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White, WB, Cayan DR.  2000.  A global El Nino-Southern Oscillation wave in surface temperature and pressure and its interdecadal modulation from 1900 to 1997. Journal of Geophysical Research-Oceans. 105:11223-11242.   10.1029/1999jc900246   AbstractWebsite

Zonal wavenumber frequency spectra of sea surface temperature (SST) anomalies along the equator in the Indo-Pacific basin For the 98 years from 1900 to 1997 and of surface temperature (ST) and sea level pressure (SLP) anomalies extending around the globe along 10 degrees N for the 48 years from 1950 to 1997 display significant peak spectral energy density for standing and eastward propagating waves of 3-7 year periods and 120 degrees-360 degrees zonal wavelengths, The global standing wave is the familiar Southern Oscillation, but the global propagating wave represents a new paradigm for the El Nino-Southern Oscillation (ENSO). Global distributions of the phase velocities for this global ENSO wave finds covarying SLP and ST anomalies propagating eastward along the mean path of the Intertropical Convergence Zone (ITCZ), with the global zonal wavenumber 1 (2) component taking similar to 4 (6) years to cross the tropical Indian, Pacific, and Atlantic Oceans at a zonal average speed of 90 degrees (60 degrees) longitude per year. Along this path the interannual SST acid SLP anomalies are directly out of phase. Since thermocline depth anomalies underneath the ITCZ in the Pacific Ocean propagate westward [White et al. 1985], we view the global ENSO wave as a slow coupled SST wave trapped onto the ITCZ. Separating the global ENSO wave from the Southern Oscillation using complex empirical orthogonal function analysis finds the amplitude of the propagating wave to be half that of the standing wave, with the former (latter) accounting for one third (two thirds) of the interannual variability in Nino-3 SST and SLP indices during the 1980s. The global ENSO wave is shown to be responsible for the eastward propagation of covarying zonal surface wind and thermocline depth anomalies across the equatorial Pacific Ocean and through this mechanism is able to influence both the phasing and intensity of El Nino. Examining the persistence of the global ENSO wave from 1900 to 1997 finds it and the intensity of El Nino in the eastern equatorial Pacific Ocean modulated by interdecadal change, Both were strong (weak or absent) during decades of global tropical cooling (warming).

White, WB, Cayan DR, Lean J.  1998.  Global upper ocean heat storage response to radiative forcing from changing solar irradiance and increasing greenhouse gas/aerosol concentrations. Journal of Geophysical Research-Oceans. 103:21355-21366.   10.1029/98jc01477   AbstractWebsite

We constructed gridded fields of diabatic heat storage changes in the upper ocean from 20 degrees S to 60 degrees N from historical temperature profiles collected from 1955 to 1996. We filtered these 42 year records for periods of 8 to 15 years and 15 to 30 years, producing depth-weighted vertical average temperature (DVT) changes from the sea surface to the top of the main pycnocline. Basin and global averages of these DVT changes reveal decadal and interdecadal variability in phase across the Indian, Pacific, Atlantic, and Global Oceans, each significantly correlated with changing surface solar radiative forcing at a lag of 0 +/- 2 years. Decadal and interdecadal changes in global average DVT are 0.06 degrees +/- 0.01 degrees K and 0.04 degrees K +/- 0.01 degrees K, respectively, the same as those expected from consideration of the Stefan-Boltzmann radiation balance (i.e., 0.3 degrees K per W m(-2)) in response to 0.1% changes in surface solar radiative forcing of 0.2 W m(-2) and 0.15 W m(-2), respectively. Global spatial patterns of DVT changes are similar to temperature changes simulated in coupled ocean-atmosphere models, suggesting that natural modes of Earth's variability are phase-locked to the solar irradiance cycle. A trend in global average DVT of 0.15 degrees K over this 42 year record cannot be explained by changing surface solar radiative forcing. But when we consider the 0.5 W m(-2) increase in surface radiative forcing estimated from the increase in atmospheric greenhouse gas and aerosol (GGA) concentrations over this period [Intergovernmental Panel on Climate Change, 1995], the Stefan-Boltzmann radiation balance yields this observed change. Moreover, the sum of solar and GGA surface radiative forcing can explain the relatively sharp increase in global and basin average DVT in the late 1970's.

Gershunov, A, Cayan DR, Iacobellis SF.  2009.  The great 2006 heat wave over California and Nevada: Signal of an increasing trend. Journal of Climate. 22:6181-6203.   10.1175/2009jcli2465.1   AbstractWebsite

Most of the great California-Nevada heat waves can be classified into primarily daytime or nighttime events depending on whether atmospheric conditions are dry or humid. A rash of nighttime-accentuated events in the last decade was punctuated by an unusually intense case in July 2006, which was the largest heat wave on record (1948-2006). Generally, there is a positive trend in heat wave activity over the entire region that is expressed most strongly and clearly in nighttime rather than daytime temperature extremes. This trend in nighttime heat wave activity has intensified markedly since the 1980s and especially since 2000. The two most recent nighttime heat waves were also strongly expressed in extreme daytime temperatures. Circulations associated with great regional heat waves advect hot air into the region. This air can be dry or moist, depending on whether a moisture source is available, causing heat waves to be expressed preferentially during day or night. A remote moisture source centered within a marine region west of Baja California has been increasing in prominence because of gradual sea surface warming and a related increase in atmospheric humidity. Adding to the very strong synoptic dynamics during the 2006 heat wave were a prolonged stream of moisture from this southwestern source and, despite the heightened humidity, an environment in which afternoon convection was suppressed, keeping cloudiness low and daytime temperatures high. The relative contributions of these factors and possible relations to global warming are discussed.