Abstract
To better understand the response of a buoyant coastal plume to wind-induced upwelling, a two-dimensional theory is developed that includes entrainment. The primary assumption is that competition between wind-driven vertical mixing and lateral buoyancy forcing in the region where the isopycnals slope upward to intersect the surface results in continual entrainment at the offshore edge of the plume. The theory provides estimates of the buoyant plume characteristics and offshore displacement as a function of time t, given the wind stress, the characteristics of the buoyant plume prior to the onset of the wind forcing, and a critical value for the bulk Richardson number (Ric). The theory predicts that, for t̂ ≡ t/ts, the plume density anomaly decreases as (1 + t̂)−1, the thickness increases as (1 + t̂)1/3, the width increases as (1 + t̂)2/3, and the plume average entrainment rate decreases as (1 + t̂)−2/3. Here ts = 2Ao/(
Corresponding author address: Dr. Steve Lentz, MS21, Woods Hole Oceanographic Institution, Woods Hole, MA 02543. Email: slentz@whoi.edu