Satellite observations and model simulations of tropospheric NO2 columns over south-eastern Europe
Other literature type
Koukouli, M. E.
Balis, D. S.
der A, R.
Boersma, F. K.
(issn: 1680-7324, eissn: 1680-7324)
Satellite observations of nitrogen dioxide (NO<sub>2</sub>) tropospheric columns
over south-eastern Europe are analyzed to study the characteristics of the
spatial and temporal variability of pollution in the area. The interannual
variability of the tropospheric NO<sub>2</sub> columns is presented over urban,
rural and industrial locations based on measurements from four satellite
instruments, GOME/ERS-2, SCIAMACHY/Envisat, OMI/Aura and GOME-2/MetOp
spanning a period of over twelve years. The consistency between the
different datasets over the area is investigated. Two operational algorithms
for the retrieval of tropospheric NO<sub>2</sub> are considered, the one developed
jointly by the Royal Netherlands Meteorological Institute and Belgian
Institute for Space Astronomy and the one developed by the University of
Bremen. The tropospheric NO<sub>2</sub> columns for the area under study have been
simulated for the period 1996–2001 with the Comprehensive Air Quality Model
(CAMx) and are compared with GOME measurements. Over urban and industrial
locations the mean tropospheric NO<sub>2</sub> columns range between 3 and
7.0×10<sup>15</sup> molecules/cm<sup>2</sup>, showing a seasonal variability with a peak to
peak amplitude of about 6.0×10<sup>15</sup> molecules/cm<sup>2</sup>, while the
background values over rural sites are close to 1.1×10<sup>15</sup> molecules/cm<sup>2</sup>.
Differences in the overpass time and spatial
resolution of the different satellites, as well as differences in the
algorithms, introduce significant differences in the estimated columns
however the correlation between the different estimates is higher than 0.8.
It is found that the model simulations reveal similar spatial patterns as
the GOME observations, a result which is consistent with both algorithms.
Although the model simulations show a mean bias of −0.1×10<sup>15</sup> molecules/cm<sup>2</sup>
under clean conditions, the modeled temporal
correlation of 0.5 is poor in absence of biogenic and biomass burning