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1.
This study examines shelter effect against the wind by using wind fence with various porosities and distance. The shelter
effect of wind fence was investigated by a wind tunnel test. Flow characteristics of velocities and turbulences behind wind
fence were measured using a hot-wire anemometer. This was done by varying the porosity by 0, 20, and 40% of the wind fence.
The wind fence distance ranged from 1H to 9H. In addition, the overall characterization of the wind fence was investigated by measuring a total of 28 points on the wind
fence, which forms a lattice structure on it with 7 points in the lateral direction and 4 points in the vertical direction.
The results indicate that the degree of the turbulence is lowered and the velocity of the wind is decreased when porosity
of 40% is used at a distance of 4H–7H. The effectiveness of the wind fence depends on the porosity and distance. Porosity of 20% proved to be effective for the
protection area of 1H–3H, while that of 40% was effective for the protection area of 4H–6H. 相似文献
2.
Using detailed measurements of the instantaneous velocity fields around fences with different heights and porosities, the pressure fields around the fences were calculated using the Reynolds equations. Based on the results of calculation, the relationships among the pressure field, fence porosity (i.e., the β coefficient), fence height, and free-stream wind velocity were examined. For all fences, a high-pressure region exists upwind of the fence, and a low-pressure region exists downwind of the fence, the change of mean pressure is gradually less to a long distance from the fence. The pressure value at the center of the low-pressure area downwind of the fence decreases with increasing fence height and free-stream wind velocity. The impact of the fence’s porosity on pressure is large, when β < 0.2, the mean pressure upwind of the fence is relatively small, and the center value of the low-pressure area downwind of the fence increases with increasing fence porosity; when β > 0.3, the mean pressure increases around the fence. 相似文献
3.
Feras Youssef Gunay Erpul Pieter Bogman Wim M. Cornelis Donald Gabriels 《Environmental Geology》2008,55(4):741-750
The trap efficiency of a catcher in wind erosion measurements plays a significant role, and in many cases suspension trap
efficiencies at high wind velocities are still unknown. The sediment trap efficiency generally changes with particles size
and with wind speed. In this study, the efficiency of Vaseline Slide (VS) and Modified Wilson and Cooke (MWAC) catchers were
determined with different sand particle sizes (<50, <75, 50–75, 200–400, and 400–500 μm) at a fixed wind speed (13.3 ms−1) and with different soil textures at different wind velocities (10.3, 12.3, and 14.3 ms−1) in the wind tunnel of the International Center for Eremology (ICE), Ghent University, Belgium. The traps were placed at
different heights (4, 6.5, 13, 20, 120, and 192 cm for VS and 1.5, 3, 5, 8, 11, and 30 cm for MWAC) to catch saltating and
suspended sediments in a 12-m long, 1.2-m wide and 3.2-m high working section of the wind tunnel. In the sand particle experiments,
the efficiency of the VS catcher was 92% for particles smaller than 50 μm and decreased with increasing particles size, falling
to 2.2% for 400–500 μm particle size at 13.4 ms−1. However, the MWAC’s efficiency was 0% for particles smaller than 50 μm and increased with increasing particle size to 69.5%
at 400–500 μm. In the experiments with different soil textures, the efficiency of each catcher significantly changed with
soil and with wind speed. It also considerably varied with the catchers: for instance, for sand (S), the MWAC efficiency was
very high (67.4, 113.4, and 90.5% at 10.3, 12.3, and 14.4 ms−1, respectively) while the efficiency of VS was relatively very low (5.2, 4.4, and 1.9% at 10.3, 12.3, and 14.4 ms−1, respectively). Results indicated that the efficiency depends critically on the particle size, type of catcher, and wind
speed, and these could be helpful to increase the robustness of wind erosion measurements. 相似文献
4.
Summary
Rock restraining net is a device engineered to stop large rockfalls. The system consists of a net vertically supported by
steel posts with “energy dissipators” able to dissipate high kinetic energy by large displacements. These fences have been
usually placed to protect against rockfalls in mountainous areas but few tests have been developed correctly to define the
behaviour of these structures. In this paper full scale tests on passive defence against rock falls are presented. The tests
have been carried out in a field test site especially designed and built. The test site has been provided of camera apparatus
able to monitor the impact of the block against the fence. The impact energy and the consequent forces and displacements of
the fence are studied. The tests have been carried out on many different fence types and have allowed the definition of a
well-established design procedure. 相似文献
5.
