Student : Shen-Feng Chang Advisor : Yi-Chyun Hsu Atmospheric Environment 43 (2009) 584–593 journal homepage: Aircraft measurements of O 3, NO x, CO, VOCs, and SO 2 in the Yangtze River Delta region

 Introduction  Description of the measurements  Analysis of the result

 The Yangtze River Delta (YRD) region located in east China (with longitude from 120°E to 121°E, and latitude from 30.5°N to 31.5°N) is highly urbanized with a cluster of large cities (including Shanghai, Hangzhou, Shuzhou, Wuxi, etc.).  Among these large cities, Shanghai has the highest population in China (about 20 millions).  During the past 20 years, this region is undergoing a rapid increase in economical development.  Introduction (1/3)

 The GDP has increased by 500% from 1996 to 2006, accounting for more than 5% of the total GDP in China.  The rapid urbanization causes wide-ranging potential consequences for weather and climate related to urban environments, such as air pollutions.  Like other large cities in east China, Shanghai is suffering severe air pollution problems, such as high particular matter (PM) concentrations and poor visibility.  Introduction (2/3)

 Introduction (3/3)  As industrial activities and the number of automobiles increase together with the changes in natural activities (such as vegetation and forest), emission of VOCs and NO x will significantly increase in the YRD region.  Both VOCs and NOx play critical roles during O 3 formation in the troposphere.  Several studies regarding the air quality in the YRD region have been conducted.

 Description of the measurements (1/2)  Fig. 1 displays the horizontal routes for several representative flights.  It shows that the flight routes are located in west side of the megacity (Shanghai) with several large cities, such as Suzhou, Wuxi and Jiading.  In addition, there are several large power plants in this region. For example, the Changshou power plant generates 1200MW per year.

 Description of the measurements (2/2)  There are totally five flights between September/30 and October/11 (flight-1 on September/30, flight-2 on October/2, flight-3 on October/5, flight-4 on October/9, and flight-5 on October/11), which are analyzed in this study.  There are also several inter-state high ways, and high density of small towns and villages.  As a result, the local emissions of air pollutants from automobiles, and area and point sources are intensive.

 Analysis of the result (1/2)  Both the O 3 mean values are generally lower than the US national standard values (84 ppbv), suggesting that the O 3 values are modest in the YRD region.  The NO x concentrations have large variability, ranging from 3 to 40 ppbv.  The highest concentrations of NO x are observed normally in the NCITY case, ranging from 10 to 40 ppbv.

 Analysis of the result (2/2)  The SO 2 concentrations also have a large variability, ranging from 1 to 35 ppbv.  The highest concentrations of SO 2 are measured in the NCITY case, ranging from 7 to 35 ppbv.  The CO concentrations are relatively high, and have smaller variability compared to NO x and SO 2, ranging from 3 to 7 ppmv.

The results are summarized in the follows: (1) The measured O 3 concentrations range from 20 to 60 ppbv. These values are normally below the US national standard (84 ppbv), suggesting that at the present, the O 3 pollutions are modest in this region. The NO x concentrations have a large variability, ranging from 3 to 40 ppbv. The SO 2 concentrations have very large variability, ranging from 1 to 35 ppbv.

The CO concentrations are relatively high, and have less variability, ranging from 3 to 7 ppmv. The concentrations of VOCs are relatively small, with the total VOC concentration of 6 ppbv. Among the total VOCs, alkanes have highest values (2.8 ppbv). (2) The relatively small VOC concentrations and large NO x concentrations indicate that the O 3 chemical formation is under “VOC-limited” regime in the YRD region.

The measured O 3 and NO x concentrations are strongly anti-correlated, suggesting that enhancements in NO x concentrations lead to decrease in O 3 concentrations. (3) The O 3 concentrations are more sensitive to NO x concentrations in the rural PBL region than in the city region. This result suggests that changes in NO x emissions could have strong effects on O 3 concentrations in rural areas of the YRD region.

(4) The O 3 -isopleth diagram study shows that the O 3 concentrations could increase rapidly with increase in VOC concentrations in the YRD region. For example, if the VOC concentrations increase to 75 ppbC in the future, O 3 concentrations could exceed to 84 ppbv, which is normally considered as the national standard for human’s health.

Thank you for your attention!