Effects of the Tibetan Plateau on total column ozone distribution

Tellus B ◽  
2008 ◽  
Vol 60 (4) ◽  
pp. 622-635 ◽  
Author(s):  
Wenshou Tian ◽  
Martyn Chipperfield ◽  
Qian Huang
Tellus B ◽  
2008 ◽  
Vol 60 (4) ◽  
Author(s):  
Wenshou Tian ◽  
Martyn Chipperfield ◽  
Qian Huang

Tellus B ◽  
2014 ◽  
Vol 66 (1) ◽  
pp. 23415 ◽  
Author(s):  
Jiankai Zhang ◽  
Wenshou Tian ◽  
Fei Xie ◽  
Hongying Tian ◽  
Jiali Luo ◽  
...  

2019 ◽  
Author(s):  
Yajuan Li ◽  
Martyn P. Chipperfield ◽  
Wuhu Feng ◽  
Sandip S. Dhomse ◽  
Richard J. Pope ◽  
...  

2019 ◽  
Author(s):  
Yajuan Li ◽  
Martyn P. Chipperfield ◽  
Wuhu Feng ◽  
Sandip S. Dhomse ◽  
Richard J. Pope ◽  
...  

Abstract. We use the ozone dataset from the Copernicus Climate Change Service (C3S) during 1979–2017 to investigate the long-term variations of the total column ozone (TCO) and the relative total ozone low (TOL) over the Tibetan Plateau (TP) during different seasons. Based on various regression models, the wintertime TCO over the TP decreases overall during 1979–2017 with ongoing decreases since 1997. We perform multivariate regression analysis to quantify the influence of dynamical and chemical processes responsible for the long-term TCO variability over the TP. We use both piecewise linear trend (PWLT) and equivalent effective stratospheric chlorine loading (EESC)-based regression models that include explanatory variables such as the 11-year solar cycle, quasi-biennial oscillation (QBO) at 30 hPa and 10 hPa and the geopotential height (GH) at 150 hPa. The 150 hPa GH is found to be a major dynamical contributor to the total ozone variability (8 %) over the TP in wintertime. We also find strong correlation between TCO in DJF and the following JJA, indicating that negative/positive anomalies in the wintertime build up persist into summer. We also use the TOMCAT/SLIMCAT 3-D chemical transport model to investigate the contributions of different factors to the ozone variations over the TP. Using identical regression model on simulated TCO time series, we obtain consistent results with C3S-based data. We perform two sensitivity experiments with repeating dynamics of 2004 and 2008 to further study the role that the GH at 150 hPa plays in the ozone variations over the TP. The GH differences between the two years show an obvious, negative centre near 150 hPa over the TP in DJF. Composite analysis show that GH fluctuations associated with Inter Tropical Convergence Zone, ENSO events or Walker circulation play a key role in controlling TCO variability in the lower stratosphere.


2020 ◽  
Vol 20 (14) ◽  
pp. 8627-8639 ◽  
Author(s):  
Yajuan Li ◽  
Martyn P. Chipperfield ◽  
Wuhu Feng ◽  
Sandip S. Dhomse ◽  
Richard J. Pope ◽  
...  

Abstract. Various observation-based datasets have confirmed positive zonal mean column ozone trends at midlatitudes as a result of the successful implementation of the Montreal Protocol. However, there is still uncertainty about the longitudinal variation of these trends and the direction and magnitude of ozone changes at low latitudes. Here, we use the extended Copernicus Climate Change Service (C3S) dataset (1979–2017) to investigate the long-term variations in total column ozone (TCO) over the Tibetan Plateau (TP) for different seasons. We use piecewise linear trend (PWLT) and equivalent effective stratospheric chlorine loading (EESC)-based multivariate regression models with various proxies to attribute the influence of dynamical and chemical processes on the TCO variability. We also compare the seasonal behaviour of the relative total ozone low (TOL) over the TP with the zonal mean at the same latitude. Both regression models show that the TP column ozone trends change from negative trends from 1979 to 1996 to small positive trends from 1997 to 2017, although the later positive trend based on PWLT is not statistically significant. The wintertime positive trend starting from 1997 is larger than that in summer, but both seasonal TP recovery rates are smaller than the zonal means over the same latitude band. For TP column ozone, both regression models suggest that the geopotential height at 150 hPa (GH150) is a more suitable and realistic dynamical proxy compared to a surface temperature proxy used in some previous studies. Our analysis also shows that the wintertime GH150 plays an important role in determining summertime TCO over the TP through persistence of the ozone signal. For the zonal mean column ozone at this latitude, the quasi-biennial oscillation (QBO) is nonetheless the dominant dynamical proxy. We also use a 3-D chemical transport model to diagnose the contributions of different proxies for the TP region. The role of GH150 variability is illustrated by using two sensitivity experiments with repeating dynamics of 2004 and 2008. The simulated ozone profiles clearly show that wintertime TP ozone concentrations are largely controlled by tropics to midlatitude pathways, whereas in summer variations associated with tropical processes play an important role. These model results confirm that the long-term trends of TCO over the TP are dominated by different processes in winter and summer. The different TP recovery rates relative to the zonal means at the same latitude band are largely determined by wintertime dynamical processes.


2014 ◽  
Vol 14 (11) ◽  
pp. 5311-5325 ◽  
Author(s):  
J. Ma ◽  
W. L. Lin ◽  
X. D. Zheng ◽  
X. B. Xu ◽  
Z. Li ◽  
...  

Abstract. In situ measurements of ozone (O3), carbon monoxide (CO) and meteorological parameters were made from December 2007 to November 2009 at the Xianggelila Regional Atmosphere Background Station (28.006° N, 99.726° E; 3580 m a.s.l.), southwest China. It was found that both O3 and CO peaked in spring while the minima of O3 and CO occurred in summer and winter, respectively. A normalized indicator (marked as "Y") on the basis of the monthly normalized O3, CO and water vapor, is proposed to evaluate the occurrence of O3 downward transport from the upper, O3-rich atmosphere. This composite indicator has the advantage of being less influenced by the seasonal or occasional variations of individual factors. It is shown that the most frequent and effective transport occurred in winter (accounting for 39% of the cases on the basis of a threshold of the Y value larger than 4) and they can make a significant contribution to surface O3 at Xianggelila. A 9.6 ppb increase (21.0%) of surface ozone is estimated based on the impact of deep downward transport events in winter. A case of strong O3 downward transport event under the synoptic condition of a deep westerly trough is studied by the combination of the Y indicator, potential vorticity, total column ozone and trajectory analysis. Asian monsoon plays an important role in suppressing O3 accumulation in summer and fall. The seasonal variation of O3 downward transport, as suggested by the Y indicator at Xianggelila, is consistent with the seasonality of stratosphere-to-troposphere transport and the subtropical jet stream over the Tibetan Plateau.


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