The temporal, vertical, and alongshore variation in inner‐shelf temperature, T, across subtidal (ST), diurnal (DU), and semidiurnal (SD) bands on coastlines with headlands is not understood. Inner‐shelf T was observed with 20 moorings in 9‐ to 16‐m depth with high vertical density during Fall 2017 along 50 km of central California coastline with headlands. The ST‐first empirical orthogonal function is largely barotropic. ST warm water events are associated with northward‐propagating buoyant plumes and onshore advection of offshore water, with headland effects, particularly for stronger events. Previous plume arrival criteria are northward propagation biased. The DU vertical structure was mixed barotropic and linear baroclinic, without surface extrema. Inner‐shelf DU‐band temperature variability was always evident, largest north of and weakest south of two headlands. The DU‐T envelope was not modulated by ST stratification and was not linked to the modeled DU‐wind envelope. North of one headland, the alongshore first complex empirical orthogonal function of DU temperature has a previously unobserved southward 2‐m/s phase propagation, even though DU frequency is subcritical, that is, not wind forced. A frictional subcritical wave mechanism is proposed for the DU propagation. The SD‐T vertical structure varies alongshore, suggesting at different locations linear internal waves and nonlinear cold bores. SD‐T variability was incoherent with barotropic tides and decorrelates alongshore in 7.5 km, contrasting with a few kilometers offshore. The SD depth‐averaged energy varied strongly alongshore particularly north and south of the headlands, and stronger and weaker SD energy was linked to nonlinear and linear baroclinic vertical structures, respectively, which are headland influenced.

Abstract. An analysis is presented of the failed redevelopment of ex-Gaston during the 2010 PREDICT field campaign based on the European Centre for Medium Range Weather Forecast (ECMWF) analyses. We analyze the dynamics and kinematics of ex-Gaston to investigate the role of dry, environmental air in the failed redevelopment. The flow topology defined by the calculation of particle trajectories shows that ex-Gaston's pouch was vulnerable to dry, environmental air on all days of observations. As early as 12:00 UTC 2 September 2010, a dry layer at and above 600 hPa results in a decrease in the vertical mass flux and vertical relative vorticity. These findings support the hypothesis that entrained, dry air near 600 hPa thwarted convective updraughts and vertical mass flux, which in turn led to a reduction in vorticity and a compromised pouch at these middle levels. A compromised pouch allows further intrusion of dry air and quenching of subsequent convection, therefore hindering vorticity amplification through vortex tube stretching. This study supports recent work investigating the role of dry air in moist convection during tropical cyclogenesis.

<p><strong>Abstract.</strong> An analysis is presented of the failed re-development of ex-Gaston during the 2010 PREDICT field campaign based on the European Centre for Medium Range Weather Forecast (ECMWF) analyses. We analyze the dynamics and kinematics of ex-Gaston to investigate the role of dry, environmental air in the failed redevelopment. The flow topology defined by the calculation of particle trajectories shows that ex-Gaston’s pouch was vulnerable to dry, environmental air on all days of observations. As early as 12:00 UTC 2 September 2010, a dry layer at and above 600 hPa results in a decrease in the vertical mass flux and vertical, relative vorticity. These findings support the hypothesis that entrained, dry air near 600 hPa thwarted convective updraughts and vertical mass flux, which in turn led to a reduction in vorticity and a compromised pouch at these middle levels. A compromised pouch allows further intrusion of dry air and inhibits vorticity amplification. This study supports recent work investigating the role of dry air in moist convection during tropical cyclogenesis.</p>

Cross-shore heat flux (CHF) spatiotemporal variability in the subtidal (ST), diurnal (DU), and semidiurnal (SD) bands is described for 35 days (summer 2015) from co-located vertical measures of temperature and currents obtained by moorings deployed from 50 to 7 m water depths near Pt. Sal, California. The CHF is largest in the ST and SD bands, with nearly zero contribution in the DU band. The sum of CHF and surface heat flux (SHF) account for 31% and 17% of the total change in heat storage on the midshelf and inner shelf respectively. The ST CHF for the midshelf and inner shelf is mostly negative and is correlated with upwelling-favorable winds. A mostly positive SD CHF on the midshelf and inner shelf decreases linearly in the shoreward direction, is correlated with wind relaxations, and is attributed to warm-water internal tidal bores (WITBs) that are observed to propagate to the edge of the surf zone. A negative SD CHF is correlated with upwelling-favorable winds on the midshelf at 15-25 hr time lags, and is believed to be associated with cold-water internal tidal bores. The WITBs have characteristics of progressive waves on the midshelf and transition to partially standing waves on the inner shelf potentially reducing the SD CHF contribution on the inner shelf. Heat accumulation over the midshelf and inner shelf is primarily driven by WITBs and SHF which is largely balanced by cumulative cooling by ST processes over the midshelf and cumulative cooling by AHF over the inner shelf.

Diurnal‐band temperature (DU‐T) variability is investigated over 30 days from measures of temperature over the vertical obtained by 78 moorings deployed in the Santa Monica Basin near Pt. Sal (PS), California. DU‐T variability accounts for 3.6%–23% of the total variability. Vertical empirical orthogonal function mode‐1 DU‐T variability accounts for an average of 86% of the total vertical DU‐T variability at each mooring, is greatest north of PS where its vertical structure is baroclinic, and weakest south of PS where its vertical structure is surface intensified. Spatial complex empirical orthogonal function mode‐1 DU‐T accounts for 73% of the total DU‐T over the region, reveals an onshore baroclinic DU‐T propagation of ∼0.5 m/s, and a previously observed equatorward baroclinic DU‐T propagation of ∼1.9 m/s along the coast north of PS. Dominant vertical mode‐1 diurnal‐band baroclinic velocity (DU‐w) variability at each mooring exhibits a two‐layer structure that is 180° out of phase with maxima near the surface and the bottom, and resembles the DU‐T propagation. DU‐T variability mechanisms include wind‐forced deepening of the surface mixed layer, inertial motions, upwelling, and barotropic and baroclinic tides. Among these concomitant diurnal mechanisms, wind‐driven inertial motions are likely the primary mechanism influencing DU‐T variability during upwelling‐favorable conditions owing to coherence between observed DU‐w and the predicted inertial response to wind‐forcing. Further, spatial mode‐1 DU‐T is correlated and coherent with spatial mode‐1 DU‐w and diurnal wind‐forcing. In addition to describing predominant DU‐T variability patterns, these findings have important implications regarding spatial patterns in biological recruitment, transport, and settlement.