A monitoring programme for halogenated climate-altering gases has been established in the frame of the SHARE EV-K2 -CNR project at the Nepal Climate Laboratory – Pyramid in the Himalayan range at the altitude of 5079 m a.s.l. The site is very well located to provide important insights on changes in atmospheric composition in a region that is of great significance for emissions of both anthropogenic and biogenic halogenated compounds. Measurements are performed since March 2006, with grab samples collected on a weekly basis. The first three years of data have been analysed. After the identification of the atmospheric background values for fourteen halocarbons, the frequency of occurrence of pollution events have been compared with the same kind of analysis for data collected at other global background stations. The analysis showed the fully halogenated species, whose production and consumption are regulated under the Montreal Protocol, show a significant occurrence of “above the baseline” values, as a consequence of their current use in the developing countries surrounding the region, meanwhile the hydrogenated gases, more recently introduced into the market, show less frequent spikes. Atmospheric concentration trends have been calculated as well, and they showed a fast increase, ranging from 5.7 to 12.6%, of all the hydrogenated species, and a clear decrease of methyl chloroform(-17.7%).The comparison with time series from other stations has also allowed to derive Meridional gradients, which are absent for long living well mixed species, while for the more reactive species, the gradient in creases inversely with respect to their atmospheric lifetime. The effect of long range transport and of local events on the atmospheric composition at the station has been analysed as well, allowing the identification of relevant source regions the Northern half of the Indian sub-continent. Also, at finer spatial scales, a smaller, local contribution of forest fires from the Khumbu valley has been detected.

A Cimel sunphotometer operating in the framework of the AERONET project has been installed at the Himalayan Ev-K2-CNR Pyramid (5079 m a.s.l.) in the year 2006, as site Ev-K2-CNR. The observational activity will provide a characterization of the optical and microphysical properties of atmospheric aerosols, in particular of the atmospheric brown cloud (ABC) in the Himalayan region. This paper will describe the Cimel sunphotometer measurement technique, will introduce to the AERONET programme and will evaluate the contribution of the proposed Ev-K2-CNR AERONET site to the study of the ABC.

The Vaisala Weather Transmitter WXT520 measures 6 most essential weather parameters as WXT510 Specifications: Low power consumption - works also with solar panels Compact, light-weight Easy to install No moving parts Vaisala Configuration Tool for PC USB connection Housing with mounting kit IP66 Applications: weather stations, dense networks, harbors, marinas

In the framework of the SusKat (Sustainable Atmosphere for the Kathmandu Valley), ABC-UNEP and NextData Projects, CNR-ISAC and URT Ev-K2-CNR participated in the setting-up of the Kathmandu (Pakanajol) monitoring station. In particular, the station is equipped with: • meteorological sensors; • global pyranometer for downward solar short-wave radiation; • surface ozone analyzer; • optical particle counter for aerosol size distribution from 0.3 to 10 micron; • on-line PM1/PM10 analyser ; • multi-angle absorption photometer for equivalent black carbon mass measurement.

In this work we present the new ABC-Pyramid Atmospheric Research Observatory (Nepal, 27.95 N, 86.82 E) located in the Himalayas, specifically in the Khumbu valley at 5079 m a.s.l. This measurement station has been set-up with the aim of investigating natural and human-induced environmental changes at different scales (local, regional and global). After an accurate instrumental set-up at ISAC-CNR in Bologna (Italy) in autumn 2005, the ABC-Pyramid Observatory for aerosol (physical, chemical and optical properties) and trace gas measurements (ozone and climate altering halocarbons) was installed in the high Khumbu valley in February 2006. Since March 2006, continuous measurements of aerosol particles (optical and physical properties), ozone (O3) and meteorological parameters as well as weekly samplings of particulate matter (for chemical analyses) and grab air samples for the determination of 27 halocarbons, have been carried out. These measurements provide data on the typical atmospheric composition of the Himalayan area between India and China and make investigations of the principal differences and similarities between the monsoon and pre-monsoon seasons possible. The study is carried out within the framework of the Ev-K2-CNR “SHARE-Asia” (Stations at High Altitude for Research on the Environment in Asia) and UNEP—“ABC” (Atmospheric Brown Clouds) projects. With the name of “Nepal Climate Observatory—Pyramid” the station is now part of the Observatory program of the ABC project.

