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1.
A numerical case study with a second-order turbulence closure model is proposed to study the role of urban canopy layer (UCL) for the formation of the nocturnal urban boundary layer (UBL). The turbulent diffusion coefficient was determined from an algebraic stress model. The concept of urban building surface area density is proposed to represent the UCL. Calculated results were also compared with field observation data. The height of the elevated inversion above an urban center was simulated and found to be approximately twice the average building height. The turbulent kinetic energy k, energy dissipation rate , and turbulence intensities u
2 and w
2 increase rapidly at the upwind edge of the urban area. The Reynolds stress uw displayed a nearly uniform profile inside the UBL, and the vertical sensible heat flux w had a negative value at the inversion base height. This indicates that the downward transport of sensible heat from the inversion base may play an important role in the formation of the nocturnal UBL. 相似文献
2.
P. A. Taylor 《Boundary-Layer Meteorology》1971,1(4):474-497
A numerical model of airflow above changes in surface roughness and thermal conditions is extended to include cases with stable thermal stratification within the internal boundary-layer. The model uses a mixing-length approach with empirical forms for M and H.Results are presented for some basic cases and an attempt is then made to compare results given by the model with the experimental results of Rider, Philip and Bradley. Tolerable agreement is achieved. The importance of roughness change and thermal stability effects in the diffusion of heat and moisture near a leading edge is emphasised.Notation A
Refers to Taylor (1970)
-
B
Businger-Dyer constant (= 16.0) in forms for
M
and
H
-
C
Constant in form for in stable case
-
c
p
Specific heat at constant pressure
-
E
Scaled absolute humidity
-
g
Acceleration due to gravity
-
H
Upward vertical heat flux
-
H
0, H
1
Surface heat fluxes for x <0, x0
-
H
E
Upward latent heat flux
-
k
Von Kármán's constant (= 0.4)
-
K
H
K
W
Eddy transfer coefficients for heat and water vapour
-
L
Monin-Obukhov length
-
L
H
Latent heat of evaporation for water
-
m
Ratio of roughness lengths ( = z
1/z
0)
- RPB
Refers to Rider et al. (1964)
-
RL*
Non-dimensional parameter (see Equations (9), (20a), (22a), (24a))
-
R*
Net radiation less ground heat flux (see Equations (15), (16))
-
T
Scaled temperature
-
T
1
Downstream scaled surface temperature
-
u
0
u
1(x)
Surface friction velocities for x <0, x0
-
U, W
Horizontal and vertical mean velocities
-
x, z
Horizontal and vertical co-ordinates
-
Z
i
Local roughness length
-
z
0, z
i
Roughness lengths for x < 0, x 0
-
Temperature
-
0,
1
Surface temperatures for x<0, x0
-
E
Non-dimensional absolute humidity gradient
-
H
Non-dimensional temperature gradient of heat flux
-
M
Non-dimensional wind shear
-
=
M
=
H
=
E
an assumption used in stable conditions
-
Air density
-
Absolute humidity
-
w
Density of water
-
Kinematic shear stress
-
Logarithmic height scale (= ln(z+z
1)/z
1) 相似文献
3.
A. M. Reynolds 《Boundary-Layer Meteorology》1998,88(1):77-86
Recently Wilson and Flesch (Boundary-Layer Meteorology, 84, 411-426, 1997) suggested that the average increment d z to the orientation = arctan(w/u) of the Lagrangian velocity-fluctuation vector can be used to distinguish the better Lagrangian stochastic models within the well-mixed class. Here it is demonstrated that the specification of d z constitutes neither a sufficient or universally applicable criterion to distinguish the better Lagrangian stochastic models within the well-mixed class. The hypothesis made by Wilson and Flesch that Lagrangian stochastic models with /PE irrotational are zero-spin models, having d z=0, is proven 相似文献
4.
