A Study of Spatial-Temporal Evolvement of the Global Cross-Tropopause Ozone Mass Flux

This study investigates the Stratosphere-Troposphere Exchange (STE) of water vapor, emphasizes its inter-decadal variations over Asia in boreal summer, and discusses the influences of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific (WNP) on them by using theWei method with reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF) for the years of 1958-2001. The climatology shows that the upward transport of water vapor across the tropopause in boreal summer is the most robust over the joining area of the South Asian Peninsula and Indian-Pacific Oceans (defined as AIPO). The upward transport over there can persistently convey the abundant water vapor into the stratosphere and then influence the distribution and variation of the stratospheric water vapor. The analysis shows that inter-decadal variations of the water vapor exchange over the AIPO are significant, and its abrupt change occurred in the mid-1970s and the early 1990s. In these three periods, as important channels of the water vapor exchange, the effect of Bay of Bengal-East Asia as well as South China Sea was gradually weakening, while the role of the WNP becomes more and more important. Further studies show that atmospheric heat sources over the Tibetan Plateau and the WNP are two main factors in determining the inter-decadal variations of water vapor exchange. The thermal influences over the Tibetan Plateau and the WNP have been greatly adjusted over the pass 44 years. Their synthesis influences the inter-decadal variations of the water vapor exchange by changing the Asian summer monsoon, but their roles vary with time and regions. Especially after 1992, the influence of heat source over the Tibetan Plateau remarkably weakens, while the heat source over the WNP dominates the across-tropopause water vapor exchange. Results have important implications for understanding the transport of other components in the atmosphere and estimating the impact of human activities (emission) on global climate. Tibetan Plateau, tropical western North Pacific, atmospheric heat source, STE, inter-decadal variationsWater vapor in the Upper Troposphere and Lower Stratosphere (UTLS) is a key greenhouse gas which exerts a major influence on the energy balance of the earth-atmosphere system. Water vapor is also important for atmospheric chemistry as the primary source of the hydroxyl radical, which changes ozone concentration and eliminates the contamination in the atmosphere by participating in the photochemical processes in UTLS. The water vapor balance in the UTLS is dominated by

Sci. China Ser. D-Earth Sci.

Section: Methodsmentioning

confidence: 99%

Influence of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific on the inter-decadal variations of the stratosphere-troposphere exchange of water vapor

Zhan

2008

“…As the effective STE processes mostly occur in UTLS within a certain thickness [8] , taking the transitional nature of tropopause into account, we select a 6 km thick layer (3 km above and below tropopause) TPP±3 (TPP is tropopause) as UTLS airspace. Therefore, the average ozone mixing ratio in TPP±3 can be expressed as q TPP±3,O3 = pTPP+3 pTPP−3 q(p)dp pTPP+3 pTPP−3 dp ,…”

Section: Calculation Of Ozone Contentmentioning

confidence: 99%

A Study of Ozone Amount in the Transition Layer Between Troposphere and Stratosphere and Its Heating Rate

Yuan

Chinese J of Geophysics

et al. 2008

Self Cite

Using the 44‐yr (1958~2001) dataset provided by ECMWF and the parameterization method, the spatial‐temporal distribution of ozone amount in the 6‐km layer near the tropopause and the heating rate are calculated. The results show that: (1) the spatial gradient of ozone distribution is from equatorial to polar regions, while the spatial gradient of the heating rate distribution is from the high‐latitude and low‐latitude to the subtropics. It is likely that such meridional gradient is an important factor which drives the tropopause structure variations. The seasonal variation of the spatial distributions of ozone amount and heating rate is obvious, while they are not fully consistent with each other. The spatial structure in January and April is reverse with that in July and October and abrupt change exists along with season varying. The seasonal change is relatively stable in East Asia and the Qinghai‐Tibet Plateau. (2) The heating rate and ozone amount shows positive correlation in the areas controlled by tropopause in tropics, and the relationship varies with seasons in the areas controlled by the polar tropopause. Also this relationship has something to do with the declination; there exists phase of seasonal variation and the variability among the different latitudes, while it is more consistent in Southern Hemisphere, the largest anomaly is ±2 × 10−4 K·d−1. And it is more complex in Northern Hemisphere, the largest positive anomaly is ±4 × 10−4 K·d−1. The seasonal phases are generally reverse in two Hemispheres. (3) The seasonal variation phase of ozone amount anomaly exceeds that of heating rate anomaly by 2~3 months in the period of seasonal adjustment, except in the equatorial areas; The largest anomaly is greater than 0.4 DU in August in Antarctic, and smaller than –0.2 DU in March and April; and it is ±0.2 DU in Arctic. (4) The interannual and interdecadal evolution of ozone amount and heating rate are correspondent, both show multi‐scale structure characteristics. The differences of spatial‐temporal evolutions between the two Hemisphere and equatorial areas are obvious. The amplitude of heating rate in the areas between 30°S~30°N is rather dramatic, and the largest anomaly is ±2.5×10−4 K·d−1, the amplitude in high‐ latitude and pole in two hemisphere is different in different periods; while the amplitude of ozone amount shows reverse characteristics. The largest anomaly is greater than 0.25 DU or smaller than –0.35 DU in Arctic areas. (5) There are opposite anomaly structures in two Hemispheres before 70's and mid‐70's in 20th century, while the most remarkable period of the minus anomaly is in 90's.

