Tropopause folds are one of the key mechanisms of stratosphere-troposphere exchange （STE） in extratropical regions, transporting ozone-rich stratospheric air into the middle and lower troposphere. Although there hav...Tropopause folds are one of the key mechanisms of stratosphere-troposphere exchange （STE） in extratropical regions, transporting ozone-rich stratospheric air into the middle and lower troposphere. Although there have been many studies of tropopause folds that have occurred over Europe and North America, a very limited amount of work has been carried out over northeastern Asia. Ozonesondes produced by the Institute of Atmospheric Physics were launched in Changchun （43.9°N, 125.2° E）, Northeast China, in June 2013, and observed an ozone-enriched layer with thickness of 3 km and an ozone peak of 180 ppbv at 6 km in the troposphere. The circulation field from the European Centre for Medium-Range Weather Forecasts Interim Reanalysis （ERA-Interim） dataset shows that this ozone peak was caused by a tropopause fold associated with a jet stream at the eastern flank of the East Asian trough. By analyzing the ozone data from the ozone monitoring instrument and Weather Research and Forecasting model with Chemistry （WRF-Chem） simulations, it was found that a high ozone concentration tongue originating from the lower stratosphere at high latitude （near central Siberia） intruded into the middle troposphere over Changchun between 5 and 8 km on 12 June 2013. The high-resolution WRF-Chem simulation was capable of describing events such as the tropopause fold that occurred on the cyclonic shear side of the jet stream. In addition, the TRAJ3D trajectory model was used to trace the origin of measured secondary ozone peaks in the middle troposphere back, for example, to stratospheric intrusion through the tropopause fold.展开更多
This paper investigates, the variability and correlation of surface ozone (Os) and carbon monoxide (CO) observed at Cape D'Aguilar in Hong Kong from 1 January 1994 to 31 December 1995. Statistical analysis shows t...This paper investigates, the variability and correlation of surface ozone (Os) and carbon monoxide (CO) observed at Cape D'Aguilar in Hong Kong from 1 January 1994 to 31 December 1995. Statistical analysis shows that the average O3 and CO mixing ratios during the two years are 32±17ppbv and 305±191 ppbv, respectively. The O3/CO ratio ranges from 0.05 to 0.6 ppbv/ppbv with its frequency peaking at 0.15. The raw dataset is divided into six groups using backward trajectory and cluster analyses. For data assigned to the same trajectory type, three groups are further sorted out based on CO and NOX mixing ratios. The correlation coefficients and slopes of O3/CO for the 18 groups are calculated using linear regression analysis. Finally, five kinds of air masses with different chemical features are identified: continental background (CB), marine background (MB), regional polluted continental (RPC), perturbed marine (P*M), and local polluted (LP) air masses. Further studies indicate that O3 and CO in the continental and marine background air masses (CB and MB) are positively correlated for the reason that they are well mixed over the long range transport before arriving at the site. The negative correlation between O3 and CO in air mass LP is believed to be associated with heavy anthropogenic influence, which results from the enhancement by local sources as indicated by high CO and NOx and depletion of O3 when mixed with fresh emissions. The positive correlation in the perturbed marine air mass P*M favors the low photochemical production of O3. The negative correlation found in the regional polluted continental air mass RPC is different from the observations at Oki Island in Japan due to the more complex O3 chemistry at Cape D'Aguilar.展开更多
We investigate the Madden-Julian Oscillation （MJO） signal in wintertime stratospheric ozone over the Tibetan Plateau and East Asia using the harmonized dataset of satellite ozone profiles. Two different MJO indices ...We investigate the Madden-Julian Oscillation （MJO） signal in wintertime stratospheric ozone over the Tibetan Plateau and East Asia using the harmonized dataset of satellite ozone profiles. Two different MJO indices -- the all-season Real-Time multivariate MJO index （RMM） and outgoing longwave radiation-based MJO index （OMI） -- are used to compare the MJO- related ozone anomalies. The results show that there are pronounced eastward-propagating MJO-related stratospheric ozone anomalies （mainly within 20-200 hPa） over the subtropics, The negative stratospheric ozone anomalies are over the Tibetan Plateau and East Asia in MJO phases 4-7, when MJO-related tropical deep convective anomalies move from the equatorial Indian Ocean towards the western Pacific Ocean. Compared with the results based on RMM, the MJO-related stratospheric column ozone anomalies based on OM1 are stronger and one phase ahead. Further analysis suggests that different sampling errors, observation principles and retrieval algorithms may be responsible for the discrepancies among different satellite measurements. The MJO-related stratospheric ozone anomalies can be attributed to the MJO-related circulation anomalies, i.e., the uplifted tropopanse and the northward shifted westerly jet in the upper troposphere. Compared to the result based on RMM, the upper tropospheric westerly jet may play a less important role in generating the stratospheric column ozone anomalies based on OMI. Our study indicates that the circulation-based MJO index （RMM） can better characterize the MJO- related anomalies in tropopause pressure and thus the MJO influence on atmospheric trace gases in the upper troposphere and lower stratosphere, especially over subtropical East Asia.展开更多