I. M. Gorokhov M. A. Semikhatov T. L. Turchenko P. Yu. Petrov N. N. Mel’nikov G. V. Konstantinova E. P. Kutyavin 《Stratigraphy and Geological Correlation》2010,18(5):480-491
Fine-grained clayey subfractions (SF) with particle sizes of 1–2, 0.6–1.0, 0.3–0.6, 0.2–0.3, 0.1–0.2, and <0.1 μm were extracted
from shales of the Vendian Staraya Rechka Formation in the Anabar Massif and studied by XRD and Rb-Sr methods. All the clayey
subfractions are represented by illite with high crystallinity indices, which are characteristic of the low-temperature diagenesis/catagenesis
zone and grow with the decrease of the particle size. The Rb-Sr systematics in clayey subfractions combined with mineralogical
data provide grounds for the conclusion that illite from clayey rocks of the Staraya Rechka Formation was forming during two
periods: approximately 560 and 391–413 Ma ago. The first illite generation was likely formed in the course of lithostatic
subsidence of the Staraya Rechka sediments and the second one, during the Devonian lithogenesis stage. It is assumed that
age of the first generation (∼560 Ma) is close to that of the Staraya Rechka Formation. This inference is consistent with
biostratigraphic, chemostratigraphic, and geochronological data obtained for both rocks of the Anabar Massif and Vendian sediments
from other regions of Siberia. 相似文献
6.
Rock and flow parameters of three karstic-fissured-porous aquifers in the Krakow-Silesian Triassic formations were measured
using various methods and compared. Though cavern and fissure porosities are shown to be very low (cavern porosity below 0.5%
and fracture porosity below 0.2%), they contribute dominantly to the hydraulic conductivity (from about 1.3×10–6 to about 11×10–6 m/s). Matrix porosity (2–11%) is shown to be the main water reservoir for solute transport and the main or significant contributor
to the specific yield (<2%). Though the matrix porosity is shown to be much larger than the sum of the cavern and fissure
porosities, its contribution to the total hydraulic conductivity is practically negligible (hydraulic conductivity of the
matrix is from about 5×10–11 m/s to about 2×10–8 m/s). On the other hand, the matrix porosity (for neglected cavern and fissure porosities) when combined with tracer ages
(or mean travel times) is shown to yield proper values of the hydraulic conductivity (K) by applying the following formula:
K≅(matrix porosity×mean travel distance)/(mean hydraulic gradient×mean tracer age). Confirming earlier findings of the authors,
this equation is shown to be of great practical importance because matrix porosity is easily measured in the laboratory on
rock samples, whereas cavern and fracture porosities usually remain unmeasurable.
Received: 21 February 1997 · Accepted: 13 May 1997 相似文献
7.
Effect of Random Inclusion of Polypropylene Fibers on Strength Characteristics of Cohesive Soil 总被引:2,自引:1,他引:1
Pradip Kumar Pradhan Rabindra Kumar Kar Ashutosh Naik 《Geotechnical and Geological Engineering》2012,30(1):15-25
This paper presents the effect of random inclusion of polypropylene fibers on strength characteristics of soil. Locally available
cohesive soil (CL) is used as medium and polypropylene fibers with three aspect ratios (l/d = 75, 100 and 125) are used as reinforcement. Soil is compacted with standard Proctor’s maximum density with low percentage
of reinforcement (0–1% by weight of oven-dried soil). Direct shear tests, unconfined compression tests and CBR tests were
conducted on un-reinforced as well as reinforced soil to investigate the strength characteristics of fiber-reinforced soil.
The test results reveal that the inclusion of randomly distributed polypropylene fibers in soil increases peak and residual
shear strength, unconfined compressive strength and CBR value of soil. It is noticed that the optimum fiber content for achieving
maximum strength is 0.4–0.8% of the weight of oven-dried soil for fiber aspect ratio of 100. 相似文献
8.
