A Climatological Spectral Study for Diagnosing the Solar 11-Year Signal in the Northern Hemisphere Atmosphere

Ming Chen [ming.chen@noaa.gov],IMSG at NOAA/NESDIS, Camp Springs, Maryland;and Alfred M. Powell, Jr. [al.powell@noaa.gov], NOAA/NESDIS/ORA.

            An extensive spectral analysis is carried out to search for the possible Sun-Earth connections using 50-yr NCEP/NCAR reanalysis data. A Fourier transformation is first applied latitude by latitude to get zonal waves of different spatial scales. The time series of the amplitude (energy) of each wave is filtered to isolate low and high frequency planetary/Rossby waves. From the viewpoint of linear wave theory, these waves are assumed to carry atmospheric energy derived from the original sources and the atmospheric response to the source functions. By analyzing the different atmospheric fields (height, temperature, wind) for planetary wave energy variations, insight into the wave energy processes and their sources can be obtained. The temporal change of wave amplitude is closely related to the source energy change, such as boundary condition changes or nonlinear adjustment of background state (energy exchange from different scales). Since solar output variations are small compared to the total solar output (solar constant), it is generally assumed solar variations will exert their influence through existing dynamic or thermodynamic sources identified as sensitive to solar variation, for example: ozone change or heating, QBO, etc. This analysis uses time series analysis and correlation statistics of the relevant carrier-wave energy to evaluate the likelihood of a solar forced process. Several conclusions implicating solar impacts on climate were drawn including a strong Northern Hemisphere February correspondence. The identified solar-associated planetary wave changes are expected to improve the understanding of potential Sun-Earth connection mechanisms that could be implemented in a synoptic or climatic model to enhance the model prediction.