The OPC, manifactured by FAI, permit a - Characterization of the temporal trends of the particulate matter granulometric distribution as a support and integration to information about air quality - Real-time estimation of the PM1, PM2.5, PM10, TPS mass concentration of the airborne particulate matter. Main features - Measurement principle: laser scattering on elliptical mirror - Optical channels: 8 optical channels with thresholds having lower limits [µm]: 0.28, 0.4, 0.5, 0.7, 1.1, 2.0, 3.0, 5.0 - Sampling type: The instrument gives counts per minute, or counts per liter for each optical channel - Dimensional sensitivity: 0.28 µm (50 ± 10% count efficiency)

In the framework of the SusKat (Sustainable Atmosphere for the Kathmandu Valley), ABC-UNEP and NextData Projects, CNR-ISAC and URT Ev-K2-CNR participated in the setting-up of the Kathmandu (Pakanajol) monitoring station. In particular, the station is equipped with: • meteorological sensors; • global pyranometer for downward solar short-wave radiation; • surface ozone analyzer; • optical particle counter for aerosol size distribution from 0.3 to 10 micron; • on-line PM1/PM10 analyser ; • multi-angle absorption photometer for equivalent black carbon mass measurement.

In the framework of the SusKat (Sustainable Atmosphere for the Kathmandu Valley), ABC-UNEP, SHARE and NextData Projects, CNR-ISAC and URT Ev-K2-CNR participated in the setting-up of the Kathmandu (Pakanajol) monitoring station. In particular, the station is equipped with: • meteorological sensors; • global pyranometer for downward solar short-wave radiation; • surface ozone analyzer; • optical particle counter for aerosol size distribution from 0.3 to 10 micron; • on-line PM1/PM10 analyser ; • multi-angle absorption photometer for equivalent black carbon mass measurement.

The Model 205 Ozone Monitor makes use of two detection cells to improve precision, baseline stability and response time. In the Dual Beam instrument, UV light intensity measurements Io (ozone-scrubbed air) and I (unscrubbed air) are made simultaneously. Combined with other improvements, this made it possible to reduce the time between ozone measurements to 2 seconds, making our instrument the fastest UV-based ozone monitor on the market, while still retaining the small size, weight and power requirements of our popular Model 202 Ozone Monitor.

Aerosol mass and the absorbing fraction are important variables, needed to constrain the role of atmospheric particles in the Earth radiation budget, both directly and indirectly through CCN activation. In particular, their monitoring in remote areas and mountain sites is essential for determining source regions, elucidating the mechanisms of long range transport of anthropogenic pollutants, and validating regional and global models. Since March 2006, aerosol mass and black carbon concentration have been monitored at the Nepal Climate Observatory-Pyramid, a permanent high-altitude research station located in the Khumbu valley at 5079 m a.s.l. below Mt. Everest. The first two year averages of PM1 and PM(1-10) mass were 1.94 µg m-3 and 1.88 µg m-3 , with standard deviations of 3.90 µg m-3 and 4.45 µg m-3, respectively, while the black carbon concentration average is 160.5 ng m-3, with a standard deviation of 296.1 ng m-3.Both aerosol mass and black carbon show well defined annual cycles, with a maximum during the premonsoon season and a minimum during the monsoon. They also display a typical diurnal cycle during all the seasons, with the lowest particle concentration recorded during the night, and a considerable increase during the afternoon, revealing the major role played by thermal winds in influencing the behaviour of atmospheric compounds over the high Himalayas. The aerosol concentration is subject to high variability: in fact, as well as frequent “background conditions” (55% of the time) when BC concentrations are mainly below 100 ng m-3 , concentrations up to 5 µg m-3 are reached during some episodes (a few days every year) in the premonsoon seasons.The variability of PM and BC is the result of both short-term changes due to thermal wind development in the valley, and long-range transport/synoptic circulation. At NCO-P, higher concentrations of PM1 and BC are mostly associated with regional circulation and westerly air masses from the Middle East, while the strongest contributions of mineral dust arrive from the Middle East and regional circulation, with a special contribution from North Africa and South-West Arabian Peninsula in post-monsoon and winter season.