data are used. In the lower
stratosphere (at 50 hPa and 30 hPa) the ERA QBO is reasonable, although the wind extrema in both phases are too weak and the
vertical shear and the temperature anomalies are too small. The NCEP QBO is weaker still. At 10 hPa neither reanalysis system
performs well, both systems failing to reproduce the westerlies, possibly because of the proximity of the upper boundary.
The Singapore wind is representative of the zonal means in the reanalyses. The weak wind extrema in the reanalyses would not
support a wave-mean flow interaction theory of the QBO, because a large portion of the gravity wave spectrum which would be
absorbed in reality would be transmitted beyond 10 hPa. The stronger shear zones captured in the ERA data are associated with
larger, more realistic temperature perturbations near 30 hPa. The northward velocities in the NCEP data show a more realistic
structure than in the ERA reanalysis, where they are dominated by a vertical “gridpoint wave” structure in the lowermost stratosphere.
Despite the shortcomings of the reanalyses, the high correlations of the wind at 30 hPa and 50 hPa with the observations at
Singapore mean that the reanalyses could potentially be used to examine the effects of the QBO away from the tropical stratosphere.
Future reanalyses need to take full account of the wind shears evident in the rawinsonde observations and use models with
an adequate resolution to capture these vertical scales.
Received: 23 June 1997/Accepted 17 December 1998 相似文献
15.
Milton J. Woods Robert J. Davy Christopher J. Russell Peter A. Coppin 《Boundary-Layer Meteorology》2011,141(1):93-116
Analytical expressions for the cross-spectrum of wind speed are developed for the stochastic simulation of wind power in south-eastern
Australia. The expressions are valid for heights above the ground in the range 40–80 m, site separations of 1–30 km, and frequencies
of (1/6)–3 cycles h−1. The influence of site separation distance is taken into account, as are variables that are defined for blocks of time. These
variables include the mean and standard deviation of wind speed and the mean wind direction. The parameters of the model equations
are determined by non-linear least-squares regression with cross-validation over 10 years of wind measurements from 84 towers
in south-eastern Australia. 相似文献
16.
Mixing depth structure and its evolution have been diagnosed from radar wind profiler data in the Chamonix and the Maurienne valleys (France) during summer 2003. The behaviour of refractive index structure parameter C
n
2
peaks coupled with the vertical velocity variance σ
w
2
was used to estimate the height of the mixed layer. Tethersonde vertical profiles were carried out to investigate the lower layers of the atmosphere in the range of approximately 400–500 m above ground level. The tethersonde device was especially useful to study the reversal of the valley wind system during the morning transition period. Specific features such as wind reversal and the convective mixed layer up to approximately the altitude of the surrounding mountains were documented. The wind reversal was observed to be much more sudden in the Maurienne valley than in the Chamonix valley 相似文献
17.
Richard B. Stothers 《Climatic change》2007,83(4):515-521
A chronology of stratospheric aerosol optical depth for the period 1671–1881 is derived from total lunar eclipse colors. It
is compared with available proxy time series for the same period and with more refined data for more recent years. Contrary
to previous speculations, the stratosphere from 1671 to 1881 seems to have been mostly undisturbed volcanically, with only
two or three eruptions having injected into it truly significant amounts of aerosol-producing and climate-altering sulfur
gases. It is confirmed that the full record for 1671–2000 shows a marked, though possibly quasiregular, ∼80 year periodicity
in stratospheric aerosol optical depth, which appears also in polar ice-core acidity records and in volcanic eruption frequencies. 相似文献
18.
Using the monthly mean NCEP/NCAR reanalysis dataset, the three-dimensional Eliassen-Palm (EP) fluxes of quasi-stationary wave
propagation in the lower stratosphere were computed for each month from November to March for the period from 1958 to 2007.
It is shown that the upward planetary wave propagation from the troposphere to the stratosphere generally occurs over the
northern Eurasia, while their weak downward propagation is observed in Labrador and southern Greenland regions in the lower
stratosphere. Interannual variations of the vertical EP fluxes also have the dipole-like spatial pattern with the opposite
anomalies in the West and East hemispheres which are most prominent in January–February. Significant differences in the interaction
of the zonal circulation of the stratosphere in the beginning of winter (November–December) and mid-to-late winter (January–March)
are revealed. Intensification of the planetary waves’ penetration into the stratosphere in December causes changes in the
stratospheric dynamics, creating the “preconditions” for the stratospheric warming appearances in January, but such a mechanism
is not detected in February. In the years with the cold polar vortex, the “stratospheric bridge” is formed with the strengthening
of the upward EP flux over the northern Eurasia and downward EP flux over the North Atlantic. 相似文献
19.
Both aerosol and rainwater samples were collected and analyzed for ionic species at a coastal site in Southeast Asia over
a period of 9 months (January–September 2006) covering different monsoons. In general, the occurrence and distribution of
ionic species showed a distinct seasonal variation in response to changes in air mass origins. Real-time physical characterization
of aerosol particles during rain events showed changes in particle number distributions which were used to assess particle
removal processes associated with precipitation, or scavenging. The mean scavenging coefficients for particles in the range
10–500 nm and 500–10 μm were 7.0 × 10−5 ± 2.8 × 10−5 s−1 and 1.9 × 10−4 ± 1.6 × 10−5 s−1, respectively. A critical analysis of the scavenging coefficients obtained from this study suggested that the wet removal
of aerosol particles was greatly influenced by rain intensity, and was particle size-dependent as well. The scavenging ratios,
another parameter used to characterize particle removal processes by precipitation, for NH4
+, Cl−, SO4
2−, and NO3
− were found to be higher than those of Na+, K+, and Ca2+ of oceanic and crustal origins. This enrichment implied that gaseous species NH3, HCl, and HNO3 could also be washed out readily. These additional sources of ions in precipitation presumably counter-balanced the dilution
effect caused by high total precipitation volume in the marine and tropical area. 相似文献
20.
B. I. Ogorodnikov 《Russian Meteorology and Hydrology》2011,36(9):613-623
A meteorological situation is under consideration during a dust storm observed on September 5–7, 1992 over the Ukraine and
Belarus territory contaminated by radionuclide products after the Chernobyl accident. The highest average wind speed in Chernobyl
and Pripyat was 10–12 m/s, wind gusts reached 20 m/s. It was found that the radioactive aerosol concentration in the zone
of alienation of the Chernobyl NPP increased by one or two orders of magnitude. The transfer of radioactive dust particles
to the Vilnius outskirts is recorded. 相似文献