Death tolls from tornadoes in Bangladesh are the highest in the world due to lack of storm warnings, poor communication, weak
housing, and lack of shelters from strong winds in tornadoes and nor’westers. Based on surveys of housing types and designs
in the Tangail district, a household tornado shelter is proposed to be placed in the elevated storage platform that is common
in houses. The shelter is 2 m tall, 1.2 m wide, and 2–4 m long (4.8–9.6 m3 in volume) with the floor of the shelter placed one meter below the floor of the house. Walls are 7–10 cm thick and made
of concrete or an earthen wall stabilized with cement or strengthened with bamboo or bricks. A survey of 200 residents of
the region found nearly universal acceptance for the shelter design, and residents were eager for installation of the household
shelters. The shelter cost is 2,500–10,000 taka (US50 to50 to 200) depending on local material and labor costs but residents
were willing to pay an average of only 1,071 taka (US$21) toward the cost of the shelter. Families with greater income and
land holdings and families in villages with recent tornado experience were willing to spend more for a shelter. A pilot project
to install household tornado shelters in selected villages and monitor their use, along with continued efforts to issue storm
warnings, communicate the warnings, and improve education about storm hazards, will prevent injuries and save lives in Bangladesh
and reduce the descent into poverty that results from losses in severe local storms. 相似文献
9.
We examined the effect of nutrients and grazers on Thalassia testudinum in Jobos Bay, Puerto Rico by fertilizing sediment and manipulating grazer abundances. Bottom-up effects were variable: Added
nutrients did not increase seagrass aboveground biomass, but decreased belowground biomass—perhaps as a result of less biomass
being allocated to belowground structures in response to greater nutrient supply in porewater. Experimental fencing of 1.5 × 1.5 m
plots provided shelter that attracted large aggregations of fish, including seagrass herbivores. Seagrass biomass and shoot
density decreased with increasing abundance of herbivorous fish, indicating a significant top-down effect. There were interactions
between nutrient supply, provision of shelter, and grazing pressure. Fertilization enhanced seagrass %N; however, %N also
increased in unfertilized plots that were fenced, most likely due to uptake of N excreted from the large numbers of fish associated
with the fences. Only plots where shelter was provided and fertilizer was applied to sediments exhibited evidence of heavy
grazing, reducing both seagrass cover and aboveground biomass. In the unfertilized fenced plots, signs of grazing were fewer
despite large abundances of fish and enhanced nutritional quality of seagrass leaves. This suggests the possibility that high
nutrient availability in sediments lowered concentrations of chemical defense compounds in the seagrass and that cues other
than %N may have been involved in stimulating grazing. This study highlights the complexity of bottom-up and top-down interactions
in seagrass systems and the important role of refuge availability in shaping the relative strengths of these controls. 相似文献
10.
Rockfalls are major natural hazards in mountainous regions and as such monitored if they pose a high risk to people or infrastructure. Ground-based radar interferometry is a relatively new technique suitable for such monitoring. It offers the potential for determining sub-mm- to mm-level displacements by remote measurements under various weather conditions. To avoid damage from smaller rocks and debris, critical surfaces are often protected by rockfall catch fences. We present an experimental investigation proving that the radar measurements are indeed significantly affected by a catch fence made of steel even if its mesh size is larger compared to that of the wavelength of the radar. A stable rock wall in a quarry was monitored by means of a ground-based synthetic aperture radar for 2 days. Different fences varying in shape, size, and density of mesh and in various geometrical configurations were erected at different locations for short periods of time during the experiment. We show that for surfaces observed through the fence, the reflected power can be reduced by 20 dB and thus the signal-to-noise ratio is significantly deteriorated. We also observed spurious interferometric phase shifts. Even parts of the rock wall not covered by the fences are affected. Side lobes and mixed pixels result, e.g., in severe loss of coherence and thus potentially mask actual displacements. 相似文献
11.
Variations in long term wind speed during different decades in Arabian Sea and Bay of Bengal 总被引:1,自引:0,他引:1
A study has been carried out by comparing the extreme wind speeds estimated based on NCEP/NCAR reanalysis data for 100 years
return period using Fischer Tippet-1 (commonly known as Gumbel) and Weibull distributions for three locations (off Goa, Visakhapatnam
and Machilipatnam) in the north Indian Ocean. The wind dataset for Goa is compared with that from ERA-40 data. For higher
wind speeds (12–20m s−1), NCEP wind speed has higher percentage of occurrence than that of ERA-40. Analysis has shown slight upward trend in the
annual maximum wind for location off Machilipatnam with an increase of 1.2 cm s−1 per year and a decreasing trend of −1.3 cm s−1 per year in the case of Goa. The Weibull distribution with shape parameter 2 fits the annual maximum wind data better than
FT-1 distribution. 相似文献
12.
