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NO 51
Acronym VNMHA
Name Viet Nam Meteorological and Hydrological Administration
Address 1
Address 2
Address 3 No. 8 Phao Dai Lang street 100000 Ha Noi Viet Nam
Country/Territory Viet Nam
Website http://kttvqg.gov.vn


Name Nguyen Nhat Anh
Email anhnnhn@gmail.com
Organization No 51
Organization acronym VNMHA
Organization name Viet Nam Meteorological and Hydrological Administration
Organization country/territory Viet Nam
Address 1 No. 8 Phao Dai Lang street
Address 2 100000 Ha Noi
Address 3 Viet Nam
Country/territory Viet Nam
Tel +84905881618
Last updated date 2020-07-13

Name Martin Steinbacher
Prefix Dr.
Email martin.steinbacher@empa.ch
Organization No 23
Organization acronym Empa
Organization name Swiss Federal Laboratories for Materials Science and Technology
Organization country/territory Switzerland
Address 1 Ueberlandstrasse 129
Address 2 CH-8600 Duebendorf
Address 3 Switzerland
Country/territory Switzerland
Tel +41 58 765 4048
Fax +41 58 765 1122
Last updated date 2020-08-28

NO 23
Acronym Empa
Name Swiss Federal Laboratories for Materials Science and Technology
 Background observation
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: WMO CO X2004
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: Picarro Inc., G2401, S/N CFKADS2028(CRDS)
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: 12 (m)
 1 second
 The analyzer is regularly calibrated with four reference gases. All assigned mole fractions are reported on the WMO CO X2004 scale. The quality of the calibration is verified with a fifth reference gas (target cylinder).
Four calibration tanks are measured every 3 to 6 days. Two of them are tanks purchased from and pre-pared by the GAW Central Calibration Laboratory for CO (NOAA ESRL). The other two calibration gas-es are prepared by Empa (Switzerland) and their mole fractions were determined by the GAW World Calibration Centre for CH4, CO2, CO and surface O3 (WCC-Empa). WCC-Empa also assigned the mole fractions of an additional target cylinders that is measured every 25 hours for quality control.
 Quality assurance procedures involve time series plots, target tank (i.e. cylinders containing natural air with assigned gas mole fractions that are treated as (unknown) sample in a sequence of analyses) measurements, evaluation of the evolution of the instrument sensitivity, and consistency checks. The measurements were made in humid air, and a water vapour correction was applied.
 [Hourly] high-resolution data are aggregated to 1min averages before hourly averages are calculated. Thus, ND (the number of detections) refers to the number of available 1min averages within the respective hour. A minimum of 20 1-min averages needs to be available to calculate hourly averages; otherwise, hourly data are reported as not available.
 [Daily] hourly averages are aggregated to daily means. Thus, ND (the number of detections) refers to the number of available hourly averages within the respective day. A minimum of 8 hourly averages needs to be available to calculate daily averages; otherwise, daily data are reported as not available.
 [Monthly] daily data are aggregated to monthly means. Thus, ND (the number of detections) refers to the number of available daily averages within the respective month. A minimum of 10 daily averages needs to be available to calculate monthly averages; otherwise, monthly data are reported as not available.
 Pha Din is located on a hill in north-western rural Viet Nam above the surrounding forests.
Population: No residents at the station except for the custodians. No relevant residential areas within 10-20 km, except for sparse individual farm houses. The closest farm house is located in 1 km distance in NE direction.
Land cover: Mountain hill area covered with forest. The station itself is above the canopy.
Possible influence of local and regional emissions: Occasional corn plant burning in March and April. Staff housing (gas cooking, electrical heating, occasional trash burning) is at the station. No coal power plants and other industrial activities in the region.
Prevailing wind directions: NE in winter and SW in summer.
Temperature: 25-30 ºC in summer and down to 3 ºC in winter. No snow or ice in winter.
Rainfall and humidity: The site is in clouds a considerable fraction of the year with a correspondingly high relative humidity all year long.
Access: Pha Din is reachable all year long via a paved mountain road (8 h by car from Ha Noi city via Son La). After heavy rainfalls the roads may be blocked due to landslides.
Facilities: The station represents a Level 3 NHMS meteorological station since September 2011 provid-ing manual readings every 6 hours for wind and wind speed. The laboratory building provides air-conditioned laboratory space and also basic accommodation for station operators and guest research-ers. The station is permanently occupied with 3 staff persons.

CO observations are performed with a commercially available instrument (Picarro Inc., G2401) based on the Wavelength-Scanned Cavity Ringdown Spectroscopy technique coupled to a custom-built calibration unit. Along with CO, the instrument is also capable to measure CO2, CH4 and H2O. Thus, the CO data can be corrected for interferences of water vapor. Therefore, no drying is applied prior to analysis and CO dry air mole fractions are determined by application of an empirical humidity correction to analysis data of the fully unaltered humid gas stream accounting dilution and pressure broadening effects.
tubing material: Dekabon/Synflex 1/4" OD; total inlet length approx. 21m; flow rate into lab: 5 lpm; no drying prior to analysis; dry air mole fractions are determined by applying an empirical humidity correction (see below).

The observations are supported by the Federal Office of Meteorology and Climatology MeteoSwiss through the project Capacity Building and Twinning for Climate Observing Systems (CATCOS) between the Swiss Agency for Development and Cooperation (SDC) and MeteoSwiss.
 Wind direction:
 Wind speed:
 Relative humidity:
 Precipitation amount:
 Air pressure:
 Air temperature:
 Dew point temperature:
 Sea water temperature:
 Sea surface water temperature:
 Sea water salinity:
 Sea surface water salinity:
Meteorological data may remain as first provded, even when greenhouse gas data are updated.
1  For a short summary see Trinh Lan Phuong and Duong Hoang Long, Greenhouse gases measurements in Viet Nam, in Asia-Pacific GAW on Greenhouse Gases Newsletter vol 5, 33 - 38, 2014. available at http://www.wmo.int/pages/prog/arep/gaw/documents/The_5th_Asia_Pacifi_Newsletter_on_Greenhouse_Gases.pdf.
CO data for the 2014 to 2018 period are presented in
Bukowiecki N., M. Steinbacher, S. Henne, N. A. Ngyuen, X. A. Ngyuen, A. L. Hoang, D. L. Ngyuen, L. H. Duong, G. Engling, G. Wehrle, M. Gysel-Beer, U. Baltensperger, 2019. Effect of Large-scale Biomass Burning on Aerosol Optical Properties at the GAW Regional Station Pha Din, Vietnam, Aerosol and Air Quality Research, 19 1172–1187, doi: 10.4209/aaqr.2018.11.0406.