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991.
Sarita Gajbhiye Chandrashekhar Meshram Rasoul Mirabbasi S. K. Sharma 《Theoretical and Applied Climatology》2016,123(3-4):593-617
The main goal of this paper is to estimate a set of optimal seasonal, daily, and hourly values of atmospheric turbidity and surface radiative parameters Ångström’s turbidity coefficient (β), Ångström’s wavelength exponent (α), aerosol single scattering albedo (ωo), forward scatterance (Fc) and average surface albedo (ρg), using the Brute Force multidimensional minimization method to minimize the difference between measured and simulated solar irradiance components, expressed as cost functions. In order to simulate the components of short-wave solar irradiance (direct, diffuse and global) for clear sky conditions, incidents on a horizontal surface in the Metropolitan Area of Rio de Janeiro (MARJ), Brazil (22° 51′ 27″ S, 43° 13′ 58″ W), we use two parameterized broadband solar irradiance models, called CPCR2 and Iqbal C, based on synoptic information. The meteorological variables such as precipitable water (uw) and ozone concentration (uo) required by the broadband solar models were obtained from moderate-resolution imaging spectroradiometer (MODIS) sensor on Terra and Aqua NASA platforms. For the implementation and validation processes, we use global and diffuse solar irradiance data measured by the radiometric platform of LabMiM, located in the north area of the MARJ. The data were measured between the years 2010 and 2012 at 1-min intervals. The performance of solar irradiance models using optimal parameters was evaluated with several quantitative statistical indicators and a subset of measured solar irradiance data. Some daily results for Ångström’s wavelength exponent α were compared with Ångström’s parameter (440–870 nm) values obtained by aerosol robotic network (AERONET) for 11 days, showing an acceptable level of agreement. Results for Ångström’s turbidity coefficient β, associated with the amount of aerosols in the atmosphere, show a seasonal pattern according with increased precipitation during summer months (December–February) in the MARJ. 相似文献
992.
The present experimental investigations study the effect of layering over rigid base on the dynamic behavior of foundation under vertical mode of vibration. Model block vibration tests were conducted on a rigid surface footing resting on different layered soil systems underlain by rigid base. The rigid base was used to simulate the presence of bedrock. The tests were carried out in a pit of size 2.0?m?×?2.0?m?×?1.9?m (deep) using a concrete footing of size 0.4?m?×?0.4?m?×?0.1?m. A rotating mass type mechanical oscillator was used for inducing vibration in vertical direction. Different layered soil systems were prepared within the total depth of 1,200?mm over the rigid base. Locally available gravel and fly ash were used to form different layered soil systems. In total, 132 nos. model block vibration tests in vertical mode were conducted for different layering and loading combinations. The experimentally obtained results are also compared with the results obtained from the analysis by mass-spring-dashpot and equivalent half-space theory. 相似文献
993.
994.
Mass sinking associated with soil creep and debris displacement is mainly responsible for landslide in Sunil area of Joshimath hill complex. Seepage plays the important role in soil subsidence. The area representing moderate to high relief denudational hills, shows rarely any insitu rock exposures. Gneissic boulders are embedded in loose sandy soil where due to presence of many springs excess seepage occurs, causing a soil creep and displacement of the bou.ders giving rise to local sinking. 相似文献
995.
A. G. Iosifidi A. N. Khramov A. A. Sadykova G. V. Trapeznikova S. K. Pukhonto 《Izvestiya Physics of the Solid Earth》2007,43(10):868-879
Collections of Early Triassic rocks sampled from three outcrops on the SW slope of the Pai-Khoi Ridge are studied. The magnetic polarity succession r-n-r is established from the prefolding characteristic component of natural remanence in sedimentary rocks and a basaltic nappe. According to stratigraphic data and isotopic dating of the basaltic nappe, the studied parts of the lower subformation of the Lestanshorskaya Formation correlate with the central part of magnetic zone R 1 T 1 of the European Russia magnetostratigraphic time scale. The angles of rotation in the horizontal plane are estimated for the studied Early Triassic Pai-Khoi structures with respect to the East European platform. 相似文献
996.
