The USH-8 Ultrasonic Snow Depth Sensor by SOMMER is ideal for the reliable measurement of snow-depth in extreme conditions. The sensor’s principle of measurement deals with the transit-time measurement of an ultrasonic pulse. The sensor transmits several energy-charged pulses to the snow cover and subsequently receives its reflected signals. Based upon the required transit time of the ultrasonic signals, the USH-8 sensor calculates the current snow depth. The processing time of the ultrasonic pulses here is enormously influenced by the air temperature. For this reason, the snow depth sensor also possesses integrated temperature compensation. This takes into account the influence of the air temperature on the processing time of the ultrasonic signals, in the calculation of the snow depth. The calculation takes place in the sensor, so that the output signal provides the already converted snow depth. USH-8 Specifications: Snow Depth Measurement Range of measurement: 0 to 8 m Minimum distance to the maximum expected snow depth: 1 m Accuracy: 0,1 % (FS) Resolution 1 mm Principle of measurement: Ultrasonic (Frequency 50 kHz; Angle of reflected beam 12°) Integrated Compensation of the Air Temperature Temperature sensor: Integrated air-temperature sensor in self-venting radiation shield Range of measurement: -35 to 60 °C Resolution: 0,1 °C Non-linearity: ? 0,15 % Interfaces Analogue: Snow depth measurement 0/4 - 20 mA signal (configurable) Resolution: 12 Bit Max. load: 300 ? Digital: Snow depth measurement; air temperature; quality flag RS 232; serial interface Protocol: Various ASCII formats

The CNR 4 net radiometer hes been installed in Lukla in 2013 and it consists of a pyranometer pair, one facing upward, the other facing downward, and a pyrgeometer pair in a similar configuration. The pyranometer pair measures the short-wave radiation. And the pyrgeometer pair measures long-wave radiation. The upper long-wave detector of CNR 4 has a meniscus dome. This ensures that water droplets role off easily and improves the field of view to nearly 180°, compared with a 150° for a flat window. All 4 sensors are integrated directly into the instrument body, instead of separate modules mounted onto the housing. But are each calibrated individually for optimal accuracy. Two temperature sensors, a Pt-100 and Thermistor, are integrated for compatibility with every data logger. The temperature sensor is used to provide information to correct the infrared readings for the temperature of the instrument housing. Care has been taken to place the long-wave sensors close to each other and close to the temperature sensors. This assures that the temperatures of the measurement surfaces are the same and accurately known. Which improves the quality of the long-wave measurements. Technical Characteristics: Spectral range: 300 to 2800 (short wave) nm Spectral range: 4500 to 42000 (long wave) nm Sensitivity: 5 to 20 µV/W/m² Temperature dependence of sensitivity (-10 ºC to +40 ºC) : < 4 % Response time: < 18 s Non-linearity: < 1 % Operating temperature: -40 to 80 °C Ventilation power (of the optional CNF 4 ventilation unit): 10 W

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

In 2013 the Wind Set WA15 by Vaisala has been installed in Lukla. Overview • High-performance wind measurement set • Long and successful track record in meteorological applications • Low measurement starting threshold • Conical anemometer cups provide excellent linearity • Heated shaft prevents bearings from freezing Technical Specifications Wind speed Sensor / transducer type: cup anemometer / opto-chopper Measurement range: 0.4...75 m/s Starting threshold: <0.5 m/s * Distance constant: 2.0 m Accuracy (range 0.4...60 m/s) with characteristic transfer function: ±0.17 m/s ** with transfer function U=0.1xR: ±0.5 m/s Wind direction Sensor / transducer type: vane / optical code disc Measurement range: 0...360° Starting threshold: <0.4 m/s Delay distance: 0.4 m Resolution: ±2.8° Accuracy: better than ±3°

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 AWS Lukla 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

In Lukla the CX115P Lsi-Lastem barometer is connected with a measurement system (recorder, data logger) that accepts analog signals. The barometer works according to the piezometric principle: a resistive film is deposited on a slice of silica with a bridge form; as the pressure changes, the slice will deform and consequently changes the system's resistance. The CX115P model mounts a special thermal compensation system that significantly reduces drift. General characteristics: Range: 800 ž 1100 hPa (1 hPa=1 mBar) Sea level correction range: -300...+2000 mt. Thermal drift: 0,01 hPa/°C (-10..+60°C) Linearity&Hysteresis: < 0,3% of the range Overload: max. 2 Pa Load resi stance: Current output types: <500W. Power consumption: 3 W Response time (T90): 1 ms Environmental limits: -25 .. +60°C Output connections: terminals Weight: 650 gr. Housing case material: Plastic Protection: IP40 Downward cable outlet

At the AWS Askole 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...2800 nm (50%points) - Sensitivity 9...15µV/Wm-2 - Impedance 70...100 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...+90 °C - Temperature dependence of sensitivity +/- 2% (-10...+40°C) - Maximum irradiance 2000 W/m2 - Directional error <+/- 20 W/m2 at 1000 W/m2 - Weight 0.85 kg - Cable length 10