“…Thus, it can change the thermal and dynamic structure of both troposphere and stratosphere, as well as the trace gases spatial-temporal distribution in the atmosphere. And then it imposes effects on global climate change (Wang et al, 2006;Roscoe, 2006). So understanding the spatial-temporal distribution characters of BD circulation is quite important to further studying the interaction and mass (especially trace gases such as vapor, aerosol, ozone) exchange of troposphere-stratosphere, and also has important scientific meaning to the prediction of global climate change.…”

Section: Introductionmentioning

confidence: 99%

The Distribution Characters of the Stratospheric Brewer‐Dobson Circulation Inferred from Era‐Interim

Fu²,

Chinese J of Geophysics

et al. 2015

The spatial‐temporal distribution characters of trace gases in the stratosphere and troposphere are affected by the Brewer‐Dobson (BD) circulation. Understanding the distribution characters of the BD circulation is very important for further studying the influence of stratosphere and troposphere exchange and forecasting the global climate change. The BD circulation is described as the Lagrangian‐mean circulation, which is difficult to diagnose directly from meteorological observations. The methods of the transformed Eulerian‐mean (TEM) equations and integrating residual meridional velocity in the vertical were used to analyze the spatial‐temporal distribution characters of the BD circulation based on the ERA‐Interim reanalysis data at 12:00 UTC for 1979–2011. We further compared the distribution characters of BD circulation with the result calculated by the method of DC (Downward Control) principle and studied the relationship between the stratospheric zonal mean temperature and BD circulation. The BD circulation was calculated using ERA‐Interim reanalysis data for 1979–2011 by integrating residual meridional velocity in the vertical direction. The results show that the ascending centers of BD circulation varied with seasons. It ascended at 30°S in the stratosphere from December to February (DJF), while from June to August (JJA) it ascended between 25°N and 30°N. The circulation pattern in the winter hemisphere was stronger than the summer hemisphere. In March to May (MAM) and September to November (SON), the ascending centers were between equator to 5°N, and circulation were relatively symmetric between the two hemispheres. The maximum mass flux in the tropical and extratropical northern hemisphere appeared during DJF, and the minimum appeared during JJA. The mass flux in the extratropical southern hemisphere was just the opposite. Mass flux across the 100 hPa and 50 hPa pressure surface in the tropical and extratropical areas tended to decrease, and also varied obviously with the changing of season. The long‐term trend of stratospheric zonal mean temperature was consistent with the long‐term weakening trend of BD circulation, which indicates that the global BD circulation has been weakened. Meanwhile, the zonal mean temperature at different altitudes and latitudes varied with seasons. From the perspective of the global mass transportation, the stratospheric BD circulation has been weakened in the past 33 years, especially in the middle and lower stratosphere, which was consistent with the long‐term trend of temperature. This weakened trend was consistent with the observations of stratospheric air and other model results. But the method of DC principle, GCMs model and other studies show that the stratospheric BD circulation has been enhanced in the past years. Using different methods and data would make the trend estimation of BD circulation unreliable. Therefore, further research is required to improve this estimation.