Simulation of Solar Cycle Response in Tropical Total Column Ozone using SORCE Irradiance
King-Fai Li1 [kfl@gps.caltech.edu], Xun Jiang2, Mao-Chang Liang3, Yuk L. Yung1
1
2
3
California Institute of Technology, Pasadena, California
University of Houston, Texas
Academia Sinica, Taiwan
The solar-cycle signal of tropical column ozone (XO3) in the Whole Atmosphere
Community Climate Model (WACCM) model has been examined using solar spectral
irradiance (SSI) estimated from the Naval Research Laboratory (NRL) solar model and that
from recent satellite measurements observed by the Solar Radiation and Climate Experiment
(SORCE). Four experiments have been conducted with NRL/SORCE SSI and
climatological/realistic sea surface temperatures and ice, and all other variability is fixed to
test the robustness of the simulated solar response in O3 against the presence of El
Niño/Southern oscillation (ENSO). We found that potential aliasing effects from ENSO
occurs below 20 km where tropical O3 concentration is low and has little impact (less than
~0.6 DU/100F10.7) on the regressed XO3 response. In the tropical region 24ºS–24ºN, using the
SORCE SSI as a model input leads to a solar-cycle response of ~5.4 DU/100F10.7, which
agrees with those obtained from the merged TOMS/SBUV satellite observations. The
resultant vertical O3 response agrees with previous satellite measurements in the lower
stratosphere but the negative response in the upper stratosphere disagrees with the observed.
In contrast, the XO3 responses is ~3 DU/100F10.7, which is ~half of that obtained using
SORCE SSI but agrees better with the SAGE and ground-based observations. The resultant
vertical O3 response agrees with previous satellite measurements in the upper stratosphere
but the lower stratospheric response is much weaker than the observed. This presents a
dilemma to our current understanding of stratospheric O3 response to UV perturbations.