First results from a new high precision trace gas analysis system for air analysis within Brazil
John
Miller, NOAA/CMDL, john.b.miller@noaa.gov
(Presenting)
Luciana
Vanni
Gatti, LQA/IPEN, lvgatti@net.ipen.br
Andrew
Crotwell, NOAA/CMDL, Andrew.crotwell@noaa.gov
Pieter
Tans, NOAA/CMDL, pieter.tans@noaa.gov
Paulo
Artaxo, Institute of Physics, USP, artaxo@if.usp.br
Monica
Tais Siqueira
D'Amelio, LQA/IPEN, monicatais@yahoo.com
Since December 2000 we have measured vertical profiles of CO2, CH4, CO, H2, N2O, SF6, δ13C and δ18O above Santarem and Fortaleza. Samples are collected aboard light aircraft between the surface and either 4 km (Santarem) or 5 km (Fortaleza) using the NOAA/CMDL portable flask package (PFP). The PFP’s are sent from Boulder, Colorado to Brazil, where they are filled, and then sent back to Colorado for analysis.
Starting in May 2004, non-isotopic species from these samples will be measured routinely in Brazil. This change in strategy was necessary to increase the frequency of measurements, which was severely hampered due to problems inherent in shipping samples between Brazil and the United States. In order to accomplish this, Dr. Luciana Gatti from IPEN visited NOAA during July and August of 2003 to begin the process of building a replica of the NOAA/CMDL trace gas analysis system. That system was completed in 2003 and recently arrived in Brazil where it will soon be installed. During tests of the system at NOAA, the precision of measurements obtained met or exceeded those of the original system. Specifically, the analytical precision is as follows: CO2, 0.03 ppm; CH4, 1.5 ppb; CO, 1.3 ppb; H2, 1.3 ppb; N2O, 0.17 ppb; SF6, 0.03 ppt.
Perhaps more important than the high analytical precision is the fact that the system is designed around rigorous calibration of all measurements to references directly traceable to the scales used by NOAA/CMDL. This helps to ensure that all the measurements made by the new Brazilian system will be compatible with the existing NOAA/CMDL measurements. As extra levels of quality control, the two labs will regularly measure air collected at the same time and the system in Brazil will routinely analyzed air from a high-pressure “surveillance” tank. This tank is a reference tank with known values for all trace gases that will be treated as an unknown, so that any systematic errors can be identified. The final step in our plan to have all species analyzed in Brazil will be to have PFP’s analyzed for isotopic ratios at USP/CENA, transferring technology from the University of Colorado, Stable Isotope Laboratory. We hope to start this by the end of 2004. Analyzing samples in Brazil and thus avoiding import and export of PFP’s should allow us to dramatically increase the frequency of our measurements.
Submetido por John Bharat Miller em 26-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)