Analyses of Doppler lidar data reveal sea breezes occurring on two different depth and time scales at Monterey Bay, California, on a day with offshore gradient flow indicated before sunrise and after sunset. The lidar data used in this study consist of vertical cross sections and profiles of the westerly, onshore wind component u. In the morning after 0900 PST a shallow sea breeze formed, which reached a depth of 300 m by noon. Starting in early afternoon a deeper sea-breeze layer formed in the lowest kilometer, and by late afternoon the shallow sea breeze blended into the deeper sea breeze and was no longer evident. Maximum speeds of 6 m s−1 in the shallow sea breeze occurred at the surface, whereas those in the deep sea breeze (also 6 m s−1) were about 300 m above the surface. It is hypothesized that the shallow sea breeze is a local phenomenon responding to a more local temperature contrast between the sea and the region between the ocean and the mountain ranges. The deeper sea breeze, on the ... Abstract Analyses of Doppler lidar data reveal sea breezes occurring on two different depth and time scales at Monterey Bay, California, on a day with offshore gradient flow indicated before sunrise and after sunset. The lidar data used in this study consist of vertical cross sections and profiles of the westerly, onshore wind component u. In the morning after 0900 PST a shallow sea breeze formed, which reached a depth of 300 m by noon. Starting in early afternoon a deeper sea-breeze layer formed in the lowest kilometer, and by late afternoon the shallow sea breeze blended into the deeper sea breeze and was no longer evident. Maximum speeds of 6 m s−1 in the shallow sea breeze occurred at the surface, whereas those in the deep sea breeze (also 6 m s−1) were about 300 m above the surface. It is hypothesized that the shallow sea breeze is a local phenomenon responding to a more local temperature contrast between the sea and the region between the ocean and the mountain ranges. The deeper sea breeze, on the ...