Temporal and Spatial Characteristics of AIRS and CERES OLR Climatologies
and Anomaly Time Series
Abstract
This paper compares the characteristics of the monthly mean AIRS
Version-6 and CERES_EBAF Edition 4.0 OLR data sets over a 14-year
overlap period, September 2002 through August 2016. These comparisons
include spatial plots of monthly mean OLR climatologies and spatial
plots of OLR Average Rates of Change (ARCs), representative of the
slopes of the linear least squares fits to anomaly time series. This
paper also compares spatial plots of El Niño Correlations (ENCs) of the
AIRS OLR and CERES OLR anomaly time series. ENCs represent temporal
correlations of anomaly time series with an El Niño Index that we define
in this paper. In addition, we show ARCs and ENCs of select derived AIRS
geophysical parameters that help explain OLR variability in space and
time. There are separate AIRS data sets that use data observed only in
ascending Aqua orbits (AIRS) and data observed only in descending Aqua
orbits (AIRS). An additional data set of AIRS products exists based on
observations made in both orbits (AIRS). There is excellent agreement
between the ARCs of CERES OLR and the ARCs of AIRS OLR down to the 1˚ by
1˚ longitude spatial scale. The AIRS OLR product displays a positive
global mean monthly mean bias compared to CERES OLR of roughly 3.0 W/m
that is essentially constant in space and time. The largest differences
between AIRS OLR and CERES OLR monthly climatologies and anomaly time
series occur in regions where the diurnal differences of AIRS OLR are
largest.