El Niño-Southern Oscillation in Tropical Column Ozone and A 3.5-year signal in Mid-Latitude Column Ozone Jingqian Wang, 1* Steven Pawson, 2 Baijun Tian, 3 Run-Lie Shia, 4 Yuk L. Yung, 4 and Xun Jiang 1
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El Niño-Southern Oscillation in Tropical Column Ozone and A 3.5-year signal in Mid-Latitude Column Ozone
Jingqian Wang,1* Steven Pawson,2 Baijun Tian,3 Run-Lie Shia,4 Yuk L. Yung,4 and Xun Jiang1
1 Department of Earth and Atmospheric Sciences, University of Houston, TX 77204, USA. 2 Global Modeling and Assimilation Office, NASA GSFC, Code 610.1, Greenbelt, MD 20771, USA.
3 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA. 4 Division of Geological and Planetary Sciences, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
Regression Between O3 and Tropopause Pressure
Time Series of PC1
In this work, the impact of El Niño-Southern Oscillation (ENSO) on the tropical column ozone, tropical tropopause pressure, and the 3.5-year ozone signal in the mid-latitude column ozone are examined by Version 1 of the Goddard Earth Observation System Chemistry-Climate Model (GEOS CCM) [Pawson et al., 2008]. Observed monthly-mean sea surface temperature and sea ice between 1951 and 2004 were used as boundary conditions for the model. The ENSO signal is the dominant mode in the tropical column ozone variability in the GEOS CCM, capturing 65.8% of the total variance. The spatial pattern of this mode is similar to that in Total Ozone Mapping Spectrometer (TOMS) observations between Nov 1978 and Apr 1993. However, there are some discrepancies in ozone spatial pattern in the southern hemisphere between the GEOS CCM and TOMS. There is also a clear ENSO signal in the tropical tropopause pressure in the GEOS CCM, which may be the cause of the ENSO signal in the column ozone in the GEOS CCM. The regression coefficient between the model O3 and the model tropopause pressure is 0.78 DU/hPa, which is consistent with observations.
A 3.5-yr signal is found in the monthly mean ozonesonde data in the mid-latitude. The 3.5-yr signal is also found in the column ozone simulated by the GEOS CCM when similar analysis is applied. Using Empirical Mode Decompostion (EMD) analysis method, the 3.5-yr signal is very significant in both ozonesonde data and model data, which suggests that the model with realistic ENSO can reproduce the 3.5-yr signal. So it is likely that the 3.5-yr signal is from the ENSO signal.
Figure 4: (a) First mode of column O3 averaged in Niño-3.4 region (solid line) and first mode of tropopause pressure in Niño-3.4 region (dotted line). (b) Scatter plot of O3 against the tropopause pressure. Solid line is the linear fitting of the dots.
Power Spectrum of PC1
Data and Methods
I: Goddard Earth Observation System, Version 4 (GEOS-4) Chemistry-Climate Model
II: Ozonesonde Data (1951-2004)
III: Sea Surface Temperature: SST [Rayner et al., 2003]
I: Remove seasonal cycle and trend from data.
II: Apply Principal Component Analysis [Preisendorfer, 1988] to the deseasonalized and
III: Power Spectral Analysis will be applied to Principal Component (PC) timeseries.
IV: Independent Method, Empirical mode decomposition (EMD) [Huang et al., 1998],
will be applied to ozonesonde and model outputs
Figure 2: (a) Power spectrum of PC1 for the first mode of SST from GEOS-4 CCM. (b) Power spectrum of PC1 for the first mode of tropopause pressure from GEOS-4 CCM. (c) Power spectrum of PC1 for the first mode of column ozone from GEOS-4 CCM.
Figure 5: Power spectra of ozonesonde data (left) and GEOS-CCM result (right). Dash-dot lines and dashed lines correspond to 10% and 5% significance levels, respectively.
Spatial Pattern of Mode 1
Table 1: Variances, spectral peaks, and correlations (Lag = 0) for the first modes of the sea surface temperature, tropopause pressure, and column ozone. The numbers in parentheses denote significance levels.
Figure 3: (a) The spatial pattern of the first mode for SST in the tropics. (b) The spatial pattern of the first mode for tropopause pressure from GEOS-4 CCM in the tropics. (c) The spatial pattern of the first mode for column ozone from GEOS-4 CCM in the tropics.