The purpose of the present work was to investigate variations in the surface areas of lakes in the north-east sector of Sagarmatha National Park (Nepal) at the end of the 20th century, through comparison of the Mount Everest maps based on a survey done in the early 1980s, and the official Map of Nepal based on a survey done at the beginning of the 1990s. The analysis of the changes occurring between the 1980s and the 1990s in the surface areas and distribution of lakes in the north-east sector of SNP reveals that lake areas substantially increased, by 15.4 (-5.5; +5.7)% (median 12.5%), within hydrographic basins that included a certain amount of glacial cover. In fact, 96% of the lakes whose surface area increased are located in glacial basins. Conversely, the majority of the lakes without glacial cover in their catchment showed a reduction in surface area, and in many cases disappeared (83% of the lakes that disappeared were situated in basins without glaciers). This different behaviour of these two types of lakes, though observed over a short time span, would appear to be consistent with the consequences of temperature increases recorded from the beginning of 1980s on a global and local scale. The digital tool produced (Limnological Information System, LIS) as part of this work is intended to provide a useful platform for extending the analysis to entire area of SNP, as well as for subsequent comparisons based on earlier maps or more recent satellite images.

At the AWS Pheriche station the CM6B Kipp&Zonen pyranometer is installed. It is mounted on a 2m pole. The CM6B is a first class pyranometer as defined by the World Meteorological Organization. It is suitable for the measurement of solar irradiance on a plane surface (W/m2). It incorporates a 64-thermocouple sensor, which is rotationally symmetrical, housed under K5 domes. A white screen prevents the body of the pyranometer from heating up. The pyranometer is supplied with a spirit level and screws for accurate levelling. A drying cartridge keeps the interior free from humidity. The technical characteristics are: - Spectral range: 305 to 2800 nm (50%points) - Sensitivity: 9 to 15µV/Wm-2 - Impedance: 70 to100 Ohm - Response time: 1/e 5 s, 99 % 55 s - Non-linearity: <1.5 % (<1000 W/m2) - Tilt error: <1.5 % at 1000 W/m2 - Operating temperature: -40 to +90 °C - Temperature dependence of sensitivity +/- 2% (-10 to +40°C) - Maximum irradiance 2000 W/m2 - Directional error: <+/- 20 W/m2 at 1000 W/m2 - Weight: 0.85 kg - Cable length: 10

At the AWS Namche station the DQA035 Lsi-Lastem rain gauge is mounted on a 1,5 m mast. This model of Rain gauge has a 1.000 cmq collector area. The measurement device is composed of a collector cone and a double chamber bascule connected to a magnete that operates one (optional two) reed switch, which generates impulses that can be counted by external meters: each impulse is equal to 0.2 mm of rain (optional from 0.1 to 0.5 mm). The mechanical and electrical specifications are: - Collector surface area: 1000 cmq - Collector area diameter: 420 mm - Measurements range: 180 mm/hr - Resolution: o,2 mm/imp. (opt. 0,1; 0,3; 0,4; 0,5; mm/imp.) - Accuracy: 0-1 mm/min: 1% 1-3 mm/min: 2% 3-5 mm/min: 4% 5-10 mm/min: 8% - Contact: 1 reed (opt. N.2 reed) 0,5 A/24V non inductive - Pulse duration: 100 msec.± 5 - Collector cone material: Brass - External housing material: Inox AISI30 - Tipping bucket material: Alluminium - Cable: 10 m - Weight: 6,3 kg - Power supply: /thermocover 100 W, 24 Vca/Va

At the Lukla station the the CM6B pyranometer, manufactured by Kipp & Zonen is installed. This sensor is a first class pyranometer as defined by the World Meteorological Organization. It is suitable for the measurement of solar irradiance on a plane surface (W/m2). It incorporates a 64-thermocouple sensor, which is rotationally symmetrical, housed under K5 domes. A white screen prevents the body of the pyranometer from heating up. The pyranometer is supplied with a spirit level and screws for accurate levelling. CM6B technical data - Spectral range 305 to 2800 nm (50%points) - Sensitivity 9 to 15 ?V/Wm-2 - Impedance 70 to 100 Ohm - Response time 1/e 5 s, 99 % 55 s - Non-linearity <1.5 % (<1000 W/m 2 ) - Tilt error <1.5 % at 1000 W/m 2 - Operating temperature -40 to +90 °C - Temperature dependence of sensitivity _2 % (-10 to +40 °C) - Maximum irradiance 2000 W/m2 - Directional error < _20 W/m2 at 1000 W/m2 - Weight 0.85 kg - Cable length 10 m