Nebkha development and its relationship to environmental change in the Alaxa Plateau,China 总被引:2,自引:0,他引:2
Xunming Wang Honglang Xiao Jinchang Li Mingrui Qiang Zhizu Su 《Environmental Geology》2008,56(2):359-365
Extensive nebkha areas develop mainly under the control of aeolian processes, and their sediments record information on regional
environmental changes during different periods. Such areas have developed on the dry riverbeds and deserted arable lands of
China’s Alaxa Plateau, Taklimakan, and Kumutage deserts. In this paper, we studied nebkhas that had developed in the Heicheng–Juyan
region to determine their CaCO3 contents, particle size distributions, and creation dates. Extensive human activities have occurred in this region since
at least in the late Tang Dynasty (618–907 ad). Although historical records show that most of the region’s rivers dried up around 1372, surface water persisted in some
areas until the early Qing Dynasty (1644–1911 ad). After the 1600s, extensive nebkhas began to develop due to drying of the region’s rivers. The early stages of nebkha development
were controlled by both the sediment supply and the regional wind regime, whereas late stages were controlled primarily by
variations in wind activity. In the Alaxa Plateau, it took about 100 years for arable lands and riverbeds to evolve into gobi
deserts, and during this time, several phases occurred with different levels of wind activity. The land degradation processes
in this region are mainly controlled by surface water resources, and the impact of human activities such as reclamation on
land degradation appear to have been overestimated in previous studies. 相似文献
13.
The ion composition of fluxes of charged particles in interplanetary space with energies ∼0.03–10 MeV/nucleon are studied
during quiet periods in the 23rd solar-activity cycle using data from the ACE spacecraft. Apart from the activity minimum,
the Fe/O ratio during such periods corresponds to either the relative abundances of ions in particle fluxes accelerated in
solar flares or the mean abundances of elements in the solar corona. At the cycle minimum, this ratio takes on values characteristic
for the solar wind. These results indicate that the background fluxes of low-energy particles in the phases of the growth,
maximum, and decay of the solar cycle include significant contributions from both coronal particles accelerated to suprathermal
energies and particles accelerated in small impulsive solar flares. The particle fluxes from such flares are distinguished
by an enhanced abundance of iron ions. 相似文献
14.
The suitability of the European Centre for Medium Range Weather Forecasting (ECMWF) operational wind analysis for the period
1980–1991 for studying interannual variability is examined. The changes in the model and the analysis procedure are shown
to give rise to a systematic and significant trend in the large scale circulation features. A new method of removing the systematic
errors at all levels is presented using multivariate EOF analysis. Objectively detrended analysis of the three-dimensional
wind field agrees well with independent Florida State University (FSU) wind analysis at the surface. It is shown that the
interannual variations in the detrended surface analysis agree well in amplitude as well as spatial patterns with those of
the FSU analysis. Therefore, the detrended analyses at other levels as well are expected to be useful for studies of variability
and predictability at interannual time scales. It is demonstrated that this trend in the wind field is due to the shift in
the climatologies from the period 1980–1985 to the period 1986–1991. 相似文献
15.
The stability analyses of the stream function at the upper atmosphere have been conducted using a global barotropic spectral
model with a view to examine the seasonal characteristics. The growing eigen modes are classified into three groups with periods
in the range of 3–8, 11–18 and 20–50 days. This study indicates that the growth and movement of all the three types of modes
are adequately sustained by the asymmetric basic flow. All the modes grow faster in summer than in winter. The meridional
shear of the basic flow is the most important source of growth of the perturbations. In the absence of the meridional wind
shear, the eigen modes grow slowly, in which case, the quasi-nonlinear triad interaction between the waves is identified to
contribute significantly to the growth of the modes. The robustness of the eigen modes is also examined in this study using
the barotropic model at different horizontal resolutions in the triangular truncation scheme. 相似文献
16.
