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1.
Turbulence statistics obtained by direct numerical simulations are analysed to investigate spatial heterogeneity within regular
arrays of building-like cubical obstacles. Two different array layouts are studied, staggered and square, both at a packing
density of . The flow statistics analysed are mean streamwise velocity (), shear stress (), turbulent kinetic energy (k) and dispersive stress fraction (). The spatial flow patterns and spatial distribution of these statistics in the two arrays are found to be very different.
Local regions of high spatial variability are identified. The overall spatial variances of the statistics are shown to be
generally very significant in comparison with their spatial averages within the arrays. Above the arrays the spatial variances
as well as dispersive stresses decay rapidly to zero. The heterogeneity is explored further by separately considering six
different flow regimes identified within the arrays, described here as: channelling region, constricted region, intersection
region, building wake region, canyon region and front-recirculation region. It is found that the flow in the first three regions
is relatively homogeneous, but that spatial variances in the latter three regions are large, especially in the building wake
and canyon regions. The implication is that, in general, the flow immediately behind (and, to a lesser extent, in front of)
a building is much more heterogeneous than elsewhere, even in the relatively dense arrays considered here. Most of the dispersive
stress is concentrated in these regions. Considering the experimental difficulties of obtaining enough point measurements
to form a representative spatial average, the error incurred by degrading the sampling resolution is investigated. It is found
that a good estimate for both area and line averages can be obtained using a relatively small number of strategically located
sampling points. 相似文献
2.
In this study, profile functions for flux calculations during unstable conditions are proposed and examined. These functions are based on a direct interpolation for the dimensionless wind speed and temperature gradients between the standard Businger–Dyer formulae,
,
, and free convection forms,
,
being the Monin–Obukhov stability parameter. A previously presented interpolation between the corresponding profile relationships, in attempting to provide a general relationship for the whole unstable regime, leads to serious restrictions for the values of
in the free convection forms. These restrictions rendered available experimental data almost inapplicable, since the behaviour of the formulae in the near-neutral range controls the values of those parameters. The proposed interpolation provides functions that, firstly, fit the standard Businger–Dyer forms for near-neutral conditions and, secondly, satisfy the asymptotic behaviour as
, permitting wider ranges of possible
values. This step is very important, taking into account the large spread of the experimental data. Thus, as further and more accurate observations at strong instability become available, this approach could prove very efficient in fitting these data while retaining correct near-neutral behaviour. 相似文献
3.
The present study investigated the chemical composition of wet atmospheric precipitation in India’s richest coal mining belt.
Total 418 samples were collected on event basis at six sites from July to October in 2003 and May to October in 2004 and analysed
for pH, EC, F−, Cl−, , , Ca2+, Mg2+, Na+, K+ and . The average pH value (5.7) of the rainwater of the investigated area is alkaline in nature. However, the temporal pH variation
showed the alkaline nature during the early phase of monsoonal rainfall but it trends towards acidic during the late and high
rainfall periods. The rainwater chemistry of the region showed high contribution of Ca2+ (47%) and (21%) in cations and (55%) and Cl− (23%) in anionic abundance. The high non seas salt fraction (nss) of Ca2+ (99%) and Mg2+ (96%) suggests crustal source of the ions, while the high nss (96%) and high ratio signifying the impact of anthropogenic sources and the source of the acidity. The ratio of varies from 0.03 to 3.23 with the average value of 0.84 suggesting that Ca2+ and play a major role in neutralization processes. The assessment of the wet ionic deposition rates shows no any specific trend,
however Ca2+ deposition rate was highest followed by and
. 相似文献
4.
Time Scales in the Unstable Atmospheric Surface Layer 总被引:2,自引:2,他引:0
Calculation of eddy covariances in the atmospheric surface layer (ASL) requires separating the instantaneous signal into mean
and fluctuating components. Since the ASL is not statistically stationary, an inherent ambiguity exists in defining the mean
quantities. The present study compares four methods of calculating physically relevant time scales in the unstable ASL that
may be used to remove the unsteady mean components of instantaneous time signals, in order to yield local turbulent fluxes
that appear to be statistically stationary. The four mean-removal time scales are: (t
c
) based on the location of the maximum in the ogive of the heat flux cospectra, () the location of the zero crossing in the multiresolution decomposition of the heat flux, (t
*) the ratio of the mixed-layer depth over the convective velocity, and () the convergence time of the vertical velocity and temperature variances. The four time scales are evaluated using high quality,
three-dimensional sonic anemometry data acquired at the Surface Layer Turbulence and Environmental Science Test (SLTEST) facility
located on the salt flats of Utah’s western desert. Results indicate that and , with t
c
achieving values about 2–3 times greater than t
*. The sensitivity of the eddy covariances to the mean-removal time scale (given a fixed 4-h averaging period during midday)
is also demonstrated. 相似文献
5.