Effects of heat and water vapor transport on eddy covariance measurement of CO2 fluxes 总被引:2,自引:0,他引:2
Flux densities of carbon dioxide were measured over an arid, vegetation-free surface by eddy covariance techniques and by a heat budget-profile method, in which CO2 concentration gradients were specified in terms of mixing ratios. This method showed negligible fluxes of CO2, consistent with the bareness of the experimental site, whereas the eddy covariance measurements indicated large downward fluxes of CO2. These apparently conflicting observations are in quantitative agreement with the results of a recent theory which predicts that whenever there are vertical fluxes of sensible or latent heat, a mean vertical velocity is developed. This velocity causes a mean vertical convective mass flux (=
cw for CO2, in standard notation). The eddy covariance technique neglects this mean convective flux and measures only the turbulent flux
c w. Thus, when the net flux of CO2 is zero, the eddy covariance method indicates an apparent flux which is equal and opposite to the mean convective flux, i.e.,
c w = –
c w. Corrections for the mean convective flux are particularly significant for CO2 because
cw and
c w are often of similar magnitude. The correct measurement of the net CO2 flux by eddy covariance techniques requires that the fluxes of sensible and latent heat be measured as well. 相似文献
5.
Sergej A. Kitaigorodskii Yury A. Volkov Andrey A. Grachev 《Boundary-Layer Meteorology》1995,76(1-2):181-197
The aerodynamic classification of the resistance laws above solid surfaces is based on the use of a so-called Reynolds roughness number Re
s =h
s
u
*/, whereh
s is the effective roughness height, -viscosity,u
*-friction velocity. The recent experimental studies reported by Toba and Ebuchi (1991), demonstrated that the observed variability of the sea roughness cannot be explained only on the basis of the classification of aerodynamic conditions of the sea surface proposed by Kitaigorodskii and Volkov (1965) and Kitaigorodskii (1968) even though the latter approach gains some support from recent experimental studies (see for example Geernaertet al. 1986). In this paper, an attempt is made to explain some of the recently observed features of the variability of surface roughness (Toba and Ebuchi, 1991; Donelanet al., 1993). The fluctuating regime of the sea surface roughness is also described. It is shown that the contribution from the dissipation subrange to the variability of the sea surface can be very important and by itself can explain Charnock's (1955) regime. 相似文献
6.
Turbulence mechanisms at an agricultural site 总被引:8,自引:0,他引:8
An extensive set of turbulence data from the 3- and 12-m heights taken over an agricultural site (Marsta, Sweden) are analyzed and compared with data from ideal sites.In unstable air, Monin-Obukhov similarity is found to be valid for the non-dimensional gradients of wind,
m
, temperature,
h
, and humidity,
e
, for (only a few data), for
T
/|T
*|,/
E
/|E
*| and for the non-dimensionalized inertial subrange spectra of temperature and humidity. Where comparison is possible, the unstable data also agree with those found in the Kansas study, with one remarkable exception, the inertial subrange constant of the temperature spectrum, 1, being only 0.39, compared to the value 0.80 found at the Kansas site.On the stable side, most similarity predictions break down, with most of the data differing systematically from the corresponding Kansas results, the only exception being . The inertial subrange constants for temperature, 1, and for humidity, 1 are found to have the same values, 0.39 and 0.30, respectively, as they do on the unstable side. Remarkable similarity is found for the shape of the stable u- and - and e-spectra. In addition, this shape is found to be identical with that found in Kansas. The peak wavelength of the stable u-, and -spectra is found to be about four times larger than it is for the corresponding Kansas spectra. This is interpreted to be a result of the increased macro-roughness at the Marsta site as compared with that at the Kansas site. A possible explanation for the low 1-value is discussed, suggesting that 1 is not a universal constant, but instead dependent on the turbulent structure. 相似文献
7.
