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Everest - Pyramid
-O3-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
Local time +5:45 |
| Sampling |
| Sampling height |
: |
3.8 |
| Description |
: |
continuous |
| Sampling and analysis frequency |
: |
Continuous |
| Sampling environment |
: |
The Everest - Pyramid station, 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. The power needed to carry out the experimental activity (~ 3 kW) is provided by 96 photovoltaic panels with 120 electric storage cells (no local source of contamination).
The nearest village (very small) is located down the valley at about 1.5 km from the measurement site.
No access by road. |
| Description for sampling analysis |
: |
The air is sampled by a 1m long intake at 3.5 m height above
the ground. The air intake is a inox-steel pipe passivated for ozone.
A Teflon sampling line (lenght 1.5m) connects the air intake with the analyser. |
| Instrument and Analysis |
| Measurement method |
: |
Light absorption analysis (UV) |
| Current status and history of instrument |
: |
Thermo Environmental - Model 49C (S/N 0525712879): March 2006 - May 2009
Thermo Environmental - Model 49i: May 2009 - October 2009 (temporary back-up analyser)
Thermo Environmental - Model 49C (S/N 0525712879): October 2009 - November 2011
Thermo Environmental - Model 49i: November 2011 - April 2012 (temporary back-up analyser)
Thermo Environmental - Model 49C (S/N 0525712879): April 2012 - ongoing |
| Description of instrument |
: |
Range (as declared by Manufacturer): 0-0.5 to 1.0 ppm
Lower detectable limit (as declared by Manufacturer):1.0 ppb
Precision (as declared by Manufacturer): 1 ppb
Zero drift (as declared by Manufacturer): <1ppb/24hour; <2ppb/7day
Span drift (as declared by Manufacturer): less than 1% per month
Linearity: +/- 1% Fullscale |
| Calibration |
| Current scale employed in the measurement |
: |
SRP#15 (hosted at EMPA-WCC) |
| Measurement calibration |
: |
Multipoints calibration are systematically performed for the working analyser (see Scale and Calibration).
Zero and span checks are performed every 24 hours, automatically. |
| Scale and calibration(treasability) |
: |
On February 2007 and April 2011, the working analyzer (Thermo Environmental Corp. Model 49C, S/N 0525712879) has been compared in-situ against a transfer standard (TEI 49C-PS #56891-310) provided by the GAW World Calibration Centre for surface O3 (WCC-EMPA).
On April 2009, the working analyzer (Thermo Environmental Corp. Model 49C, S/N 0525712879) has been compared in-situ against a transfer standard (Sycos KT03, ANSYCO).
On September 2009 and February 2012, the working analyzer (Thermo Electron Corporation, Model 49C, S/N 0525712879) has been compared against the ozone primary standard SRP#15 at the GAW World Calibration Centre for surface O3 (WCC-EMPA).
On November 2009 and November 2011, the temporary back-up analyser (Thermo Environmental Corp. Model 49i) has been compared against a transfer standard (TEI 49C-PS #77309-385) at the manufacturer laboratory (TESS-COM Italia s.r.l.). |
| Data Processing |
| Measurement unit |
: |
ppbv |
| Data processing |
: |
Raw data from monitoring device are acquired every minute and validated to obtain 1 hour mean values. |
| Processing for averaging |
: |
Processing for Hourly Data:
Raw 1-minute data are validated also inspecting internal instrument parameters (i.e. cell flows, lamp intensities, internal pressure, bench and lamp temperatures), 24 hour and monthly zero/span drifts and concurring meteorological and aerosol on-line measurements.
Automated statistical checks are applied to point out outliers data.
Hourly data here submitted are obtained by averaging 1-minute validated data.
Processing for Daily Data:
From 2006 to 2010 simply averaging from hourly data by WDCGG. From 2011, daily values are calculated by averaging hourly data if less than 25% of hourly points are missing.
Processing for Monthly Data:
From 2006 to 2010 simply averaging from daily data by WDCGG. From 2011, monthly values are calculated by averaging daily data if less than 25% of daily points are missing. |
| Data flag |
: |
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| Data remarks |
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| Other Information |
| Scientific aim |
: |
Investigation of background troposphere conditions
Investigation of regional and long-range pollution
Investigation of stratospheric intrusion events
Model validations |
| Reference |
: |
P. Cristofanelli, A. Bracci, M. Sprenger, A. Marinoni, U. Bonafè, F. Calzolari, R. Duchi, P. Laj, J.M. Pichon, F. Roccato, H. Venzac, E. Vuillermoz, and P. BonasoniTropospheric ozone variations at the Nepal Climate Observatory-Pyramid (Himalayas, 5079 m a.s.l.) and influence of deep stratospheric intrusion events. Atmos. Chem. Phys., 10, 6537-6549, 2010.
P. Bonasoni, P. Laj, A. Marinoni, M. Sprenger, F. Angelini, J. Arduini, U. Bonafè, F. Calzolari, T. Colombo, S. Decesari, C. Di Biagio, A. G. di Sarra, F. Evangelisti, R. Duchi, MC. Facchini, S. Fuzzi, G. P. Gobbi, M. Maione, A. Panday, F. Roccato, K. Sellegri, H. Venzac, GP. Verza, P. Villani, E. Vuillermoz, and P. Cristofanelli. Atmospheric Brown Clouds in the Himalayas: first two years of continuous observations at the Nepal Climate Observatory-Pyramid (5079 m). Atmos. Chem. Phys., 10, 7515-7531, 2010
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| submitted by National Research Council, Institute of Atmospheric Sciences and Climate |
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