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Nitrogen Dioxide (NO2): Europe air pollution

19 April 2015   //   by admin   //   Analysis  //  Comments (0)

Nitrogen Dioxide — is one of the most common atmospheric pollutants. Stimulates acid rain, affects the respiratory tract and lungs, causes changes in the composition of blood, in particular, reduces the content of hemoglobin in the blood.

Climate Wikience makes possible to quickly build air pollution risk maps using satellite data with high resolution. High resolution maps of air pollution risks allow answering many important questions in the domain of ecologic safety. For example, what countries have the highest level of air pollution and what is the relative level of air pollution between different regions inside a country.


Air pollution risk map by Nitrogen Dioxide (NO2) with spatial resolution
~27,5 km × 18 km (0,25° × 0,25°). Aura OMI satellite data 01.10.2004—31.12.2012.

Open NO2 air pollution risk map in Google Earth

The map color scheme is selected to be good for grey-scale printing. If you would like to print the information from this post, please refer to a publication.


The air pollution risk is defined as the probability of observing a pollutant concentration in a given interval over the territory under investigation. The risk is calculated for each grid cell. This risk calculation technique is simple yet delivers extensive understanding of typical air pollution character.

The risk of pollution for a grid cell equals to R(a, b) = S(a, b)/T, where S(a, b) is the number of days with nitrogen dioxide concentration in [a..b] interval (Dobson Units), and T is the number of days for which nitrogen dioxide measurements are not missing due to clouds or other reasons. Both S(a, b) and T are calculated for each grid cell.

This method, unlike previously proposed air pollution assessment techniques, takes into considerartion the whole available time interval, is resilient to outliers and tailored to building maps using Earth remote sensing data.

Pollution categories for NO2 are experimentally and subjectively defined as: 0.0..0.2 DU – low, 0.2..0.4 DU – moderate (open in Google Earth), 0.4..0.6 DU – high (open in Google Earth), 0.6..0.8 DU – very high, over 0.8 – disastrous.

Category intervals were selected to account for as many as possible NO2 pollution features (visually) and keep the number of categories acceptable.

To build the risk map, satellite air pollution data were used (Aura satellite, OMI instrument) during 01.10.2004—31.12.2012. Data are available daily and globally.


Rodriges Zalipynis R.A., Ecologic assessment of air pollution by nitrogen dioxide over the territory of Europe using Earth remote sensing data, Journal of Informatics, Cybernetics and Computing Machinery, № 1(19), 2014. – 162 pp. – P. 126 – 130.
PDF ~477 KB
Rodriges Zalipynis R.A., The place of Ukraine in Europe according to the level of air pollution using Earth remote sensing data, Proceedings of IV All-Ukrainian Congress of Ecologists with International Participation, Vinnytsia, Ukraine, 25 – 27 September, 2013. – 552 pp. – P. 130 – 132.
PDF ~600 KB
Rodriges Zalipynis R.A., Risks of air pollution by aerosols over the territory of Europe, Materialy IX Mezinarodni Vedecko – Prakticka Konference “Veda a technologie: krok do budoucnosti”, Prague, Czech Republic, 27 April – 05 March, 2013. – P. 35 – 42.

Isolines for satellite data

16 January 2015   //   by admin   //   Data, News  //  Comments (0)
Now Climate Wikience displays isolines for satellite data. Until now, Climate Wikience was able to display isolines only for data without missing values like climate reanalysis. However, satellite measurements often have areas without data due to clouds or other reasons. Improved algorithm of Climate Wikience now draws isolines for data with missing values.

Below are examples of visualizing isolines for satellite data.
Click an image for its bigger version.

Eastward wind speed for 10 meters above sea surface (u10m) on the 28th of August, 2005. Blended data product from several satellites including QuikSCAT, SSMIs, TMI and AMSR-E.

NASA MERRA Leaf Are Index (LAI) on the 28th of August, 2010.
Zoom at North America, Eurasia, and South America.
MERRA_LAI_LeafAreIndex_28Aug2010_ZoomNorthAmerica MERRA_LAI_LeafAreIndex_28Aug2010_ZoomEuropeAsia

You can label any isoline at its arbitrary point. Simply enable “Click for value” option at the “Properties tab”. A label with isoline value will appear at the point where you clicked on the isoline. Click on the isoline again to hide the label.
Zoom over South America with several labeled isolines and increased width of isolines (compare “Properties tab” of this image and the one below).
The same area without isolines labelling.

Aura OMI Nitrogen Dioxide (NO2) tropospheric concentration on the 1st of October, 2004.
Zoom over Los Angeles.

Terra MODIS Aerosol Optical Thickess (AOT) on the 1st of August, 2005.
Zoom over Africa

Terra MODIS Cloud Top Temperature on the 25th of August, 2005.
The 25th of August (2005) is the date for peak strength of hurricane Katrina.
The same areas without tropical cyclone tracks and without surface.
Modis_CLOUDTopTemperature_28Aug2005_withsurface   Modis_CLOUDTopTemperature_28Aug2005

Climate Wikience is able to interactively visualize tropical cyclones. Find out more at Tropical cyclones page.

NASA MERRA Greeness Vegetation Fraction on the 28th of August, 2010.
Zoom over North America and South America.


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