Microwave vegetation optical depth and inverse modelling of soil emissivity using Nimbus/SMMR satellite observations 总被引:2,自引:0,他引:2
Summary A radiative transfer model has been used to determine the large scale effective 6.6 GHz and 37 GHz optical depths of the vegetation cover. Knowledge of the vegetation optical depth is important for satellite-based large scale soil moisture monitoring using microwave radiometry. The study is based on actual observed large scale surface soil moisture data and observed dual polarization 6.6 and 37 GHz Nimbus/SMMR brightness temperatures over a 3-year period. The derived optical depths have been compared with microwave polarization differences and polarization ratios in both frequencies and with Normalized Difference Vegetation Index (NDVI) values from NOAA/AVHRR. A synergistic approach to derive surface soil emissivity from satellite observed brightness temperatures by inverse modelling is described. This approach improves the relationship between satellite derived surface emissivity and large scale top soil moisture fromR
2=0.45 (no correction for vegetation) toR
2=0.72 (after correction for vegetation). This study also confirms the relationship between the microwave-based MPDI and NDVI earlier described and explained in the literature.List of Symbols
f
frequency [Hz]
-
f
i(p)
fractional absorption at polarizationp
-
h
surface roughness
-
h
h cos2
-
H
horizontal polarization
-
n
i
complex index of refraction
-
p
polarization (H orV)
-
R
s
microwave surface reflectivity
-
T
B(p)
brightness temperature at polarizationp
-
T
*
normalized brightness temperature
- T
polarization difference (T
v-T
H)
-
T
s
temperature of soil surface
-
T
c
temperature of canopy
-
T
max
daily maximum air temperature
-
T
min
daily minimum air temperature
-
V
vertical polarization
-
soil moisture distribution factor; also used for the constant to partition the influence of bound and free water components to the dielectric constant of the mixture
-
empirical complex constant related to soil texture
-
microwave transmissivity of vegetation (=e
–)
- *
effective transmissivity of vegetation (assuming =0)
-
microwave emissivity
-
s
emissivity of smooth soil surface
-
rs
emissivity of rough soil surface
-
vs
emissivity of vegetated surface
-
soil moisture content (% vol.)
-
K
dielectric constant [F·m–1]
-
K
fw
dielectric constant of free water [F·m–1]
-
K
ss
dielectric constant of soil solids [F·m–1]
-
K
m
dielectric constant of mixture [F·m–1]
-
K
o
permittivity of free space [8.854·10–12 F·m–1]
-
high frequency limit ofK
wf [F·m–1]
-
wavelength [m]
-
incidence angle [degrees from nadir]
-
polarization ratio (T
H/T
V)
- b
soil bulk density [gr·cm–3]
- s
soil particle density [gr·cm–3]
- R
surface reflectivity in red portion of spectrum
- NIR
surface reflectivity in near infrared portion of spectrum
- eff
effective conductivity of soil extract [mS·cm–1]
-
vegetation optical depth
- 6.6
vegetation optical depth at 6.6 GHz
- 37
vegetation optical depth at 37 GHz
- *
effective vegetation optical depth (assuming =0)
-
single scattering albedo of vegetation
With 12 Figures 相似文献
8.
A Field Study of the Mean Pressure About a Windbreak 总被引:3,自引:0,他引:3
John D. Wilson 《Boundary-Layer Meteorology》1997,85(3):327-358
To provide additional field data for assessingwindbreak flow models, mean ground-level pressurehas been measured upstream and downstream from along porous fence (height H = 1.25 m, resistancecoefficient k
r
= 2.4). Measurements were madeduring periods of near-neutral stability and near-normallyincident flow, with the fence standing on bare soil(roughness length, z
0
0.8 cm;H/z
0
160), or within a plant canopy. The mean pressure field,measured far from the ends of the fence, was foundto be quite insensitive to mean wind direction(
, zero for perpendicular flow), for|
| less than about 25°.In the absence of a canopy, during each measurementperiod the minimum pressure occurred at the closestsampling location to leeward of the windbreak, thepressure-gradient in most cases beingmaximally-adverse in the immediate lee, and decayingwith increasing downwind distance (x). On one day ofmeasurements, however, the pressure gradient over2 x/H 6 (H = windbreak height) resembled theleeward plateau identified by Wang and Taklein their numerical studies. Perhaps thisoccasional feature was only due to instrumenterror. Nevertheless a plateau of sorts wasindicated in similar measurements by Judd andPrendergast (with H = 1.92 m, z
0
1.2 cm;H/z
0
160, k
r
3). Therefore,existence of a leeward pressure plateau behind athin fence cannot be definitely ruled out.When the windbreak was placed in a canopy, minimumsurface pressure was displaced downwind. Thisagrees with the wind-tunnel study of Judd, Raupach and Finnigan,and is consistent with a simple simulation reported here. 相似文献
9.
Sylvain M. Joffre 《Boundary-Layer Meteorology》1982,24(2):211-229
Wind and temperature profiles from a 10-m mast were measured over the frozen Baltic Sea. The Monin-Obukhov similarity theory applies well to runs carefully selected according to stationarity criteria. This provides relatively low-scattered results with the roughness length z
0 0.04 cm, the drag coefficient C
D 1.5 × 10-3 and the Stanton number C
H 1.00 × 10-3 under near-neutral conditions. The roughness length, however, behaves in a peculiar way under intense stratification conditions. The reasons proposed for this could lead to an extension of the theory. The mechanisms for momentum and heat transfers are also examined, revealing that there are two different regimes, the smooth and the rough, for the wall friction but not for the heat transfer. Further, the scatter of the data for momentum and heat transfer under the aerodynamically rough regime can be explained by the distinction between the type of thermal stability conditions. 相似文献
10.
