Buoy observations of the atmosphere along the west coast of the United States, 1981–1990

Abstract

The distribution of statistical properties of the meteorological and sea surface temperature fields along the west coast of the United States is described based on 10‐yearlong observations from buoys deployed by the National Data Buoy Center. The observations suggest that properties vary differently in each of three different regions along the coast: the Southern California Bight which remains sheltered from strong wind forcing throughout the year; the central and northern California coast up to Cape Mendocino, the site of persistent equatorward winds; and the Oregon‐Washington coast, where traveling cyclones and anticyclones produce vigorous and variable forcing. Over most of the region the variance in the wind speed is roughly equally divided between the annual cycle and the synoptic forcing, corresponding to periods between 5 and 50 cycles per year. Two seasons, summer and winter, are sufficient to describe the annual cycle. During the summer, two distinct wind speed maxima occur along the coast, one near Point Conception and the other off northern California, between Point Reyes and Point Arena. In the winter a single maximum occurs, located near Point Conception. The atmospheric pressure generally increases with latitude along the coast, but the annual cycle of atmospheric pressure has a different phase, depending on location; off the coast of California, highest pressures are found during the winter, while off Oregon and Washington, the highest pressures occur during the summer. Fluctuations in air and sea temperature are highly correlated, and the sea temperature is usually higher than the air temperature, in the winter. Examination of vertical soundings of the atmosphere at Oakland, Vandenberg Air Force Base and San Diego during the same period of time reveals that a well‐defined inversion separates the marine boundary layer (MBL) from the free atmosphere above nearly 90% of the time during the summer and half the time during the winter. Station soundings consistently overestimate the MBL thickness, but the results do suggest that the MBL is supercritical part of the time in the vicinity of the three sites. An attempt is made to examine the interannual variability and compare it to the Southern Oscillation index, although the results are limited because the record length is short compared with interannual timescales. Spatially averaged temperature anomalies increase during winter 1982–1983, coincident with the large El Niño event.

Transport and retention in an upwelling region: The role of across-shelf structure

“…During the winter survey periods winds were weaker and more variable ( Figure 3); for example from Jan-April 2002, the mean wind strength (stress) was ∼ 1.6 ms −1 (∼ 0.04 Nm −2 ) and the standard deviations were large (Dorman et al, 2005). These results are comparable to those found by Dorman and Winant (1995) who analyzed 10 years of atmospheric data from NDBC 46013 and found the mean winter strength to be ∼ 1.8 ms −1 while the summer mean was ∼ 6.4 ms −1 .…”

“…The upwelling region off the coast of northern California (37−40 • N) experiences the strongest summertime wind forcing along the US west coast (Dorman and Winant, 1995). This cycle of wind forcing and the upwelling response has been well studied in the past few decades.…”

On the skill of seasonal sea surface temperature forecasts in the California Current System and its connection to ENSO variability

“…Given that atmospheric forcing varies dramatically between regions within the CCS (Checkley and Barth 2009;Dorman and Winant 1995), it is reasonable to expect that the predictability derived from that forcing will vary as well. Furthermore, applications of seasonal SST forecasts often occur on scales smaller than the entire CCS (e.g., Kaplan et al 2016;Tommasi et al 2017).…”

“…3.4 we further divide the CCS into northern, central, and southern CCS regions, with divisions at Cape Mendocino (~40.5°N) and Point Conception (~34.5°N). These sub-regions capture distinct physical and biological regimes within the CCS, and are delineated according to the prevailing atmospheric forcing and ocean dynamics (Checkley and Barth 2009;Dorman and Winant 1995).…”

Limacina helicinashell dissolution as an indicator of declining habitat suitability owing to ocean acidification in the California Current Ecosystem

“…The survey encompassed three broad regions typified by regional differences in wind and temperature patterns that potentially affect the dynamics of V ar [42]. The region north of Cape Mendocino (40.58 N) was denoted as the northern region, between Cape Mendocino and Point Conception (34.58 N) as the central region, and southward from Point Conception (32.48 N) as the southern region (figure 1c).…”