基金supported by the National Basic Research Program of China under Grant No.2010CB428602the National Natural Science Foundation of China (Grant No. 41175040)
文摘Tropopause folds are one of the key mechanisms of stratosphere-troposphere exchange （STE） in extratropical regions, transporting ozone-rich stratospheric air into the middle and lower troposphere. Although there have been many studies of tropopause folds that have occurred over Europe and North America, a very limited amount of work has been carried out over northeastern Asia. Ozonesondes produced by the Institute of Atmospheric Physics were launched in Changchun （43.9°N, 125.2° E）, Northeast China, in June 2013, and observed an ozone-enriched layer with thickness of 3 km and an ozone peak of 180 ppbv at 6 km in the troposphere. The circulation field from the European Centre for Medium-Range Weather Forecasts Interim Reanalysis （ERA-Interim） dataset shows that this ozone peak was caused by a tropopause fold associated with a jet stream at the eastern flank of the East Asian trough. By analyzing the ozone data from the ozone monitoring instrument and Weather Research and Forecasting model with Chemistry （WRF-Chem） simulations, it was found that a high ozone concentration tongue originating from the lower stratosphere at high latitude （near central Siberia） intruded into the middle troposphere over Changchun between 5 and 8 km on 12 June 2013. The high-resolution WRF-Chem simulation was capable of describing events such as the tropopause fold that occurred on the cyclonic shear side of the jet stream. In addition, the TRAJ3D trajectory model was used to trace the origin of measured secondary ozone peaks in the middle troposphere back, for example, to stratospheric intrusion through the tropopause fold.
文摘This paper investigates, the variability and correlation of surface ozone (Os) and carbon monoxide (CO) observed at Cape D'Aguilar in Hong Kong from 1 January 1994 to 31 December 1995. Statistical analysis shows that the average O3 and CO mixing ratios during the two years are 32±17ppbv and 305±191 ppbv, respectively. The O3/CO ratio ranges from 0.05 to 0.6 ppbv/ppbv with its frequency peaking at 0.15. The raw dataset is divided into six groups using backward trajectory and cluster analyses. For data assigned to the same trajectory type, three groups are further sorted out based on CO and NOX mixing ratios. The correlation coefficients and slopes of O3/CO for the 18 groups are calculated using linear regression analysis. Finally, five kinds of air masses with different chemical features are identified: continental background (CB), marine background (MB), regional polluted continental (RPC), perturbed marine (P*M), and local polluted (LP) air masses. Further studies indicate that O3 and CO in the continental and marine background air masses (CB and MB) are positively correlated for the reason that they are well mixed over the long range transport before arriving at the site. The negative correlation between O3 and CO in air mass LP is believed to be associated with heavy anthropogenic influence, which results from the enhancement by local sources as indicated by high CO and NOx and depletion of O3 when mixed with fresh emissions. The positive correlation in the perturbed marine air mass P*M favors the low photochemical production of O3. The negative correlation found in the regional polluted continental air mass RPC is different from the observations at Oki Island in Japan due to the more complex O3 chemistry at Cape D'Aguilar.
基金funded by the National Natural Science Foundation of China(Grant No.41105025)the Dragon 3 Programme(ID:10577)the High Resolution Earth Observation Funds for Young Scientists(Grant No.GFZX04060103)
文摘We investigate the Madden-Julian Oscillation （MJO） signal in wintertime stratospheric ozone over the Tibetan Plateau and East Asia using the harmonized dataset of satellite ozone profiles. Two different MJO indices -- the all-season Real-Time multivariate MJO index （RMM） and outgoing longwave radiation-based MJO index （OMI） -- are used to compare the MJO- related ozone anomalies. The results show that there are pronounced eastward-propagating MJO-related stratospheric ozone anomalies （mainly within 20-200 hPa） over the subtropics, The negative stratospheric ozone anomalies are over the Tibetan Plateau and East Asia in MJO phases 4-7, when MJO-related tropical deep convective anomalies move from the equatorial Indian Ocean towards the western Pacific Ocean. Compared with the results based on RMM, the MJO-related stratospheric column ozone anomalies based on OM1 are stronger and one phase ahead. Further analysis suggests that different sampling errors, observation principles and retrieval algorithms may be responsible for the discrepancies among different satellite measurements. The MJO-related stratospheric ozone anomalies can be attributed to the MJO-related circulation anomalies, i.e., the uplifted tropopanse and the northward shifted westerly jet in the upper troposphere. Compared to the result based on RMM, the upper tropospheric westerly jet may play a less important role in generating the stratospheric column ozone anomalies based on OMI. Our study indicates that the circulation-based MJO index （RMM） can better characterize the MJO- related anomalies in tropopause pressure and thus the MJO influence on atmospheric trace gases in the upper troposphere and lower stratosphere, especially over subtropical East Asia.
