At the Nepal Climate Observatory - Pyramid, aerosol total and back scattering coefficients at three wavelengths (450, 550 and 700 nm) are derived by an integrating nephelometer (model TSI 3563).

Optical Particle Counter - Dust Monitor 190 GRIMM determining size distribution for particles with diameters ranging between 25 nm and 32 µm.

25 Halocarbons[pptv] relevant for climate issues will be analysed in grab samples collected weekly. The following compounds are currently observed and analysed : - Halons H-1301, H-1211 - CFCs: CFC-11, CFC-12, CFC-113, CFC-114, CFC-115 - HCFCs: HCFC-22, HCFC-141b, HCFC-142b, HCFC-124 - CH3Cl, CH3Br, CH3I, CH2Cl2, CHCl3, CH3CCl3,CCl4, TCE, PCE - HFCs:HFC-134a, HFC-152a, HFC-125

The Nepal Climate Observatory - Pyramid (NCO-P, 27.95 N, 86.82 E; 5079 m a.s.l.) is located in the southern Himalayan region at the confluence of the secondary valley of Lobuche (oriented NNW-SSE) and the main Khumbu Valley. The station was placed not far from the Pyramid International Laboratory/Observatory and in proximity of the Mt. Everest base camp. All the instrumentation is housed in a wood and aluminium shelter consisting of two rooms, one for the instruments and a smaller one where batteries for the power supply are stored. The power needed to carry out the experimental activity (~ 3 kW) is provided by 96 photovoltaic panels with 120 electric storage cells. Through the aluminium roof, four sampling lines allow the sampling of gases and aerosol particles. In July 2010 the NCO-P was upgraded to GAW Global Station.

PM is measured using the optical particle counter (OPC GRIMM 190), which measures the size distributions for particle with diameters greater than 0.25 up to 32µm by means of 90° laser light scattering. The Aerosol number concentration measurement is a subset of core variables that are recommended by the GAW Scientific Advisory Group on Aerosols for long-term measurements in the global network.

At the Nepal Climate Observatory - Pyramid a UV-absorption analyser (Thermo TEI 49C UV analyzer) is used for measurement of surface ozone adopting the sampling procedures suggested within the GAW-WMO (GAW, 1992).

The instrument installed at NCOP for the study of chemical and isotopic composition of precipitation has these characteristics: Name:MTX Model: Wet_only Oriface_Height: 82.5 cm (0.825 m) LAB_INSTRUMENT Analysis_Method: IC Name: Dionex Model: ICS 2000 Number:: AS 50 Analysis_Method: IC Name:Dionex, Model:LC 25 Number: EG 40,ED 50, GS 50, AS 50 Analysis_Method: Spectrophotometer (UV/VIS) Name: PerkinElmer Model: Lambda 25 UV/VIS Spectrometer

At the Nepal Climate Observatory - Pyramid a UV-absorption analyser (Thermo TEI 49C UV analyzer) is used for measurement of surface ozone adopting the sampling procedures suggested within the GAW-WMO (GAW, 1992).

Measurements of aerosol-size distributions at the NCO-P (or Nepal Climate Observatory at Pyramid) site were continuously performed by using the scanning mobility particles sizer (SMPS) technique.

Measurements of aerosol-size distributions at the NCO-P (or Nepal Climate Observatory at Pyramid) site were continuously performed by using the scanning mobility particles sizer (SMPS) technique. The dataset is available at http://www.rrcap.unep.org/abc/data/abc/index.html.