Mikhail Yu. Gershenzon Sergeid. Il'in Nikolai G. Fedotov Yulii M. Gershenzon Elena V. Aparina Vladislav V. Zelenov 《Journal of Atmospheric Chemistry》1999,34(1):119-135
A simple kinetic mechanism of nitrate radicals uptake on dry sea-salt NaCl, NaBr surfaces is proposed. The mechanism includes adsorption/desorption equilibrium and unimolecular decomposition of the adsorbed complex: NO3(g) + NaX(s) (NO3-NaX)(s); (NO3-NaX)(s) NaNO3 + X(s) Two techniques were used: the matrix isolation ESR and mass spectrometry. The uptake coefficient () is found to be dependent on exposure time of salt to NO3 for raw coating. The initial (t0) is higher than the observable steady-state obs. At room temperature obs is independent of [NO3] at low [NO3] = 3 × 109 - 1011 cm-3, but it is inversely proportional to [NO3] at concentrations higher than 1012 cm-3. At temperatures above 100 °C, obs becomes independent of [NO3] in a wider range of [NO3]. An increased number of dislocations is supposed to exist in the case of raw coating. Due to a wide spread of the surface sites binding energy with the ionic lattice near dislocations, the part of surface complexes has lower binding energy and "burns" more rapidly. That burning determines the transition from (t0) down to obs.The kinetic parameters and elementary rate coefficients are obtained. The recommended for low atmospheric NO3 concentration are in the range of 0.002 ± 0.04 for NaCl and 0.1-0.3 for NaBr depending on a mechanism of the (t) relaxation. 相似文献
11.
To determine if Cu mediated reactions on atmospheric particles are important to HO2 chemistry in the ambient atmosphere, Cu molalities were calculated from measured Cu aerosol particle concentrations, mass and number size distribution data from a site in central Sweden. A comparison of characteristic times indicates that at low relative humidities the reaction is limited by the mass transport of gas phase HO2 to the particle surface and not by the chemical kinetics of the aqueous reaction. Comparison of half-lives for particle reactions and the gas phase destruction of HO2 to form H2O2 indicate that heterogeneous reactions on aerosol particles may have important consequences on the chemistry of HO2 and H2O2 in the troposphere. 相似文献
12.
The Langevin equation is used to derive the Markov equation for the vertical velocity of a fluid particle moving in turbulent flow. It is shown that if the Eulerian velocity variance
wE is not constant with height, there is an associated vertical pressure gradient which appears as a force-like term in the Markov equation. The correct form of the Markov equation is: w(t + t) = aw(t) + b
wE + (1 – a)T
L
(
wE
2)/z, where w(t) is the vertical velocity at time t, a random number from a Gaussian distribution with zero mean and unit variance, T
L the Lagrangian integral time scale for vertical velocity, a = exp(–t/T
L), and b = (1 – a
2)1/2. This equation can be used for inhomogeneous turbulence in which the mean wind speed,
wE and T
L vary with height. A two-dimensional numerical simulation shows that when this equation is used, an initially uniform distribution of tracer remains uniform. 相似文献
13.
We propose a simple model for esimating the average number of occurrences per unit time (c
o) that a threshold concentration c
o is exceeded. It is based on the joint probability density of the observed concentration c(t) and its time derivative (t) under the assumption that c(t) is a stationary time series; this assumption leads to the hypothesis that c(t) and (t) are statistically independent. Adopting plausible forms of the frequency distributions of c and , we apply the model to diffusion from an infinite area source and from an elevated point source, both in the neutral boundary layer, and obtain simple results for (c
o) and the average duration of one excursion above c
o as functions of c
o, the mean and the standard deviation of the concentration, and surface-layer variables.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
14.
