Singular spectrum analysis, harmonic regression and El-Nino effect on total ozone (1979–1993) over India and surrounding regions

Journal of earth system science

Chandramadhab Pal^1¹ 

[1] Department of Physics, Ramakrishna Mission Vidyamandira, Belurmath, Howrah 711 202, India^1

关键词: Total ozone;    singular spectrum analysis;    spatial interpolation;    multivariate ENSO Index;    Dipole Mode Index;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

The Total Ozone Mapping Spectrometer (TOMS) is a satellite instrument that records Total Column Ozone (TCO) concentration (in DB) of the atmosphere in the form of different overpass files. We have selected 23 sites over India (15), Pakistan (4), Bangladesh (1) and adjoining China (3) to investigate theTCO scenario over this region. About 114,000 historical records (1979M1–1992M12) from 23 overpass files were processed to generate 23 monthly mean time series (TS) of TCO. Statistical analysis followedby singular spectrum analysis (SSA), harmonic regression (HR) and spatial interpolation have been used to accomplish the investigation. Four dominant signals; quasi-biennial signal (QBI, T = 30.12 months), quasi-annual signal (QAN, T = 19.69 months), annual signal (ANN, T = 12 months) and semi-annual signal (SAN, T = 6 months) were discerned to explain the variability. Direct latitudinal effect on theTCO distribution was observed. The variance was limited between 80.53 and 90.13%; ANN contributes 65.93–93.22% followed by SAN 0.58–5.69%, QAN 0.33–5.48%, and QBI 0.06–5.94%. Peak values of the oscillations are estimated from phasor diagrams: QBI, March to May in the mid-latitude; QAN, April,and May; ANN, February to April; SAN, March to May. Incisive pictures of the average distribution and variability of four sinusoids were investigated from contour plots. Two ozone valley were discerned from Spatial interpolation; one over Deccan Plateau in low and other over Tibetan Plateau in high latitude.179 outliers from 23 × 168 observations have been identified after harmonic regression. The appearance of the outliers is highly consistent with extreme phases of multivariate ENSO Index and Dipole Mode Index.

【 授权许可】

CC BY