Characteristic Features of Estuarine Circulation as Represented in the Mersey Estuary1

Measurements have been made at a number of stations in the Narrows of the Mersey estuary of the residual, or nontidal, flow and the salinity distribution under a wide variety of conditions. The data have been analyzed in terms of a stratification‐circulation diagram as introduced by Hansen and Rattray. In this way the characteristics of the Mersey estuary have been compared with those of other estuaries and with the features of Hansen and Rattray’s theoretical model. In the central stretch of the Narrows, the density current circulation is highly developed and the advective mode accounts for about 75% of the upstream transfer of salt. Toward both the upstream and downstream ends of the Narrows, beyond which the estuary becomes wider and shallower, the advective transfer becomes less important than the diffusive processes. The value of the stratification‐circulation diagram in representing the conditions in an estuary and interpreting them in terms of the underlying processes is confirmed.