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The characteristics of a convective internal boundary layer (CIBL) documented offshore of the US East Coast during the field campaign CASPER-EAST has been examined using field observations, a coupled mesoscale model (i.e., Navy's COAMPS) simulation, and a couple of surface-layer resolving large eddy simulations (LES). The Lagrangian modeling approach has been adopted with the LES domain being advected from a cool and rough land surface to a warmer and smoother sea surface by the mean offshore winds in the CIBL. The surface fluxes from the LES control simulation are in reasonable agreement with field observations, and the general CIBL characteristics are consistent with previous studies. According to the LES simulations, in the nearshore adjustment zone (i.e., fetch < 8 km), the low-level winds and surface friction velocity increase rapidly, and the mean wind profile and vertical velocity skewness in the surface layer deviates substantially from the Monin-Obukhov similarity theory (MOST) scaling. Further offshore, the nondimensional vertical wind shear and scalar gradients and higher-order moments are consistent with the MOST scaling. An elevated turbulent layer is present immediately below the CIBL top, associated with the vertical wind shear across the CIBL top inversion. Episodic shear instability events occur with a timescale between 10-30 min., leading to the formation of elevated episodic maxima in turbulence kinetic energy and momentum fluxes. During these events, the turbulence kinetic energy production exceeds the dissipation, suggesting that the CIBL remains in non-equilibrium.