Dr. T. Murakami 《Meteorology and Atmospheric Physics》1990,44(1-4):85-100
Summary Interannual modes are described in terms of three-month running mean anomaly winds (u,v), outgoing longwave radiation (OLR), and sea surface temperature (T
*
). Normal atmospheric monsoon circulations are defined by long-term average winds (u
n,v
n) computed every month from January to December. Daily winds are grouped into three frequency bands, i.e., 30–60 day filtered winds (u
L,v
L); 7–20 day filtered winds (u
M,v
M); and 2–6 day filtered winds (u
S,v
S). Three-month running mean anomaly kinetic energy (signified asK
L
, K
M
, andK
S
, respectively) is then introduced as a measure of interannual variation of equatorial disturbance activity. Interestingly, all of theseK
L
, K
M
, andK
S
perturbations propagate slowly eastward with same phase speed (0.3 ms–1) as ENSO modes. Associated with this eastward propagation is a positive (negative) correlation between interannual disturbance activity (K
L
, K
M
, K
S
) and interannualu (OLR) modes. Namely, (K
L
, K
M
, K
S
) becomes more pronounced than usual nearly simultaneously with the arrival of westerlyu and negativeOLR (above normal convection) perturbutions. In these disturbed areas with (K
L
, K
M
, K
S
>0), upper ocean mixing tends to increase, resulting in decreased sea surface temperature, i.e.T
*
0. Thus, groups (not individual) of equatorial disturbances appear to play an important role in determiningT
*
variations on interannual time scales. HighestT
*
occurs about 3 months prior to the lowestOLR (convection) due primarily to radiational effects. This favors the eastward propagation of ENSO modes. The interannualT
*
variations are also controlled by the prevailing monsoonal zonal windsu
n, as well as the zonal advection of sea surface temperature on interannual time scales. Over the central Pacific, all of the above mentioned physical processes contribute to the intensification of eastward propagating ENSO modes. Over the Indian Ocean, on the other hand, some of the physical processes become insignificant, or even compensated for by other processes. This results in less pronounced ENSO modes over the Indian Ocean.With 10 FiguresContribution No. 89-6, Department of Meteorology, University of Hawaii, Honolulu, Hawaii. 相似文献
15.
A review of flux-profile relationships 总被引:33,自引:5,他引:33
A. J. Dyer 《Boundary-Layer Meteorology》1974,7(3):363-372
Flux-profile relationships in the constant flux layer are reviewed. The preferred relationships are found to be those of Dyer and Hicks (1970), namely,
H
=
W
=(1–16(z/L))–1/2,
M
=(1–16(z/L))–1/4 for the unstable region, and
H
=
W
=
M
= 1+5(z/L) for the stable region.The carefully determined results of Businger et al. (1971) remain a difficulty which calls for considerable clarification. 相似文献
16.
STAR (System for Transfer of Atmospheric Radiation) was developed to calculate accurately and efficiently the irradiance, the actinic flux, and the radiance in the troposphere. Additionally a very efficient calculation scheme to computer photolysis frequencies for 21 different gases was evolved. STAR includes representative data bases for atmospheric constituents, especially aerosol particles. With this model package a sensitivity study of the influence of different parameter on photolysis frequencies in particular of O3 to Singlet D oxygen atoms, of NO2, and of HCHO was performed. The results show the quantitative effects of the influence of the solar zenith angle, the ozone concentration and vertical profile, the aerosol particles, the surface albedo, the temperature, the pressure, the concentration of NO2, and different types of clouds on the photolysis frequencies.Notation
I
A(, )
actinic flux
-
I
H(, )
irradiance
-
L(, , , )
radiance
-
wavelength
-
azimuth angle
-
cosine of zenith angle
-
s
cosine of solar zenith angle
-
optical depth
-
s
scattering coefficient
-
c
extinction coefficient
-
o
single scattering albedo
-
p
mix
mixed phase function
-
g
mix
mixed asymmetry factor
-
J
gas
photolysis frequency 相似文献
17.