A comprehensive model for the prediction of concentration fluctuations in plumes dispersing in the complex and highly disturbed
wind flows in an urban environment is formulated. The mean flow and turbulence fields in the urban area are obtained using
a Reynolds-averaged Navier-Stokes (RANS) flow model, while the standard k-ϵ turbulence model (k is the turbulence kinetic energy and ϵ is the viscous dissipation rate) is used to close the model. The RANS model provides a specification of the velocity statistics
of the highly disturbed wind flow in the urban area, required for the solution of the transport equations for the mean concentration
and concentration variance (both of which are formulated in the Eulerian framework). A physically-based formulation for the scalar dissipation time
scale t
d
, required for the closure of the transport equation for , is presented. This formulation relates t
d
to an inner time scale corresponding to “internal” concentration fluctuation associated with relative dispersion, rather
than an outer time scale associated with the entire portion of the fluctuation spectrum. The two lowest-order moments of concentration
( and ) are used to determine the parameters of a pre-chosen functional form for the concentration probability density function
(clipped-gamma distribution). Results of detailed comparisons between a water-channel experiment of flow and dispersion in
an idealized obstacle array and the model predictions for mean flow, turbulence kinetic energy, mean concentration, concentration
variance, and concentration probability density function are presented. 相似文献
6.
We describe one-dimensional (1D) simulations of the countergradient zone of mean potential temperature observed in the convective boundary layer (CBL). The method takes into account the third-order moments (TOMs) in a turbulent scheme of relatively low order, using the turbulent kinetic energy equation but without prognostic equations for other second-order moments. The countergradient term is formally linked to the third-order moments and , and a simple parameterization of these TOMs is proposed. It is validated for several cases of a dry CBL, using large-eddy simulations that have been realized from the MESO-NH model. The analysis of the simulations shows that TOMs are responsible for the inversion of the sign of in the higher part of the CBL, and budget analysis shows that the main terms responsible for turbulent fluxes and variances are now well reproduced. 相似文献
7.
In order to quantitatively investigate the role of leads and sea-ice in air-mass modification, aircraft observations were
conducted over the partially ice-covered Sea of Okhotsk. We investigated two cold-air outbreak events with different sea-ice
concentrations. In both cases, the difference between the temperatures of surface air and the sea surface (ΔT) dropped rapidly with the accumulated fetch-width of leads up to about 35-40 km, and then decreased very slowly. The surface
sensible heat flux originating from open water was about 300 W m−2 within a few kilometres from the coast and decreased with increasing accumulated fetch-width. The sensible heat flux was
about 100 W m−2 on average. These results indicate that the downwind air-mass modification depends mainly on the total (accumulated) extent
of open water. The total buoyancy flux
calculated by the joint frequency distribution method correlated very well with ice concentration. Such a relationship was
not clear in the case of the moisture flux
. The ratio between rising thermals
and cold downdrafts
differed significantly between upwind and downwind regions; that is, the buoyancy flux was dominated by
in the developing stage of the boundary layer, while
also became important after the development of the boundary layer. 相似文献
8.
Energy- and flux-budget (EFB) turbulence closure model for stably stratified flows. Part I: steady-state,homogeneous regimes 总被引:3,自引:3,他引:0
S. S. Zilitinkevich T. Elperin N. Kleeorin I. Rogachevskii 《Boundary-Layer Meteorology》2007,125(2):167-191
We propose a new turbulence closure model based on the budget equations for the key second moments: turbulent kinetic and
potential energies: TKE and TPE (comprising the turbulent total energy: TTE = TKE + TPE) and vertical turbulent fluxes of
momentum and buoyancy (proportional to potential temperature). Besides the concept of TTE, we take into account the non-gradient
correction to the traditional buoyancy flux formulation. The proposed model permits the existence of turbulence at any gradient
Richardson number, Ri. Instead of the critical value of Richardson number separating—as is usually assumed—the turbulent and
the laminar regimes, the suggested model reveals a transitional interval, , which separates two regimes of essentially different nature but both turbulent: strong turbulence at ; and weak turbulence, capable of transporting momentum but much less efficient in transporting heat, at . Predictions from this model are consistent with available data from atmospheric and laboratory experiments, direct numerical
simulation and large-eddy simulation. 相似文献
9.
