ACPD

Atmospheric Chemistry and Physics Discussions

ACPD

Atmos. Chem. Phys. Discuss.

1680-7375

Göttingen, Germany

10.5194/acpd-4-2263-2004

Sudden increases in the NO2 column caused by thunderstorms: a case study in the northern subtropical region

Gil

¹ Yela

¹ Cuevas

² Carreño

Area de Investigación e Instrumentación Atmosférica, INTA, Torrejón de Ardóz, 28850, Spain

Observatorio Atmosférico de Izaña, INM. La Marina 20, 38071 Sta. Cruz de Tenerife, Spain

04 05 2004

4 3 2263 2281

2004

This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/

This article is available from https://acp.copernicus.org/preprints/4/2263/2004/acpd-4-2263-2004.html

The full text article is available as a PDF file from https://acp.copernicus.org/preprints/4/2263/2004/acpd-4-2263-2004.pdf

A long-term program for NO2 column measurements started in 1993 at the subtropical Izaña Observatory (28° N, 16° W). Seasonal evolution shows a small day-to-day variability as compared with higher latitudes. Sharp increases in the column appear occasionally superimposed on the annual cycle. The origin of these spikes is explored by considering the possibility of tropospheric transport from polluted areas, stratospheric intrusions, meridional transport in the stratosphere and production by lightning, in a case study. From radiative transfer calculations and meteorological information available, it is shown that the NO2 increase takes place in the upper troposphere with values of 300–400 pptv. Back-trajectories reveal that, for the case studied, the air masses came from an area of thunderstorms located upwind. After the analysis of the various possibilities, the NO2 increase by lightning production appears to be the most feasible cause. Annual distribution of spikes displays a maximum in late winter and spring during the shift from midlatitude winter tropopause to summer tropopause.