TG-06 Abstract

Vertical Profiles of Carbon Dioxide and Other Trace Gas Species Over the Amazon Basin Using Small Aircraft
Paulo Artaxo, USP (SA-PI)
Peter S. Bakwin, NOAA/CMDL (US-PI)
Luciana Vanni Gatti, IPEN - Instituto de Pesquisas Energeticas eNucleares (SA-PI)
Luiz Antonio Martinelli, CENA/USP (SA-PI)

We propose to continue measurements, as part of LBA-ECO, of the vertical profiles of several atmospheric trace gas species and isotope ratios, and to develop a capability in Brazil for long-term measurements of trace gases and CO2 isotopes that does not currently exist.  On flights using small charter aircraft over the Santarém Tapajos tower site, and over the Atlantic Ocean off the coast of Fortaleza, we will measure the mixing ratios of CO2, CO, CH4, N2O, H2 and SF6, the 13C/12C and 18O/16O isotopic ratios in CO2, and the 13C/12C ratio in CH4 in flask samples collected automatically up to an altitude of about 4 km.  As they are available, we will use NASA, INPE or other research aircraft to obtain samples at higher altitudes and other locations.  Flask samples collected over the Atlantic Ocean and over the forest in the central Amazon basin will enable us to quantify the change in trace gas mixing ratios and isotopic composition during the transit of air across the basin.  Other areas will be sampled on a campaign basis, in coordination with other LBA and Brazilian studies, primarily to examine the isotopic signature of CO2 exchange in other ecosystem types.

Initially the flasks will be analyzed in our laboratories in Boulder using existing equipment.  In the first year of this renewal we will develop the capacity to carry out the trace gas analyses in the Brazilian laboratories at IPEN, and in the second year we will upgrade existing equipment at CENA (Universidade de São Paulo) for measurements of 13C/12C and 18O/16O in CO2 in the flask samples.  Doing the analyses in Brazil will alleviate very serious problems we have had so far with shipping into and out of Brazil, particularly with Brazilian Customs, and will lead to long-term cost savings.  Also, this will provide the expertise for long-term observations in Brazil that can be integrated into the global observing network for these trace gases and isotopes, and can be used in other measurement campaigns.  All species mixing ratios and isotopic ratios will be firmly tied to internationally accepted calibration scales.  The observations will constitute the first multi-year time series of CO2, CH4 and N2O mixing ratios, and CO2 isotopic composition, over the Amazon region.  Measurements of SF6 will give a sensitive indicator for penetration of northern hemisphere air into the study area.  The data will provide an important constraint for regional and global models of these trace gases, and an independent estimate of regional exchange for validation of scaling of observations from the flux towers to the whole LBA study area.  In addition, the payload requirements for our equipment are modest, approximately 60 kg, and our aircraft flights could be a useful resource for other investigators in LBA.

Our work includes a Training and Education component that is focused on establishing infrastructure so that all trace gas and isotope analyses will be done by Brazilian laboratories.  For long-term (beyond LBA) monitoring in Brazil this is clearly needed for both logistical and political reasons.  It is very important that we develop solid calibrations for the measurements made in Brazil and maintain on-going intercomparison and data exchange between the US and Brazilian laboratories.