Spatial Correlations of Anomalies of Tropospheric Temperature and Water Vapor, Cloud Cover, and Outgoing Longwave Radiation with the El Niño Index

Abstract:

The AIRS Science Team Version-6 retrieval algorithm is now operational at the Goddard DISC. AIRS Version-6 monthly mean level-3 products have been generated on a one degree by one degree spatial scale for the 12 year period September 2002 through August 2014. AIRS Version-6 products are significantly improved over those obtained previously. Among the products retrieved from AIRS radiance observations are: surface skin temperature and atmospheric temperature profile; atmospheric water vapor profile; cloud top pressure; and longwave radiative effective cloud fraction. Outgoing Longwave Radiation (OLR) is subsequently generated via radiative transfer calculations so as to be consistent with the other products retrieved from AIRS.

In this presentation, we will show AIRS Version-6 area weighted anomaly time series over the time period September 2002 through August 2014 of atmospheric temperature and water vapor profiles as a function of height. These anomaly time series show very different behaviors in the stratosphere and in the troposphere. Tropical mean stratospheric temperature anomaly time series are very strongly influenced by the Quasi-Biennial Oscillation (QBO) with large anomalies that propagate downward from 1 mb to 100 mb with a period of about two years. AIRS stratospheric temperature anomalies are in good agreement with those obtained by MLS over a common period. Tropical mean tropospheric temperature profile anomalies appear to be totally disconnected from those of the stratosphere and closely follow El Niño/ La Niña activity.

Most of this presentation will concentrate on the spatial distributions of short term 12 year “trends” of the anomaly time series of tropospheric temperature and water vapor profiles, cloud cover, and OLR, and the correlations of these anomaly time series with the El Niño Index, which we call ENCs. The spatial distributions of these ENCs explain the close connection between anomalies of global mean, and especially tropical mean, mid-tropospheric temperature and water vapor concentrations with the El Niño Index. They also explain why global mean, and especially tropical mean, values of OLR, as depicted by both AIRS and CERES, also are closely related to El Niño activity.