Angelo Paone 《International Journal of Earth Sciences》2008,97(3):635-650
A compilation of B–Be–Li data on rocks that cover the entire eruptive history of Somma-Vesuvius is presented and interpreted
in the light of evolution models for the Somma-Vesuvius rocks. Using major and trace element data, fractional crystalllization
models are presented for different geochemical units. These data were used to constrain the source mineralogy of the Somma-Vesuvius
rocks (ol-opx-cpx-gar-amp of 0.4-0.3-0.1-0.1-0.1), the amount of sediment added (5–10%) and the melt fraction from batch partial
melting computations (0.05–0.1). From the B–Li data it is inferred that the main process responsible for the B isotopic signature
is sediment recycling. However, the B–Li data show a major variation in Li abundances respect to B which is explained with
Li dehydration before the fluid enriched the mantle wedge that produced the arc magmas. The Somma-Vesuvius B isotope composition
is intermediate between that of the Campi Flegrei and the broad field of the Eolian Island arc. A low Be isotopes in the recent
volcanic rocks can be explained as: (a) the top 1–22 m of the incoming sediment is accreted, (b) large amounts of sediment
erosion, (c) a slow rate of subduction which have provoked a long magmatic history for the Vesuvius magma, (d) the sediment
component takes several Myr longer than the subducting plate to reach the magma source region beneath Italy. 相似文献
17.
Diurnal soil water dynamics in the shallow vadose zone (field site of China University of Geosciences,China) 总被引:3,自引:0,他引:3
Yijian Zeng Li Wan Zhongbo Su Hirotaka Saito Kangle Huang Xusheng Wang 《Environmental Geology》2009,58(1):11-23
Because of the relatively low soil moisture in arid or semi-arid regions, water vapour movement often predominates in the
vadose zone and affects the partitioning of energy among various land surface fluxes. In an outdoor sand bunker experiment,
the soil water content at 10 and 30 cm depth were measured at hourly intervals for 2.5 days during October 2004. It was found
that the soil moisture reached the daily maximum value (5.9–6.1% at 10 cm and 11.9–13.1% at 30 cm) and minimum value (4.4–4.5%
at 10 cm and 10.4–10.8% at 30 cm) at midday (0–1 p.m. for 10 cm and 2–3 p.m. for 30 cm) and before dawn (2–3 a.m. for 10 cm
and 4–5 a.m. for 30 cm), respectively. The modified HYDRUS-1D code, which refers to the coupled water, water vapour and heat
transport in soil, was used to simulate the moisture and water vapour flow in the soil. The numerical analyses provided insight
into the diurnal movement of liquid water and water vapour driven by the gradients of pressure heads and temperatures in the
subsurface zone. The simulated temperature and water content were in good agreement with the measured values. The spatial–temporal
distribution of liquid water flux, water vapour flux and soil temperature showed a detailed diurnal pattern of soil water
dynamics in relatively coarse sand.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
Sensitivity experiments are conducted for three cases of cyclones for investigating the impact of different vortex initialization
schemes on the structure and track prediction of the cyclone using India Meteorological Department’s Limited Area Model. The
surface wind and pressure profiles generated using Holland and Rankine initialization schemes differ from each other. These
different generated profiles are compared with the actual data and the root mean square error (RMSE) was calculated between
them. In case of the Holland vortex, ‘b’ is found to be equal to 1.5 and 2.0 respectively for two cases of very severe cyclonic storms in the Arabian Sea, namely
6–10 June 1998 and 16–20 May 1999 and 2.25 for the severe cyclonic storm in the Bay of Bengal. The ‘α’ parameter in Rankine’s
scheme was found to be 0.5 for two cases and 0.4 for the third system. This shows that cyclones differ even if they attain
the same intensity. The values of these parameters i.e. ‘b’ and ‘α’ are used for generating the synthetic wind data for individual cyclones and the same is used in the data assimilation
system. The analysis and forecast generated for the above cases using the Holland scheme show that the simulated structure
has characteristics closer to the actual storm; however, the Rankine scheme shows a weaker circulation. The mean track error
for three cases in the Holland scheme is 93, 149, 257 and 307 km in 12-, 24-, 36- and 48-h forecast. The mean track errors
for the Rankine scheme are 152, 274, 345 and 327 km, respectively, for the same period. 相似文献
19.
