Abstract
The Madden-Julian Oscillation (MJO) is the leading mode of intra-seasonal variability in the tropical troposphere, characterized by an eastward moving ‘pulse’ of cloud and rainfall near the equator. In this study, total precipitable water (TPW) and total column ozone (TCO) datasets from ECMWF ERA-Interim reanalysis were used to analyse the impact of the MJO on the distribution of water vapor and column ozone in the tropics from 1979 to 2013. The results show that seasonal variations of TPW modulated by the MJO are maximized in the tropics of about 10°S-10°N during boreal winter, while the variation in TCO is maximized in the mid-latitudes of about 30°S - 40°N in the same season. The composite analysis shows that MJO modulates TPW and TCO anomalies eastward across the globe. The underlying mechanism of the MJO’s impact on TPW is mainly associated with variation of tropical convection modulated by the MJO, while the underlying mechanism of the MJO’s impact on TCO is mainly associated with an intra-seasonal variability of tropopause height modulated by the MJO activity. This knowledge helps to improve the prediction skill of the intra-seasonal variation of water vapor and column ozone in the tropics during boreal winter.
Highlights
Tropical atmospheric circulations are controlled by the large-scale convective system varying in space and time, which includes the equatorial planetary waves [1][2][3], intra-seasonal oscillation (MJO) [4], inter-annual oscillation ENSO [5], and decadal to multidecadal oscillation
During the boreal summer, the Madden-Julian Oscillation (MJO) signal in outgoing longwave radiation (OLR) is strongly observed from the northern Indian Ocean to the western Pacific Ocean, while during boreal winter the higher variance of OLR is dominant in the Southern Hemisphere and covering wide area, from the Indian Ocean (50°E) to the eastern Pacific Ocean
We have examined the impact of MJO on total precipitable water (TPW) and total column ozone (TCO) in the tropics using the ERA-Interim reanalysis dataset from 1979-2013
Summary
Tropical atmospheric circulations are controlled by the large-scale convective system varying in space and time, which includes the equatorial planetary waves [1][2][3], intra-seasonal oscillation (MJO) [4], inter-annual oscillation ENSO [5], and decadal to multidecadal oscillation. MJO is characterized by an eastward moving 'pulse' of large-scale convection system elongated from the Indian Ocean to the Pacific Ocean [6]. This oscillation has an average phase speed of about 5 m s-1 and a period of about 30-90 days [7]. Previous research showed that the MJO can be identified by parameters of convection and other variables in the atmosphere, such as outgoing longwave radiation (OLR), precipitation, sea surface temperature, variations in wind, water vapor, and ozone [8][9][10]
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