A study of the seasonal migration of ITCZ and the quasi-periodic oscillations in a simple monsoon system using an energy balance model 总被引:1,自引:0,他引:1
Summary A zonally averaged global energy balance model with feedback mechanisms was constructed to simulate (i) the poleward limits of ITCZ over the continent and over the ocean and (ii) a simple monsoon system as a result of differential heating between the continent and the ocean. Three numerical experiments were performed with lower boundary as (1) global continent, (2) global ocean and (3) continent-ocean, with freezing latitudes near the poles. Over the continent, midlatitude deserts were found and the ITCZ migrates 25° north and south with seasons. Over a global swamp ocean results do not show migration of ITCZ with time but once the ocean currents are introduced the ITCZ migrates 5° north and south with seasons. It was found that the seasonal migration of ITCZ strongly depends on the meridional distribution of the surface temperature. It was also found that continent influences the location of the oceanic ITCZ. In the tropics northward progression of quasi-periodic oscillations called events are found during the pre- and post-monsoon periods with a period of 8 to 15 days. This result is consistent with the observed quasi-periodic oscillations in the tropical region. Northward propagation of the surface temperature perturbation appears to cause changes in the sensible heat flux which in turn causes perturbations in vertical velocity and latent heat flux fields.List of Symbols
vertical average
- 0
zonal average
-
vertical mean of the zonal average
- 0s
zonal average at the surface
- 0a
zonal average at 500 mb level
-
latitude
We now define the various symbols used in the model
rate of atmospheric heating due to convective cloud formation (K/sec)
-
dp/dt (N/m2/sec)
-
density
-
potential temperature (K)
-
rate of rotation of the earth (rad/sec)
-
empirical constant
-
humidity mixing ratio
- *
saturated humidity mixing ratio
-
opacity of the atmosphere
- 1,2
factors for downward and upward effective black body long wave radiation from the atmosphere
-
Stefan-Boltzmann constant
-
emissivity of the surface
-
D
subsurface temperature (K)
-
a
specific volume
- 0xs
,0ys
eastward and northward components of surface frictional stress
- *
vertical velocity at the top of the boundary layer (N/m2/sec)
- P
Thickness of the boundary layer (mb)
-
nondimensional function of pressure
-
P
pressure
-
P
a
pressure of the model atmosphere (N/m2)
-
P
s
pressure at the surface (N/m2)
-
t
time (sec)
-
U
eastward wind speed (m/sec)
-
V
northward wind speed (m/sec)
-
surface water availability
-
T
absolute temperature (K)
-
heat addition due to water phase changes
-
g
acceleration due to gravity (m2/sec)
-
a
radius of the earth (m)
-
R
gas constant for dry air (J/Kg/K)
-
C
p
specific heat of air at constant pressure (J/Kg/K)
-
k
R/C
p
-
L
latent heat of condensation (J/Kg)
-
f
coriolis parameter (rad/sec)
-
H
s
H
0s
(1)
+H
0s
(2)
+H
0s
(3)
+H
0s
(4)
+H
0s
(5)
(J/m2/Sec)=sum of the rates of vertical heat fluxes per unit surface area, directed toward the surface
-
H
a
H
0a
(1)
+H
0a
(2)
+H
0a
(3)
+H
0a
(4)
(J/m2/Sec)=sum of the rates of heat additions to the atmospheric column per unit horizontal area by all processes
-
H
0s
(1)
,H
0a
(1)
heat flux due to short wave radiation
-
H
0s
(2)
,H
0a
(2)
heat flux due to long wave radiation
-
H
0s
(3)
,H
0a
(3)
heat flux due to small scale convection
-
H
0s
(4)
heat flux due to evaporation
-
H
0a
(4)
heat flux due to condensation
-
H
0s
(5)
heat flux due to subsurface conduction and convection
-
e
*
saturation vapor pressure
-
R
solar constant (W/m2)
-
r
a
albedo of the atmosphere
-
r
s
albedo of the surface
-
b
2
empirical constant (J/m2/sec)
-
c
2
empirical constant (J/m2/sec)
-
e
2
nondimensional empirical constant
-
f
2
empirical constant (J/m2/sec)
-
factor proportional to the conductive capacity of the surface medium
-
a
s
constant used in Sellers model
-
b
s
positive constant of proportionality used in the Sellers model (kg m2/J/sec2)
-
K
HT
coefficient for eddy diffusivity of heat (m2/sec)
-
K
HE
exchange coefficient for water vapor (m2/sec)
-
h
depth of the water column (m)
-
z
height (m)
-
V
0ws
meridional component of surface current (m/sec)
-
n
cloud amount
-
G
0,n
long wave radiation form the atmosphere for cloud amount n (W/m2)
-
B
0
long wave radiation from the surface (W/m2)
-
S
0,n
short wave radiation from the atmosphere for cloud amount n (W/m2)
-
A
n
albedo factor for a cloud amount n
-
R
f1
large scale rainfall (mm/day)
-
R
f2
small scale rainfall (mm/day)
With 22 Figures 相似文献
997.
R.K.R. Vupputuri 《大气与海洋》2013,51(4):728-738
Abstract A 2‐D time‐dependent Eulerian model that takes into account the major interaction between chemistry and dynamical transports in the stratosphere is used to simulate, in a self‐consistent manner, the anomalous spring variations of ozone, temperature and other relevant minor constituents in the southern polar region. The normal transport coefficients and the standard chemistry have been altered to represent the anomalous dynamical and chemical conditions in the extremely cold lower stratosphere of Southern Hemisphere (south of 65° S) spring. The results show that it is necessary to invoke both dynamical and chemical mechanisms in order to explain the observed rapid spring decline of total ozone in the southern polar region. 相似文献
998.
Global sea-level pressure distribution has been analysed for the months of April and July for 5 years of contrasting situations of Indian summer monsoon, comprising of two drought years (1972 and 1974), a flood year (1975) and two normal monsoon years (1970 and 1973). Mean monthly sea-level pressure data at about 400 stations have been used in the study. Prominent features of pressure departures from long-term normals have also been noted. It is observed that the month of April shows more prominent contrasting features than July. In April, the high pressure centres over USSR and the North Pacific move considerably eastward during poor monsoon years, while a breakaway cell of Icelandic Low goes deep south. Both the high pressure areas over south Indian Ocean and Australia are stronger in good monsoon years. In July, the subtropical high pressure zone over the southern Indian Ocean is stronger and the Australian high is more eastward, in good monsoon years. 相似文献
999.