Since 2014, the Digital Barometer PTB330, by VAISALA, is installed. Vaisala BAROCAP® Digital Barometer PTB330 is a new generation barometer, designed for a wide range of high-end atmospheric pressure measurement. -Vaisala BAROCAP® sensor -Accurate measurement -Excellent long-term stability -Added reliability through redundancy -Graphical trend display with 1-year history data -Altitude corrected pressure (QFE, QNH) -For professional use in meteorology, aviation, laboratories, and demanding industrial applications

At the AWS Pheriche station the DQA035 Lsi-Lastem rain gauge is mounted on a 1,5 m pole. This model of Rain gauge has a 1.000 cmq collector area. The measurement device is composed of a collector cone and a double chamber bascule connected to a magnete that operates one (optional two) reed switch, which generates impulses that can be counted by external meters: each impulse is equal to 0.2 mm of rain (optional from 0.1 to 0.5 mm). The mechanical and electrical specifications are: - Collector surface area: 1000 cmq - Collector area diameter: 420 mm - Measurements range: 180 mm/hr - Resolution: o,2 mm/imp. (opt. 0,1; 0,3; 0,4; 0,5; mm/imp.) - Accuracy: 0-1 mm/min: 1% 1-3 mm/min: 2% 3-5 mm/min: 4% 5-10 mm/min: 8% - Contact: 1 reed (opt. N.2 reed) 0,5 A/24V non inductive - Pulse duration: 100 msec.± 5 - Collector cone material: Brass - External housing material: Inox AISI30 - Tipping bucket material: Alluminium - Cable: 10 m - Weight: 6,3 kg - Power supply: /thermocover 100 W, 24 Vca/Va

The Win-Situ multiparametric probe TROLL 9500 (Water level, water temperature, water conductivity and turbidity) was installed on 2nd July 2012 with the aim of providing a general assessment of quantity and quality of the running water network in Sagarmatha National Park (Dud Koshi basin) with a special focus on the evaluation of the climate change (CC) occurred at local and region level and its possible effects on water availability. From August 2014 the station is powered with photovoltaic system. Geographical coordinates: Latitude: 27° 53' 0.4" N Longitude: 86° 49' 6.3” E Elevation (m): 4222 Water Level: - Accuracy: ±0.05% FS; Range: 15 psi Water temperature: - Accuracy::±0.1°C; Range:-5°C ÷ +50°C; Methodology: EPA 170.1 Conductivity: -Accuracy::±5%; Methodology: Std.Mthds. 2510, EPA 120.1 Turbidity: -Accuracy::±5% or 2 NTU; Range:0 NTU ÷ 2000 NTU; Methodology: ISO 7027

At the AWS Pheriche station the CombiSD DNA022 Lsi-Lastem combined wind speed-direction sensor is mounted on a 5m pole. The CombiSD sensor includes, in a single apparatus, the both transducers for measuring wind speed and wind direction. Its use simplifies the installation and the plant design in respect of the sensors with separate measurements plus giving some other advantages being smaller, lighter and cheaper. The CombiSD DNA022: sensor has a direct signal output. Frequency (Hz) for wind speed and resistance (Ohm) for wind direction. the CombiSD has low power consumption, it can be used in systems with small energy availability. The technical characteristics are: - Principle of operation: 3 cups and vane anemometer - Speed sensor: Optoelectronic disk - Direction sensor: 2000 Ohm wire potentiometer / Positioning Hall effect sensor - Housing: Heavy gauge anodised aluminium - Shaft carriers: Low-torque stainless steel bearings - Protection (vertical position): IP65 - Mechanical mounting: On 48 50 mm diameter mast - Electrical outlet terminators: IP65 watertight connector - Weight (instrument with rotors): 950 gr. The Physical and operational specification are: - damage threshold > 75 m/s - operating temperature: -30°+70°C The speed measures are specified by: - Measurement range: 0-60 m/s (using transfer function) - Threshold: 0,21 m/s - Response time (63% at 5 m/s): 0.8 s - Distance constant (delay distance) at 5 m/s: 4 m - Resolution (integration time=1s): 0.05 m/s - Accuracy & Linearity: 0,1 m/s+1%VL (readout), if connected to LASTEM data loggers. The direction measures are specified by: - Measurement range: 0 ÷ 360 - Threshold: 0,15 m/s - Response time (at 5 m/s): 0,26 s - Delay distance (at 5 m/s): 1,32 m - Damping coefficient (VDI3786): 0,21 - Transfer function: Dir(°)= 355 x R(Ohm)/2000 - Resolution: 0,1 - Accuracy: 1% FS (Full scale) - Integral linearity: 0,5%