Lucy E. McGee Christoph Beier Ian E. M. Smith Simon P. Turner 《Contributions to Mineralogy and Petrology》2011,162(3):547-563
The Auckland volcanic field is a Quaternary monogenetic basaltic field of 50 volcanoes. Rangitoto is the most recent of these
at ~500 year BP and may mark a change in the behaviour of the field as it is the largest by an order of magnitude and is unusual
in that it erupted magmas of alkalic then subalkalic basaltic composition in discrete events separated by ≤50 years. Major
and trace element geochemistry together with Sr–Nd and U-Th–Ra isotopes provides the basis for modelling the melting conditions
that brought about the eruption of two chemically different lavas with very little spatial or temporal change. Sr–Nd isotopes
suggest that the source for both eruptions is similar with a slight degree of heterogeneity. The basalts show high 230Th-excess compared with comparable continental volcanic fields. We show that the alkalic basalts give evidence for lower degrees
of partial melting, higher amounts of residual garnet, a longer melting column and lower melting and upwelling rates compared
with the subalkalic basalts. The low upwelling rates (0.1–1.5 cm/year) modelled for both magmas do not suggest a plume or
major upwelling in the mantle region beneath Auckland; therefore, we suggest localised convection due to relict movement from
the active subduction system situated 400 km to the southeast. A higher porosity for the initial alkalic basalt is based on
226Ra-excesses, suggesting movement of melt by two different porosities: the initial melt travelling in fast high porosity channels
from greater depths preserving a high 230Th-excess and the subsequent subalkalic magma travelling from a shallower depth through lower porosity diffuse channels preserving
a high 226Ra-excess; this creates a negative array in (226Ra/230Th) versus (230Th/238U) space previously only seen in mid ocean ridge Basalt data. This mechanism suggests the Auckland volcanic field may operate
by the presence of discrete melt batches that are able to move at different depths and speeds giving the field its erratic
spatial and temporal pattern of eruptions, a type of behaviour that may have implications for the evolution of other continental
volcanic fields worldwide. 相似文献
20.
The role of intraseasonal oscillations (ISOs) in modulating synoptic and interannual variations of surface winds over the
Indian monsoon region is studied using daily averaged National Centers for Environmental Prediction/National Centre for Atmospheric
Research (NCEP/NCAR) reanalyses for the period 1987–1996. Two dominant ISOs are found in all years, with a period between
30–60 days and 10–20 days respectively. Although the ISOs themselves explain only about 10–25% of the daily variance, the
spatial structure of variance of the ISOs is found to be nearly identical to that of high frequency activity (synoptic disturbances),
indicating a significant control by the ISOs in determining the synoptic variations. Zonal and meridional propagation characteristics
of the two modes and their interannual variability are studied in detail.
The synoptic structure of the 30–60 day mode is similar in all years and is shown to be intimately related to the strong (‘active’)
or weak (‘break’) phases of the Indian summer monsoon circulation. The peak (trough) phase of the mode in the north Bay of
Bengal corresponds to the ‘active’ (‘break’) phase of monsoon strengthening (weakening) the entire large scale monsoon circulation.
The ISOs modulate synoptic activity through the intensification or weakening of the large scale monsoon flow (monsoon trough).
The peak wind anomalies associated with these ISOs could be as large as 30% of the seasonal mean winds in many regions. The
vorticity pattern associated with the 30–60 day mode has a bi-modal meridional structure similar to the one associated with
the seasonal mean winds but with a smaller meridional scale. The spatial structure of the 30–60 day mode is consistent with
fluctuations of the tropical convergence zone (TCZ) between one continental and an equatorial Indian Ocean position. The 10–20
day mode has maximum amplitude in the north Bay of Bengal, where it is comparable to that of the 30–60 day mode. Elsewhere
in the Indian Ocean, this mode is almost always weaker than the 30–60 day mode. In the Bay of Bengal region, the wind curl
anomalies associated with the peak phases of the ISOs could be as large as 50% of the seasonal mean wind curl. Hence, ISOs
in this region could drive significant ISOs in the ocean and might influence the seasonal mean currents in the Bay.
On the interannual time scale, the NCEP/NCAR reanalysed wind stress is compared with the Florida State University monthly
mean stress. The seasonal mean stress as well as interannual standard deviation of monthly stress from the two analyses agree
well, indicating absence of any serious systematic bias in the NCEP/NCAR reanalysed winds. It is also found that the composite
structure of the 30–60 day mode is strikingly similar to the dominant mode of interannual variability of the seasonal mean
winds indicating a strong link between the ISOs and the seasonal mean. The ISO influences the seasonal mean and its interannual
variability either through increased/decreased residence time of the TCZ in the continental position or through occurrence
of stronger/weaker active/break spells. Thus, the ISOs seem to modulate all variability in this region from synoptic to interannual
scales. 相似文献