A dataset from two campaigns conducted at the Vielsalm experimental site in Belgium was used as a basis for discussing some
methodological problems and providing intermediate results on estimating CO2 advection. The analysis focused on the horizontal [CO2] gradient and on the vertical velocity w, the variables most affected by uncertainty. The sampling error for half-hourly horizontal [CO2] gradients was estimated to be 1.3 μmol mol−1. Despite this important random error for half-hour estimations of [CO2], the mean horizontal [CO2] gradients in advective conditions were shown to be representative at the ecosystem scale and to extend only to the lowest
part of a drainage sub-layer, which developed in the trunk space. By contrast, under daytime conditions, this gradient was
shown to be more sensitive to local source heterogeneities. The estimation of the short-term averaged vertical velocity (
was the greater source of error when computing advection terms. The traditional correction methods used to obtain
are discussed and a (co)sine correction is tested to highlight the instrumental origin of the offset in w. A comparison of measurements by sonic anemometers placed close together above the canopy showed that the uncertainty on
was 0.042 m s−1, which is of the same order of magnitude as the velocity itself. In addition, as the drainage sub-layer is limited to the
lowest part of the canopy, the representativeness of
is questionable. An alternative computation using the divergence of the horizontal wind speed in the trunk space produced
a
estimation that was four times lower than the single-point measurement. However, this value gives a more realistic estimate
of the vertical advection term and improves the CO2 budget closure at the site. 相似文献
10.
Panagiotis T. Nastos Dimitrios Alexakis Helen A. Kanellopoulou Akindinos E. Kelepertsis 《Journal of Atmospheric Chemistry》2007,58(2):167-179
The goal of this study is to determine the chemical composition of rain, in the wider region of Athens, Greece for the time
period 1st September 2001 to 31st August 2002. Two model automatic rain samplers were installed in the Meteorological Station
of Laboratory of Climatology (latitude: 37° 58′ N, longitude: 23° 47′ E) inside the Athens University Campus and in a site
at Heraklio Attica, a northern suburb of Athens (latitude: 38° 03′ N, longitude: 23° 45′ E). The concentrations (μeq l−1) of the major cations (H+, Na+, K+, Ca2+ and Mg2+) and anions (Cl−, , και ), as well as pH and conductivity of rain in 39 total samples were determined. The figures of pH range from 6.4 to 8.4 and
conductivity from 8 to 207 μS cm−1. The analysis showed that Ca2+ ions are abundant within all examined samples, while and present the highest concentrations from the anions. In order to find out the origin of the air masses, the air mass back
trajectories were calculated. Five sectors of the origin of air masses were revealed: the North, the South, the Local, the
West and the East sector. Multivariate methods included Factor Analysis and Discriminant Analysis were applied to the examined
ion concentrations and three main factors were extracted, which discriminated the ions according to their origin. The first
group of ions is interpreted as the result of the anthropogenic activity, the second group represents the acidity–alkalinity
independently of their source and the third one the marine influence. 相似文献
11.
The turbulent flow inside dense canopies is characterized by wake production and short-circuiting of the energy cascade. How these processes affect passive scalar concentration variability in general and their spectral properties in particular remains a vexing problem. Progress on this problem is frustrated by the shortage of high resolution spatial concentration measurements, and by the lack of simplified analytical models that connect spectral modulations in the turbulent kinetic energy (TKE) cascade to scalar spectra. Here, we report the first planar two-dimensional scalar concentration spectra (ϕ
cc
) inside tall canopies derived from flow visualization experiments. These experiments were conducted within the deeper layers of a model canopy composed of densely arrayed cylinders welded to the bottom of a large recirculating water channel. We found that in the spectral region experiencing wake production, the ϕ
cc
exhibits directional scaling power laws. In the longitudinal direction (x), or the direction experiencing the largest drag force, the ϕ
cc
(k
x
) was steeper than and followed an approximate at wavenumbers larger than the injection scale of wake energy, where k
x
is the longitudinal wavenumber. In the lateral direction (y), the spectra scaled as up to the injection scale, and then decayed at an approximate
power law. This departure from the classical inertial subrange scaling (i.e., k
−5/3) was reproduced using a newly proposed analytical solution to a simplified scalar spectral budget equation. Near the velocity viscous dissipation range, the scalar spectra appear to approach an approximate k
−3, a tantalizing result consistent with dimensional analysis used in the inertial-diffusive range. Implications to subgrid modelling for large-eddy simulations (LES) inside canopies are briefly discussed. 相似文献
12.
