Evaluation of the Temperature Trend and Climate Forcing in the Pre- and Post Periods of Satellite Data Assimilation - Satellite-based Applications on Climate Change - page 58

Fig. 4.5 Temperature response in the stratosphere (70-100 hpa) to the forcing in the two periods
of 1979-2002 and 1958-1978: ( a , b ) ENSO; ( c , d ) QBO; ( e , f ) stratospheric aerosol. The shaded
areas indicate the statistical significance at the 95% level
The shaded areas indicate that the temperature response to ENSO exceeds the
statistical significance test at the 95% confidence level.
Second, the stronger signal response to the QBO forcing appeared over the
tropical and Arctic zones. However, the amplitudes are different in the two periods
(Fig. 4.5c, d ). The result clearly reproduced the negative relationship between the
QBO forcing and stratospheric temperature over the Arctic (Holton and Tan 1980 )
where the Arctic stratosphere is indeed warmer under easterly QBO conditions and
colder under westerly QBO conditions. Moreover, a remarkable zonal homoge-
neous positive anomaly exceeding the 95% significance test is observed in the
tropical areas, especially in the period of 1958-1978.
Third, the response to the stratospheric aerosols (Fig. 4.5e, f ) has a similar
pattern in the two periods with positive contributions in the tropical and subtropical
areas. However, the response is significantly different over both polar regions in the