Bistability of the thermohaline circulation identified through comprehensive 2-parameter sweeps of an efficient climate model 总被引:2,自引:0,他引:2
R. Marsh A. Yool T. M. Lenton M. Y. Gulamali N. R. Edwards J. G. Shepherd M. Krznaric S. Newhouse S. J. Cox 《Climate Dynamics》2004,23(7-8):761-777
The effect of changes in zonal and meridional atmospheric moisture transports on Atlantic overturning is investigated. Zonal transports are considered in terms of net moisture export from the Atlantic sector. Meridional transports are related to the vigour of the global hydrological cycle. The equilibrium thermohaline circulation (THC) simulated with an efficient climate model is strongly dependent on two key parameters that control these transports: an anomaly in the specified Atlantic–Pacific moisture flux (Fa) and atmospheric moisture diffusivity (Kq). In a large ensemble of spinup experiments, the values of Fa and Kq are varied by small increments across wide ranges, to identify sharp transitions of equilibrium THC strength in a 2-parameter space (between Conveyor On and Off states). Final states from this ensemble of simulations are then used as the initial states for further such ensembles. Large differences in THC strength between ensembles, for identical combinations of Fa and Kq, reveal the co-existence of two stable THC states (Conveyor On and Off)—i.e. a bistable regime. In further sensitivity experiments, the model is forced with small, temporary freshwater perturbations to the mid-latitude North Atlantic, to establish the minimum perturbation necessary for irreversible THC collapse in this bistable regime. A threshold is identified in terms of the forcing duration required. The model THC, in a Conveyor On state, irreversibly collapses to a Conveyor Off state under additional freshwater forcing of just 0.1 Sv applied for around 100 years. The irreversible collapse is primarily due to a positive feedback associated with suppressed convection and reduced surface heat loss in the sinking region. Increased atmosphere-to-ocean freshwater flux, under a collapsed Conveyor, plays a secondary role. 相似文献
18.
Alistair D. Culf 《Boundary-Layer Meteorology》1994,70(1-2):37-49
Expressions for the equilibrium surface Bowen ratio (
s
) and equilibrium evaporation are derived for a growing convective boundary layer (CBL) in terms of the Bowen ratio at the top of the mixed layer
i
and the entrainment parameter A
R
. If AR is put equal to zero, the solution for
s
becomes-that previously obtained for the zero entrainment or closed box model. The Priestley-Taylor parameter is also calculated and plotted in terms ofA
R
and
i
. Realistic combinations of the atmospheric parameters give values of in the range 1.1 to 1.4. 相似文献
19.
Andrey A. Grachev 《Boundary-Layer Meteorology》1994,69(1-2):27-42
Frequency spectra of atmospheric turbulenceS
(f) in the inertial subrange are considered in the free convection regime over the sea surface in a case of motionless instrument measurements (Eulerian frequency spectra). The frequency spectra formulaef
*
S
(f)/
2
=c
(f
*/f)5/3 for wind velocity (=1–3), temperature (=t) and humidity (=e) fluctuations are derived on the basis of similarity theory and the –5/3 law. These relations also can be derived from a consideration of convective large-scale advection of small eddies. The frequency scalef
* = (N
1
2/)1/2 (H/z
2)1/3 is the lower bound of the inertial subrange and it is of order 10–2 Hz.The spectra formulae are compared with direct measurements of atmospheric turbulence from the fixed research tower in the coastal zone of the Black Sea in calm weather. It is shown that these formulae are realized at least over two to three decades of the frequency range (approximately from 10–2 to 10 Hz) and values of the numerical coefficients are found. The derived formulae can be used for calculations of sensible and latent heat fluxes by measuring the high-frequency range of spectra at a fixed point at low wind speeds when the conventional inertial dissipation method is not applicable. 相似文献
20.
Prof. S. Hastenrath 《Meteorology and Atmospheric Physics》1997,64(1-2):51-59
Summary During an expedition to the high Andes of Southern Peru in June–July 1977, measurements of direct solar radiation in four spectral bands (0.270–0.530–0.630–0.695–2.900 ) were conducted at six sites in elevations ranging from sea level to 5645 m. These measurements were evaluated in Langley plots to determine total optical depths () and irradiances at the top of the atmosphere. In addition, water vapor optical depths (wv) were calculated from the mean radiosounding over Lima during the expedition, and Rayleigh (ray) and ozone (oz) optical depths were obtained from published tabulations. Subtracting ray, oz, and wv from yielded estimates of aerosol optical depth aer. The components ray and oz decrease from the shorter towards the longer wavelength bands and from the lower towards the higher elevation sites; aer also decreases towards the higher elevations. Particularly pronounced is the decrease of aer and from the lowlands of the Pacific coast to the highlands of the interior, reflecting the effect of a persistent lower-tropospheric inversion and the contrast from the marine boundary layer to the clear atmosphere of the high Andes.With 4 Figures 相似文献