Role of atmospheric ammonia in the formation of inorganic secondary particulate matter: A study at Kanpur,India 总被引:1,自引:0,他引:1
Mukesh Sharma Shyam Kishore S. N. Tripathi S. N. Behera 《Journal of Atmospheric Chemistry》2007,57(1):1-17
Levels of fine Particulate Matter (PMfine), SO2 and NOx are interlinked through atmospheric reactions to a large extent. NOx, NH3, SO2, temperature and humidity are the important atmospheric constituents/conditions governing formation of fine particulate sulfates
and nitrates. To understand the formation of inorganic secondary particles (nitrates and sulfates) in the atmosphere, a study
was undertaken in Kanpur, India. Specifically, the study was designed to measure the atmospheric levels of covering winter and summer seasons and day and night samplings to capture the diurnal variations. Results showed are found to be significantly high in winter season compared to the summer season. In winter, the molar ratio of to was found to be greater than 2:1. This higher molar ratio suggests that in addition to (NH4)2SO4, NH4NO3 will be formed because of excess quantity of present. In summer, the molar ratio was less than 2:1 indicating deficit of to produce NH4NO3. The nitrogen conversion ratio (NO2 to NO3) was found to be nearly 50% in the study area that suggested quick conversion of NO2 into nitric acid. As an overall conclusion, this study finds that NH3 plays a vital role in the formation of fine inorganic secondary particles particularly so in winter months and there is a
need to identify and assess sources of ammonia emissions in India. 相似文献
13.
We present surface-layer measurements of temperature fluctuation variance from a site characterized by small-scale inhomogeneities.
Periods of marked radiative forcing are selected. The data characterized by diabatic conditions and vertical heat flux larger
than some threshold (here, chosen to be 0.01 K ms−1) agree quite well with the convective scaling in unstable cases, and with the z-less parameterisation (with a large scatter) in stable cases. For near-neutral cases, the similarity function diverges because of the loss of significance
of the temperature scale. Departures from similarity are highlighted in cases with smaller thermal fluxes, because horizontal
heterogeneity and unsteadiness become important as production terms. 相似文献
14.
Effects of water vapour on the structure parameter of the refractive index for near-infrared radiation 总被引:2,自引:2,他引:0
A. F. Moene 《Boundary-Layer Meteorology》2003,107(3):635-653
The refractive index of air (n) mainly depends on temperature andwater vapour content. For near-infrared radiation, temperature isthe main determining factor. To determinethe structure parameter of temperature (
) fromthe structure parameter of the refractive index(
), the influence ofwater vapour content on n needs to be taken into account as acorrection. Three levels of approximation are presented. The firstinvolves the standard deviations of T and q (T andq) as well as the correlation coefficient betweenT and q (RTq). The second approximation involvesRTq and the Bowen ratio (), and the last uses only the Bowen ratio.The latter is the classical Bowen ratio correction.Evaluation of the validity of the assumptions used in the derivationreveals that a large error may be introduced (for situations withRTq < 0.8) by replacing T/qwith the Bowen ratio.Consequently, estimating
from
using the Bowen ratiocan contain errors of 5–40% for || < 1. Adding RTqas extra information reduces the errors only marginally. For || > 1,the correction is small, and all three approximations give errors of lessthan 1% in
. When
is used to compute the sensible heat flux,the influence of the quality of the correction forwater vapour fluctuations on the measured energy balance is small: forsmall ||, the correction is large, but the absolute value ofthe heat flux is small, whereas for large ||, the correctionis insignificant. 相似文献
15.
J. E. Pinzón C. E. Puente M. B. Parlange W. Eichinger 《Boundary-Layer Meteorology》1995,76(4):323-347
Accurate and fast-response measurements of space-time observations of specific humidity were made above a drying land surface at the University of California at Davis, using the Los Alamos water Raman-lidar. In an attempt to quantify the space-time intermittency features of turbulent flows in the lower atmosphere, a multifractal analysis of these water vapour measurements was performed. The structure of the specific humidity, (x, t), was analyzed quantifying a scalar gradient measure
both in time and space, for all possible one-dimensional cuts, i.e.
and
. The results confirm the multifractal nature of this scalar gradient measure (a type of scalar dissipation rate) and show that humidity measurements at fixed times (x) are more intermittent (e.g. have less entropy dimension) than those at fixed locations in space (t). Similar multifractal behaviour of the spatial data, with and without a transformation from the observed wind velocities, supports the validity of Taylor's hypothesis for the studied fields. 相似文献
16.
