KEYWORDS: Clouds, Meteorology, Aerosols, Environmental sensing, Information science, Information technology, Radiation effects, Diffusion, Solar energy, Computing systems
A new commercial instrument for measuring Cloud Condensation Nuclei (CCN), the Droplet Measurement
Technologies Cylindrical Continuous-Flow Streamwise Thermal Gradient CCN Chamber (CFSTGC), installed on
Mount Huang meteorological station (30°19'N, 118°14'E, 1840m above sea level) from 16 April to 28 July 2008. This
instrument can measure CCN concentrations at supersaturations from 0.1% to 2% (potentially up to 6%), as well as a 1
Hz sampling rate that is sufficient for ground-based or airborne platform operation. The instrument records data
continuously at 1-second intervals 24 hours a day. For the 98-day, continuous study the average CCN concentration was
found to range between a few hundred and a few thousand nuclei per cm3 at supersaturations between 0.3 and 1%.
Diurnal variations were observed, as well as other possible influences, such as wind speed, wind direction and mixing
depth. At a constant supersaturation of 0.5% the CCN concentration is typically on the order of 361 to 2297 nuclei per
cm3. A description of the instrumentation and early observations are presented and discussed.
Airborne measurements of the concentration and size distribution of aerosol particles over Hebei area, northern China,
are analyzed. The preliminary results show that, depending on the meteorological situations, the maximum mean number
concentration of aerosol particles ranges from 5000 to 105 cm-3 near the ground and decreases exponentially to 1500-
3500 cm-3 above the boundary layer. It is also found that particle size distributions are the broadest close to the surface
and become narrower with increasing height. The particle size distributions can be fitted with three or four lognormal
distribution functions. Besides the emission rate and the distance from the source region, the results indicate that aerosol
particle size is to a large extent dependent on the ambient atmospheric conditions such as humidity, and the presence of
temperature inversion layers and cloud layers. Higher humidity and the presence of cloud layers may enhance particle
growth and lead to larger particle size due to condensation and gas to particle conversion.m
The Model of Atmospheric Transport and Chemistry (MATCH) developed by the National Center for Atmospheric
Research (NCAR) is used to calculate the aerosol optical depth (AOD) over China in 2006, with the updated emission
inventory of Streets (2007) and NCEP/NCAR reanalysis data as its inputs. The simulation results of AOD are then
compared with observational data from Chinese Sun Hazemeter Network (CSHNET), Aerosol Robotics Network
(AERONET) at more than 23 stations over China, and Moderate Resolution Imaging Spectroradiometer (MODIS)
satellite data. The model reproduces most of the prominent features in the CSHNET observation data with an overall
agreement within a factor of 2. However, there exist large differences between the simulation and the MODIS data, due
to the large uncertainties in the model and the satellite data.
The effect of cirrus cloud on radiative transfer depends on its microphysical properties. The water content and number
concentrations of ice particles in tropical anvil cirrus measured during the ACTIVE (Aerosol and Chemical Transport in
Tropical Convection) field campaign (from November 2005 to February 2006 in Darwin area, Australia) are analyzed.
Some advanced particle probes are utilized during this campaign, including Cloud Imaging Probe (CIP) and Cloud
Particle Imager (CPI).
A statistical analysis of the fifteen cases (only the slow phase of anvil cirrus with the height ranging from 9.7 to 14.9 km
and temperature ranging from -70.4°C to -30.0°C, are considered) shows that the typical value of ice water content
(IWC) is 10-2 g m-3, and the number concentrations of ice particles measured by CIP (>100μm) and CPI (>5μm), are 101
and 102 L-1, respectively. The changes in median of IWC in anvil cirri with temperature (or altitude) are examined and
compared among different phases of Australian monsoon.
The absorption and scattering coefficients of atmospheric aerosols were continuously measured with a Photoacoustic
Soot Spectrometer (PASS, DMT Inc. USA) at a suburb site of Nanjing, one of the regions experiencing rapid
industrialization in China. The measurements were carried out during autumn and winter 2007. A preliminary analysis of
the data shows that, the scattering coefficient, Bscat, is two to ten times larger than the absorption coefficient, Babs,
implying that the aerosols formed/emitted in this area are more scattering than previous assumed, and can be more
important in cooling the Earth-atmosphere system. The results also indicate that the absolute values of both parameters
are very much dependent on the meteorological conditions, such as wind speed and direction, fog, rain, etc. as well as the
time of the day. Higher values often appear at nighttimes when wind is weak, especially when a temperature inverse
layer is present near the surface. Higher values of Bscat and Babs were also observed under hazy and foggy weather
conditions or when wind is blown from east, where a large industrial zone is located. Simultaneous measurements of the
number concentrations, chemical compositions, and size distributions of aerosol particles are used to explain the
characteristics of the changes in Bscat and Babs.
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