**Acknowledgements**

as obvious as that of PM10. For evaluating the influence of wheat straw burning on local air pollution, the values of NO2 and SO2 on June 11, before wheat straw burning, were taken as the background values. The NO2 values obtained after wheat straw burning on June 13, and again the SO2values obtained on June 14, were recorded and evaluated. From these evaluation results, it's concluded that from the end of May to the middle of June, concentration of gaseous pollutants (NO2 and SO2) and particulate matter increased obviously due to straw burning in

CCR is an important industrial site in the mid- west region of China. Historical review of satellite data shows that the cities with relatively serious air pollution are confined mainly to the north because of their geographic location, weather conditions and industrial activity. Besides, the "accumulation zone" of pollutants exists in the region east of Tai-hang Mountains. Analysis of the data obtained from stereoscopic monitoring of the selected sites shows that the prevalence of pollution at the three sites, AY, JZ and SMX, was almost simultaneous. However, AY was characterized by local pollution (local source) and JZ by near-ground pollution, where the pollution concentration was also higher due to higher emission of industrial gases. Though local pollution was milder at SMX, it still can be easily aggravated by northwest sand dust transportation. Through statistical analysis of satellite and ground monitoring data, pollution was more serious during the 1st and 4th quarters (winter and spring), followed by the 2nd quarter and the 3rd quarter. During the heating period, the air pollution intensified obviously, because the urban energy consumption structure was still coal-oriented. During late May to mid-June, straw burning in the south CCR and surrounding provinces, such as Anhui and

Jiangsu, contributed to the increase of aerosol, NO2 and SO2, in some cities of CCR.

As for the reasons for the complex process of haze formation, it was found that local pollution (local sources) was the main cause, besides the effect of superposition of pollution transpor‐ tation in some time frames. Near-ground pollution at the three sites was caused mainly by local pollution (industrial emission, motor vehicle exhaust, coal combustion, etc.) and pollu‐ tion transportation of some northern cities in the southeast direction. AY was more affected by local transportation and emissions from some industrial parks, and JZ by near-ground local pollution. Moreover, pollution concentration was higher at JZ than that at AY because of more industrial emissions. Local pollution at SMX was comparatively less obvious, but was lasting longer due to the unfavorable diffusion condition. In CCR, formation of ground weather situations of uniform-pressure field and North China low pressure, which are bad for pollutant diffusion, is easy. Such weather has lower ground pressure field, and smaller speeds of ground and low-altitude winds, which are sometimes calm. It is often accompanied with stronger radiation inversion or low-altitude temperature inversion that is difficult to eliminate. The structure of lower atmosphere layer is stable and might contribute to higher pollution.

So far many efforts were made from ground based and space borne observations to study aerosol distribution and properties, along with model simulations, but such integrated studies

CCR and surrounding cities.

**4. Conclusions**

270 Current Air Quality Issues

This work was supported by the Funding from Henan Program (Researches on Atmospheric Haze pollution in Henan Province), Major State Basic Research Development Program of China (2014CB447900) and NSFC (41305126). The authors are also thankful to the NOAA Air Resources Laboratory (ARL) for providing the HYSPLIT transport and dispersion model used in this research.