A modification of the most popular two-equation (E–φ) models, taking into account the plant drag, is proposed. Here E is the turbulent kinetic energy (TKE) and φ is any of the following variables: El (product of E and the mixing length l),
(dissipation rate of TKE), and ω (specific dissipation of TKE,
). The proposed modification is due to the fact that the model constants estimated experimentally for ‘free-air’ flow do not allow for adequate reconstruction of the ratio between the production and dissipation rates of TKE in the vegetation canopy and have to be adjusted. The modification is universal, i.e. of the same type for all E–φ models considered. The numerical experiments carried out for both homogeneous and heterogeneous plant canopies with E–φ models (and with the E–l model taken as a kind of reference) show that the modification performs well. They also suggest that E– and E–ω schemes are more promising than the E–El scheme for canopy flow simulation since they are not limited by the need to use a wall function.In addition, a new parameterization for enhanced dissipation within the plant canopy is derived. It minimizes the model sensitivity to C
μ, the key parameter for two-equation schemes, and whose estimates unfortunately vary considerably from experiment to experiment. The comparison of results of new modified E– and E –ω models with observations from both field and wind-tunnel experiments shows that the proposed parameterization is quite robust. However, because of uncertainties with the turbulence Prandtl and Schmidt numbers for the E– model within the canopy, the E–ω model is recommended for future implementation, with the suggested modifications. 相似文献
17.
Reactions of levoglucosan with produced from Fenton chemistry were studied in solution serving as a proxy for biomass burning aerosols. Two modes of oligomerization
(≤2000 u) were observed for reaction times between 1 and 7 days using matrix-assisted laser desorption time-of-flight mass
spectrometry (MALDI-TOF-MS) and laser desorption ionization time-of-flight mass spectrometry (LDI-TOF-MS). Single-mass unit
continuum mass distributions with dominant −2 u patterns were measured and superimposed by a +176/+162 u oligomer series.
This latter oligomer pattern was attributed to a Criegee rearrangement (+14 u) of levoglucosan, initiated by , forming a lactone (176 u). The acid-catalyzed reaction of any ROH from levoglucosan (+162 u) forms an ester through transesterification
of the lactone functionality, whereupon propagation forms polyesters. Proposed products and chemical mechanisms are suggested
as sources and precursors of humic-like substances (HULIS), which are known to possess a large saccharic component and are
possibly formed from biomass burning aerosols (Andreae, Global Biomass Burning, MIT Press, Cambridge, Massachusetts, 3–21,
1991). 相似文献
18.
The two-year (1999–2000) rainwater chemistry at two monitoring sites in nearby coastal areas [Taiwan (TW) and Hong Kong (HK)]
within the Western Pacific region has been studied. The volume weighted average pH values for the entire sampling period in
TW and HK were 4.6 and 4.2, respectively. Sea salt Na+ and Cl− were the most abundant species in the TW samples but and H+ were the most abundant in the HK samples. The sea salt and concentrations at TW were higher than those at HK both in the cold and warm seasons. Chloride depletion was minimal in the
rainwater samples at both sites. Non seasalt- was associated with . Under the influence of the East Asian Winter Monsoon, the back-trajectory studies revealed that elevated anthropogenic species
concentrations were associated with trajectories (1) very near to the continental boundary layer of Mainland China; or (2)
along the coastline of Eastern China where large cities/industrial areas are located or (3) passing through the region of
stagnant air over Northern/Eastern China. The lowest anthropogenic and crustal species concentrations measured in HK are associated
with the summer monsoon and are attributed not only to the clean marine air masses but also to the relatively low SO2, NO
x
and NH3 emissions from the South/ South East Asian countries, as well as infrequent biomass burning activities and wet scavenging
at sources during the summer months. Approaching tropical cyclones led to the lowest pH values (4.2 in TW and 3.8 in HK) amongst
the other weather categories. The findings here have been compared with other studies within East Asia and elsewhere. 相似文献
19.
