BACKGROUND IN GREENHOUSE GASES BRAZILIAN

NORTHEASTERN COAST BORGES, V.F.1, GATTI, L.V.1, MARTINEWSKI, A.1, CORREIA, C.S.C.1, BASSO, L.S.1,

DOMINGUES, L.G.1, GLOOR, E.2, MILLER, J.B.3 The 16th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases, and Related Measurement Techniques (GGMT)

25 - 28 October 2011, Wellington, New Zealand

1 - Instituto de Pesquisas Energéticas e Nucleares – IPEN/USP, São Paulo, Brazil; 2 - University of Leeds, Leeds, United Kingdom; 3 - National Oceanic and Atmospheric Administration – NOAA, Boulder, Colorado, USA. lvgatti@gmail.com

The absence measures on the tropics and the Amazon, generate a significant

uncertainty in the models obtained because there are no measures that represent

the contribution of these areas. Since Brazil is a tropical country and has one of

the world's major rainforests, the Amazon, accounting 50% of this biome on the

world, is important to understand it as a source or sink of greenhouse gases to

climate predictions. The objective of this study is to determine the background of

greenhouse gases that arrive on the Brazilian coast, from the Atlantic Ocean, in a

band that corresponding to the Amazon Basin.

The mean concentrations found were: SAL (since Jan-10 until Aug-11) –

388.58ppm CO2, 1792.73ppb CH4, 95.70ppb CO, 324.36ppb N2O and

7.06ppt SF6; and NAT (since May-10 until Aug-11) – 389.13ppm CO2,

1778.85ppb CH4, 76.89ppb CO, 324.07ppb N2O and 7.07ppt SF6,

generally being between the two global stations. The results of GHG in

NAT have a homogeneous standard without seasonality. The results on

SAL show that air masses arriving from the NAO are directly linked to

increase concentrations, and lower concentrations are linked with the

conditions of wind speed and period of calm.

Were established two locations along the Brazilian northeast coast to do the

air samples collect, Natal, RN (NAT: 5.50ºS, 35.25ºW), and Salinópolis, PA (SAL:

0.60ºS, 47.36ºW). The values obtained were compared with two NOAA's global

stations, Ascension Island (ASC: 8ºS, 14ºW) in the South Atlantic Ocean (SAO)

and Barbados Island (RPB: 13ºN, 59ºW) in the North Atlantic Ocean (NAO). The

air sampling was performed on the surface, using glass flasks, being sampled in

pairs to obtain a mean concentration. Air samples were analyzed in the

Atmospheric Chemistry Laboratory of IPEN. It was determined the route travelled

by air masses trajectories in the five days preceding the day of sampling using

the HYSPLIT simulator[1], making it possible to determine the seasonality of the

origin of air masses for the latitudes studied.

I N T R O D U C T I O N

M E T H O D O L O G Y

R E S U LT S A N D D I S C U S S I O N C O N C L U S I O N S

[1]DRAXLER, R.R.; ROLPH, G.D., 2003. HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY, Disponível

em website: <http://www.arl.noaa.gov/ready/hysplit4.html>. NOAA Air Resources Laboratory, Silver Spring, MD.

R E F E R E N C E S A C K N O W L E D G E M E N T S

The trajectories of air masses in NAT have a homogenous pattern coming of

SAO latitude below ASC. Observing the results of GHG can be noted the

concordance with the measured values of this island, showing a homogeneity

concentrations along the year in SAO, without seasonality. The SAL air masses

trajectories results show that its coming mostly from SAO and a small part coming

from NAO and this latter coincides with the GHG higher concentrations period.

Can be observed a seasonally between January to April for both years. When the

air masses trajectory spend over the SAL city, the local influence have been

altering the concentration of GHG studied and the human activities during

summer also influence the concentrations of SAL.

From April to July occur a different phenomenon in SAL, where CO2

concentrations are presented below ASC, analyzing the conditions of wind

speed, it was found calm periods. Factors as high marine productivity and

calm would result in a greater CO2 absorption and consequently lower

concentrations in the air. This difference occurs in both years showing a

seasonality of this site. Notices that the N2O concentrations are above of

ASC and RPB most of the period studied. Reasons for this phenomenon

may be related to the shelf, estuaries and the fact the ocean is an

important source of this gas.

CH4 (ppb)

2010

SITE MEAN

SAL 1786.27

NAT* 1774.33

CO2 (ppm)

2010

SITE MEAN

SAL 387.81

NAT* 388.64

CO (ppb)

2010

SITE MEAN

SAL 97.46

NAT* 79.95

N2O (ppb)

2010

SITE MEAN

SAL 324.15

NAT* 323.88

SF6 (ppt)

2010

SITE MEAN

SAL 7.00

NAT* 6.98

Study sites along the Brazilian coast and the NOAA global stations.

Mean concentrations of GHG in SAL, NAT, ASC and RPB. * Mean in NAT since May-10 until Dec-10