Elmar K. Jessberger 《Meteoritics & planetary science》1988,23(3):233-234
Abstract— 40Ar-39Ar dating of a strongly shocked, vesiculated gneiss clast in a breccia from the Haughton impact structure yields an isochron age of 23.4 ± 1.0 Ma. The sample contains excess 40Ar. 相似文献
1000.
Prof. Dr. K. Metz 《International Journal of Earth Sciences》1962,52(1):210-226
Zusammenfassung Die Niederen Tauern sind ein Teil der großen Masse des ostalpinen Altkristallins. Zwei ihrer Anteile haben in altalpidischer Zeit durchaus verschiedenartige tektonische Prägungen erlitten: Die Gesteine der Seckauer Tauern unterlagen damals einer intensiven Teilbewegung im Gefüge und überdies einer Metamorphose, deren Typus als Seckauer Kristallisation durchaus der Tauern-Kristallisation der Hohen Tauern vergleichbar ist. Die westlich benachbarten Wölzer Tauern erfuhren zu gleicher Zeit lediglich eine starke Deformation, aber keine Metamorphose.Eingefaltete und mit den kristallinen Gesteinen geschuppte triadische Sedimente ermöglichen zusammen mit dem Auftreten von Jungtertiär eine zeitliche Unterteilung alpidischer Prägungsakte. In diesem Zusammenhang werden 2 Systeme tertiärer Bruchstörungen kurz beschrieben.Im vortertiären alpidischen Orogen waren die hier behandelten Kristallinmassen Angehörige von drei verschiedenen tektonischen Stockwerken: das tiefste mit einer starken alpidischen Metamorphose, darüber ein Stockwerk mit Faltungs- und Überschiebungstektonik und schließlich im Süden (Zirbitz-Sau- u. Koralm) ein oberstes Stockwerk mit Bruchtektonik unter Erhaltung aller voralpidischen Strukturelemente.Dieser Befund ist schlecht in Übereinstimmung zu bringen mit einer Auffassung, welche dieses Altkristallin lediglich als eingeschobene Riesenmasse kristalliner Gesteine ohne Differenzierung gegenüber dem tektonischen Geschehen betrachtet.
The Niedere Tauern as a part of the big mass of the ostalpines Altkristallin can be subdivided in various sections. Two of them show very different tectonic development during the pretertiary alpidic tectogenesis: In the Seckauer Tauern (gneisses and granites of various types) a rock deformation of high intensity took place and the rocks were metamorphosed in a specific type (Seckau crystallisation, comparable with the Tauern crystallisation of the Hohe Tauern). In the neighboured Wölzer Tauern at the same time only cinematic deformation without metamorphism was induced in the ancient mica schists.The presence of triassic sediments, infolded and imbricated in the cristalline series, as well as coal bearing tertiary sediments allow a chronological subdivision of the alpidic movements. Two arcs of tertiary fault-systems are described.The cristalline masses considered here were representing three different levels of the ancient-alpidic (pretertiary) Orogen: a deepest level with metamorphism and local gneissification, a level of folding and thrusting without metamorphism, a superficial level of ancient crystallins (Zirbitzkogel) with movements en bloc and complete preservation of all pre-alpidic rock features.Hence the author concludes that the eastalpine mass of cristallins, considered in the paper, was not a giant overthrusted nappe of uniform level, undifferentiated in respect to the eastalpine orogen.
Résumé Le massif des Niedere Tauern constitue une partie de la grande masse du vieux socle cristallin des Alpes orientales. Deux de leur parties ont subi des empreintes tectoniques différentes à la période la plus ancienne de la formation des Alpes: Les roches des Tauern de Seckau ont été soumises à cette époque à un mouvement intensif et en plus à une métamorphose dont le type, sous le nom de «cristallisation de Seckau», est tout à fait comparable à la «cristallisation de Tauern» dans la région des Hohe Tauern. Les Wölzer Tauern, situées à l'Ouest, n'ont subi à la même époque qu'une forte déformation, mais pas de métamorphose.Des sédiments triassiques, plissés et charriés avec les roches cristallines, ont permis grâce à la présence des couches du Tertiaire supérieur d'établir une division chronologique des phases tectoniques alpines. A ce sujet deux systèmes de fractures tertiaires sont décrits par la suite.A l'orogène prétertiaire les masses cristallines en question ont fait partie de trois étages structuraux différents: à la base un étage à forte métamorphose alpine, au milieu un étage à tectonique caractérisée par des plissements et des charriages et enfin au Sud un étage supérieur à tectoniques à fractures radiales conservant tous les éléments de la structure préalpine.Ces constatations peuvent difficilement s'accorder avec la théorie qui considère ce vieux socle cristallin comme une grosse masse des roches cristallines implantée sans différenciation vis à vis des processus tectoniques.
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