Turbulent Intensities and Velocity Spectra for Bare and Forested Gentle Hills: Flume Experiments 总被引:1,自引:1,他引:0
To investigate how velocity variances and spectra are modified by the simultaneous action of topography and canopy, two flume
experiments were carried out on a train of gentle cosine hills differing in surface cover. The first experiment was conducted
above a bare surface while the second experiment was conducted within and above a densely arrayed rod canopy. The velocity
variances and spectra from these two experiments were compared in the middle, inner, and near-surface layers. In the middle
layer, and for the canopy surface, longitudinal and vertical velocity variances () were in phase with the hill-induced spatial mean velocity perturbation (Δu) around the so-called background state (taken here as the longitudinal mean at a given height) as predicted by rapid distortion
theory (RDT). However, for the bare surface case, and remained out of phase with Δu by about L/2, where L is the hill half-length. In the canopy layer, wake production was a significant source of turbulent energy for , and its action was to re-align velocity variances with Δu in those layers, a mechanism completely absent for the bare surface case. Such a lower ‘boundary condition’ resulted in longitudinal
variations of to be nearly in phase with Δu above the canopy surface. In the inner and middle layers, the spectral distortions by the hill remained significant for the
background state of the bare surface case but not for the canopy surface case. In particular, in the inner and middle layers
of the bare surface case, the effective exponents derived from the locally measured power spectra diverged from their expected
− 5/3 value for inertial subrange scales. These departures spatially correlated with the hill surface. However, for the canopy
surface case, the spectral exponents were near − 5/3 above the canopy though the minor differences from − 5/3 were also
correlated with the hill surface. Inside the canopy, wake production and energy short-circuiting resulted in significant departures
from − 5/3. These departures from − 5/3 also appeared correlated with the hill surface through the wake production contribution
and its alignment with Δu. Moreover, scales commensurate with Von Karman street vorticies well described wake production scales inside the canopy,
confirming the important role of the mean flow in producing wakes. The spectra inside the canopy on the lee side of the hill,
where a negative mean flow delineated a recirculation zone, suggested that the wake production scales there were ‘broader’
when compared to their counterpart outside the recirculation zone. Inside the recirculation zone, there was significantly
more energy at higher frequencies when compared to regions outside the recirculation zone. 相似文献
20.
N. Carrasco J. F. Doussin M. O’Connor J. C. Wenger B. Picquet-Varrault R. Durand-Jolibois P. Carlier 《Journal of Atmospheric Chemistry》2007,56(1):33-55
This article presents a complete study of the diurnal chemical reactivity of the biogenic volatile organic compound (BVOC), 2-methyl-3-buten-2-ol (MBO) in the troposphere. Reactions of MBO with OH and with ozone were studied to analyse the respective parts of both processes in the global budget of MBO atmospheric reactivity. They were investigated under controlled conditions for pressure (atmospheric pressure) and temperature (298 ± 2 K) using three complementary European simulation chambers. Reaction with OH radicals was studied in the presence of and in the absence of NO
x
. The kinetic study was carried out by relative rate study using isoprene as a reference. The rate constant found for this reaction was molecule−1 cm3 s−1. FTIR spectroscopy, DNPH- and PFBHA-derivatisation analyses were performed for reactions with both OH radicals and ozone. In both reactions, the hydroxycarbonyl compound, 2-hydroxy-2-methylpropanal (HMPr) was positively identified and quantified, with a yield of in the reaction with OH, and a yield of and 0.84 ± 0.08 in the reaction with ozone under dry (HR < 1%) and humid conditions (HR = 20%–30%). A primary production of two other carbonyl compounds, acetone , and formaldehyde was found in the case of the dry ozonolysis experiments. Under humid conditions, only formaldehyde was co-produced with HMPr as a primary carbonyl compound, with a yield of . For the reaction with OH, three other carbonyl compounds were detected, acetone , formaldehyde and glycolaldehyde . In addition some realistic photo-oxidation experiments were performed to understand in an overall way the transformations of MBO in the atmosphere. The realistic photo-oxidation experiments were conducted in the EUPHORE outdoor simulation chamber. It was found that this compound is a weak secondary aerosol producer (less than 1% of the carbon balance). But it was confirmed that it is a potentially significant source of acetone, Δ[Acetone]/Δ[MBO] = 0.45. With our experimental conditions ([MBO]0 = 200 ppb, [NO]o = 50 ppb), an ozone yield of Δ[O3]/Δ[MBO] = 1.05 was found. 相似文献