presented by Ulrich Schumann,
Deutsches Zentrum für Luft- und Raumfahrt (DLR)
Institute of Atmospheric Physics, Oberpfaffenhofen, Germany
The contributions of tropical continental deep convection to lightning-produced
nitrogen oxides (NOx) and to other trace gases (including water
vapor) and particles (ice crystal and aerosols) is being investigated
within the EU project TROCCINOX (Tropical
Convection, Cirrus, and Nitrogen Oxides Experiment).
The project is being performed in 2002-2005 in cooperation with
Brazilian partners. A first field experiment has been performed
in Brazil with the DLR Falcon in February and March 2004, a second
experiment is now being prepared to be performed between mid-January
and end of February 2005 including measurements with the Falcon
and the high-flying (up to 21 km altitude) Russian Geophysica aircraft.
The results from the first field experiment allow to constrain
the possible range of the global source rate of lightning induced
NOx. Measurements have been performed with the DLR Falcon on the
transfer flights between Oberpfaffenhofen (Germany) and Gaviao
Peixoto (S. P., Brazil) and during 14 local flights over Southern
Brazil. The aircraft was instrumented with in-situ sensors for
NO, NOy, O3, CO, H2O, T, NO2 photolysis rate, and various aerosols.
A differential absorption Lidar measures aerosol properties and
H2O profiles above or below the aircraft. Lightning induced NOx
has been measured in or near tropical and subtropical thunderstorms
at altitudes up to 12.5 km. In anvil outflow of thunderstorms,
spiky NO structures (maximum 65 nmol/mol) above background were
observed. Some of the spikes were notably wide (order several 10
km) indicating outflow from a thunderstorm anvil, others were narrow
(order 200 m) clearly originating from fresh lightning events.
Model studies and analysis of the NOx outflow from individual thunderstorm
cases indicate global lightning-NOx production rates between 2
and 9 Tg(N) yr-1.
Finally an outlook for using the new High Altitude and Long Range
Research Aircraft HALO (which is similar to HIAPER) will be presented.
Seminar is from 3:00 pm at FL1 Atrium on Thursday, December
16, 2004.
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