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A statistically significant atmospheric signal, which represents the influence of solar radiation changes on our climate, is found in global data (1958–2003). Using a nonlinear, nonstationary time series analysis, called empirical mode decomposition, it is shown that atmospheric temperatures and geopotential heights are composed of five global oscillations and a trend. The fourth mode is synchronized with the 11‐year solar flux almost everywhere in the lower atmosphere. Statistical tests show that this signal is different from noise, indicating that there is enhanced warming in the troposphere during times of increased solar radiation.

Abstract.A QBO (quasi-biennial oscillation) signal is found in 150-year, Northern Hemisphere, surface air temperatures which have been projected onto an annular mode at the surface. The signal is tied to the equatorial QBO by demonstrating coherence in the extratropical stratosphere and tracing the signal, using the annular modes as a filter, down through the atmosphere to the surface. Then the statistical significance of the surface signal is established.

The k-means cluster technique is used to examine 43 yr of daily winter Northern Hemisphere (NH) polar stratospheric data from the 40-yr ECMWF Re-Analysis (ERA-40). The results show that the NH winter stratosphere exists in two natural well-separated states. In total, 10% of the analyzed days exhibit a warm disturbed state that is typical of sudden stratospheric warming events. The remaining 90% of the days are in a state typical of a colder undisturbed vortex. These states are determined objectively, with no preconceived notion of the groups. The two stratospheric states are described and compared with alternative indicators of the polar winter flow, such as the northern annular mode. It is shown that the zonally averaged zonal winds in the polar upper stratosphere at ∼7 hPa can best distinguish between the two states, using a threshold value of ∼4 m s−1, which is remarkably close to the standard WMO criterion for major warming events. The analysis also determines that there are no further divisions within the warm state, indicating that there is no well-designated threshold between major and minor warmings, nor between split and displaced vortex events. These different manifestations are simply members of a continuum of warming events.

The Indian Ocean Dipole (IOD) mode and El Niño/Southern Oscillation (ENSO) exhibit a substantial correlation during boreal autumn. Although they are separate phenomena, coupling occurs under certain conditions. This study reveals that ENSO‐related variability extends into the Indian Ocean, led by a developed South Indian Ocean (SIO) anticyclone, during periods of low solar (LS) activity. During periods of high solar (HS) activity, anomalous sea surface temperatures are confined to the Pacific with little amplification of the anticyclone in the South Indian Ocean. The direct cause of the difference in the SIO anticyclone arises from a shift in the location of the descending branch of the anomalous Walker circulation. This may be attributable to a change in the background Indian Ocean monsoon circulation which can be modulated by changes in solar irradiance.

[1] We present a simple method to make multi-year surface temperature forecasts using the climate change simulations of the CMIP3 database prepared for the IPCC AR4 report. By calibrating the multi-model ensemble mean with current observations, we are able to make skillful interannual forecasts of mean temperatures. The method is validated using extensive hindcast experiments and is shown to perform favorably compared to a recent forecast method based on a global circulation model with assimilated initial conditions. Five year forecasts for the global mean temperature, the Northern Hemispheric mean temperature and the summer sea surface temperatures (SSTs) in the main development region for hurricanes (MDR) are presented. Citation: Laepple, T., S. Jewson, and K. Coughlin (2008), Interannual temperature predictions using the CMIP3 multi-model ensemble mean, Geophys. Res. Lett., 35, L10701,

[1] Baldwin and Dunkerton [1999] found that negative northern annular mode (NAM) anomalies sometimes descend all the way from the stratosphere into the lower troposphere. However, no viable mechanism has been proposed so far to account for the magnitude of the anomalies in the denser troposphere. Further, analysis shows that the character of the anomaly changes across the tropopause. Above the tropopause the NAM pattern is approximately zonal, and its descent represents the descent of decelerated zonal mean winds. This stratospheric change is explainable using theories similar to those for the descent of the zero-wind line associated with a major stratospheric sudden warming. However, such a reversal in the zonal mean wind rarely reaches the denser troposphere. The descent of the NAM anomalies into the troposphere may be implying a different relationship between the stratosphere and the troposphere. We note that in the troposphere the structure of the NAM has a large wave component. In some cases, this wave component appears to react to the decelerated wind configuration aloft. Here we show observations of the wave component and the zonal mean component in comparison to corresponding NAM events to show that the wave response is a sizable component of the NAM anomaly in the troposphere. We will also present a simple model calculation to show that tropospheric waves forced by topography can react to changing stratospheric winds. These tropospheric waves can project directly onto the tropospheric NAM patterns and produce anomalies in the index which appear to be connected to the negative NAM anomalies in the stratosphere.Citation: Coughlin, K., and K. K. Tung (2005), Tropospheric wave response to decelerated stratosphere seen as downward propagation in northern annular mode,

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