This sensor measures:

-incoming and out outcoming far infrared radiation (W/m2) up and down Kipp & Zonen CNR1 pyrgeometer.

Forni is the largest Italian valley glacier (c. 12 km2 of surface area in the Ortles-Cevedale group, Stelvio National Park, Lombardy Alps). The glacier presents a North aspect and an elevation range between 2600 and 3670 m a.s.l. The AWS here located (named AWS1 Forni) has been set up on the ablation tongue at the WGS84 coordinates 46° 23’ 56.0” N, 10° 35’ 25.2” E, 2669 m (ellipsoidal elevation) at the base of the Eastern icefall. The AWS location is a good compromise between the needs for minimizing local topography effects and lowering the probability of avalanches destroying the AWS. The AWS 1 Forni is built around a 20 channels LSI-Lastem Babuc ABC datalogger similar to those currently deployed in the Ev-K2-CNR Himalayan monitoring network, including the 5050 m a.s.l. AWS at the Italian “CNR Pyramid Laboratory” in the Mount Everest area. The AWS Forni Glacier has been running since the 26-09-2005. The AWS is equipped with sensors for measuring air temperature, relative humidity, air speed and velocity, barometric pressure, incoming and reflected solar radiation in the 0.3 - 3 µm spectral range and far infrared radiation in the 5 - 50 µm range from the sky and from the glacier surface (four-components Kipp & Zonen CNR-1 net radiometer). A 1000 cm2 unheated rain gauge and a Campbell SR-50 sonic ranger are also present to measure rain and snow level respectively. In order to allow triggering of the SR-50 sonic ranger by the Babuc ABC datalogger, as well as to input the digital readout of the snow level, we designed and built a custom digital interface suitable for low temperatures operation. This was necessary since the Babuc ABC is only equipped with a proprietary serial interface for which specifications were not readily available. Furthermore, voltage levels, pulse length and rise times which can be output from the Babuc ABC’s actuator sockets are neither compatible with the Campbell SR-50 nor programmable, at least within the required tolerances. These parameters also showed to be very sensitive both to battery voltage and to ambient temperature, which is normal when considering their intended purpose of supplying power to external devices. Our interface allowed to correctly shape the trigger pulse for initiate the snow level measurement, as well as to acquire the serial pulse train output from the SR-50 through a spare datalogger input meant for rain gauge connection. Power is supplied by two solar panels rated for 40W of combined nominal power and backed-up by a 100 Ah 12 V lead-gel battery; the battery voltage over time is recorded by the datalogger. Spare datalogger inputs, as well as power and data storage capability are available to support additional devices such as further temperature and relative humidity sensors at various heights above ground and a GSM modem. Estimated battery-only power supply in the present configuration is estimated in excess of two months, with the solar panels permanently obscured by snow accumulation and accounting for low temperatures operation and self discharge. Data storage takes place in a hot-swappable 2 Mbytes flash memory card capable of a more than 6 months-long record. The whole system is supported by a four legs, 5 m high stainless steel mast standing on the ice surface according to the construction proposed and tested by IMAU. This sensors suite allows evaluating the actual suitability of the selected location and the overall system performance over wintertime conditions. The scientific partners of Forni Projects are: EV-K2-CNR Bergamo, AEM Milano, Arpa Lombardia, CAI Alpine Rescue Service (Bormio and Valfurva stations).

The CNR1 net radiometer by Kipp & Zonen is for applications requiring research-grade performance. The radiometer measures the energy balance between incoming short-wave and long-wave IR radiation versus surface-reflected short-wave and outgoing long-wave IR radiation. The CNR1 consists of a pyranometer and pyrgeometer pair that faces upward and a complementary pair that faces downward. The pyranometers and pyrgeometers measure short-wave and far infrared radiation, respectively. The CNR1 also includes an RTD to measure the radiometer’s internal temperature and a heater that can be used to prevent condensation.

CNR1 Specifications

Sensors: Kipp & Zonen’s CM3 ISO-class, thermopile pyranometer, CG3 pyrgeometer, PT100 RTD

Spectral Response

Pyranometer: 305 to 2800 nm

Pyrgeometer: 5000 to 50,000 nm

Response Time: 18 seconds

Sensitivity Range: 7 to 15 ?V W-1 m2

Output Range

Pyranometer: 0 to 25 mV

Pyrgeometer: ±5 mV

Expected Accuracy for Daily Totals: ±10%

Directional Error: <25 W m-2 (pyranometer)

Heating Resistor: 24 Ohms, 6 W at 12 Vdc

CE Compliance: CE compliant under the European Union’s EMC directive