The second calibration campaign at Everest-Pyramid station
BOLOGNA -- After the installation of the Everest-Pyramid ABC-GAW Station at 5079 m asl, along the Khumbu Valley, in February 2006, the station is quite automatically running. A technical check of instruments and quality assurance of data are guaranteed by remote access of every instrument and acquisition system (from Italy and France), but also thanks to Nepalese staff present 365 days per year at Pyramid Laboratory.
A more detailed check of the whole instrumentation, with an accurate calibration of each device, at least once per year is necessary anyway. This year I was in charge of the second calibration campaign, together with Paolo Villani (an engineer of OPGC-France) Elisa Vuillermoz and GianPietro Verza (Technical Assistants of Ev-K2-CNR Committee). This duty was not only a simple job, was a great opportunity to experience very special life moments.
I was part of a similar experience 10 years ago, in fact I participate to another campaign at Pyramid Laboratory and it was really interesting to observe changing in tradition and culture of such enchanting people, as sherpa people are. Actually, even if the Khumbu Valley appears more and more crowed by people and houses, luckily Sherpa people didn’t lose their smiling face in any condition and situation (even below hundred kilos of load!). In fact Lobuche, the village where Pyramid is located, is 5 days trek far from last place reachable by any way of transport. And this offers a very special opportunity to enjoy Nepal and its territory.
The calibration campaign lied 15 days of work at Pyramid Laboratory. Each Instrument was dismounted, brought down from the Everest-Pyramid station to the Pyramid Laboratory, were it was cleaned, checked and regulated. First of all we have taken maintenance service for the instruments that presented failures: nephelometer and optical particle counter. Reparation of these instruments consist in replacement of two damaged spare parts: air pump for OPC and motor shutter for nephelomenter. For the whole instrumentation we measured every air flow rate, electric signal and noise level. We determine the detection limit and noise level with a zero filter during at least 12 hours of measurement. For the modified instrument we performed these operation before and after modifications, in order to check if modifications were invading on the measure. For the aerosol monitors in addition to concentration we calibrated the diameter detected by each instrument with special latex particles with a certified diameter (100, 400 and 3000 nm).
The calibration campaign was successful for quite every instrument confirming the good quality of data collected during last year by Everest-Pyramid station.
During the field campaign scientists present at Pyramid had the opportunity to assist to a real time pollution transport: in fact on 10th February 2008 at 11 AM a simultaneous strong and rapid increase of ozone, black carbon and accumulation particles mass was observed, together with a haze rising from Khumbu Valley and clearly visible by people at Pyramid. GianPietro with local Pyramid staff hold an investigation on what happened in the valley and they put in relation the pollution recorded (see graph below) at Everest-Pyramid with a grass fire started two hour before and few tenths of kilometres to the South of the Regional GAW Everest-Pyramid station and more than one kilometer lower. The positive correlation between black carbon and surface O3 values confirm the transport of photochemical polluted air masses to the Station.
Angela Marinoni