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Iacobellis, SF, Cayan DR.  2013.  The variability of California summertime marine stratus: Impacts on surface air temperatures. Journal of Geophysical Research-Atmospheres. 118:9105-9122. AbstractWebsite

This study investigates the variability of clouds, primarily marine stratus clouds, and how they are associated with surface temperature anomalies over California, especially along the coastal margin. We focus on the summer months of June to September when marine stratus are the dominant cloud type. Data used include satellite cloud reflectivity (cloud albedo) measurements, hourly surface observations of cloud cover and air temperature at coastal airports, and observed values of daily surface temperature at stations throughout California and Nevada. Much of the anomalous variability of summer clouds is organized over regional patterns that affect considerable portions of the coast, often extend hundreds of kilometers to the west and southwest over the North Pacific, and are bounded to the east by coastal mountains. The occurrence of marine stratus is positively correlated with both the strength and height of the thermal inversion that caps the marine boundary layer, with inversion base height being a key factor in determining their inland penetration. Cloud cover is strongly associated with surface temperature variations. In general, increased presence of cloud (higher cloud albedo) produces cooler daytime temperatures and warmer nighttime temperatures. Summer daytime temperature fluctuations associated with cloud cover variations typically exceed 1 degrees C. The inversion-cloud albedo-temperature associations that occur at daily timescales are also found at seasonal timescales.

Sumargo, E, Cayan DR.  2017.  Variability of cloudiness over mountain terrain in the western United States. Journal of Hydrometeorology. 18:1227-1245.   10.1175/jhm-d-16-0194.1   AbstractWebsite

This study investigates the spatial and temporal variability of cloudiness across mountain zones in the western United States. Daily average cloud albedo is derived from a 19-yr series (1996-2014) of half-hourly Geostationary Operational Environmental Satellite (GOES) images. During springtime when incident radiation is active in driving snowmelt-runoff processes, the magnitude of daily cloud variations can exceed 50% of long-term averages. Even when aggregated over 3-month periods, cloud albedo varies by +/- 10% of long-term averages in many locations. Rotated empirical orthogonal functions (REOFs) of daily cloud albedo anomalies over high-elevation regions of the western conterminous United States identify distinct regional patterns, wherein the first five REOFs account for; similar to 67% of the total variance. REOF1 is centered over Northern California and Oregon and is pronounced between November and March. REOF2 is centered over the interior northwest and is accentuated between March and July. Each of the REOF/rotated principal components (RPC) modes associates with anomalous large-scale atmospheric circulation patterns and one or more large-scale teleconnection indices (Arctic Oscillation, Nino-3.4, and Pacific-North American), which helps to explain why anomalous cloudiness patterns take on regional spatial scales and contain substantial variability over seasonal time scales.

Cayan, DR.  1992.  Variability of latent and sensible heat fluxes estimated using bulk formulas. Atmosphere-Ocean. 30:1-42. AbstractWebsite

The spatial and temporal variability of monthly average latent and sensible heat flux over the oceans is explored. Monthly flux anomalies are estimated using bulk formulae applied to COADS marine data over 1946-1986. Emphasis is on behaviour during fall and winter over the well sampled North Atlantic and North Pacific oceans, but available data from the Indian Ocean, from the tropics and from the Southern Hemisphere are also included Random observation errors and random weather sampling errors are reduced by averaging several observations together. Biases in the observations and in the bulk formulae are not automatically reduced by averaging, but because the mean of the fluxes is subtracted to provide the anomalies, the non-time-varying biases are diminished Largest latent flux anomalies occur from the tropics to middle latitudes, and largest sensible flux anomalies appear in middle-to-high latitudes. In mid-latitudes, monthly latent and sensible flux anomalies are strongly correlated, so that they tend to be reinforcing. The bulk parametrizations indicate that the latent and sensible flux anomalies typically outweigh those of the radiative fluxes, except in the tropics and in the summer extratropics where net solar flux variations become important. An analysis of variance, which identifies the dominant contributions by the fundamental marine variables, yields results that emphasize the importance of the mean values, as well as the anomalies of these variables, in creating latent and sensible flux anomalies. Although they contain small-scale "noise", there is a marked signal in the flux anomalies that is spatially organized and quite strongly related to the monthly atmospheric circulation. The first four rotated empirical orthogonal functions (REOFs) of the sum of the latent and sensible flux anomalies account for about half of the total variance in the North Atlantic and North Pacific basins during winter months. The REOFs have magnitudes that represent anomalies that typically exceed 50 W m-2 over substantial portions of the ocean basins. Links to the atmospheric circulation also indicate a short-period climate signal. Correlations of the amplitudes of the REOFs of the fluxes with the sea-level pressure field exhibit patterns that strongly resemble frequently occurring modes of monthly circulation anomalies. In the extratropics during winter, the atmospheric circulation affects the Bowen ratio (sensible flux/latent flux). When the wind is more equatorward or more continental than normal, the Bowen ratio increases.