Hydrographic observations and model results from a PRISMA drift experiment

Abstract

A drift experiment was conducted from 23 to 29 April 1991 in the central western part of the German Blght as part of the German research program PRISMA. Observed hydrograph~c time series and results from a numerical model are presented. The discussion focuses on the problem of whether the drift buoy used was suitable for marking a 'selected water body' in order to study specific processes. Based upon the data and the model outcome, the experiment had to be divided into 2 phases. During the first phase the drift buoy was situated in denser water with relatively low concentrations of suspended particulate matter (SPM) and phytoplankton. On 26-27 April, a storm event initiated the second phase. The buoy was then forced to deviate from its expected position into a water mass of a more coastal type characterized by slightly h~g h e r temperatures, lower salinity and lower transmission. Concentrations of phytoplankton and SPM increased. The passage of a weak salinity front between 2 stations on 29 April was identified in the data as well as in the simulated salinity distribution.

Phosphate and plankton dynamics during a drift experiment in the German Bight:simulation of phosphorus-related plankton production

“…Observations at 10 m depth supports the idea that the drifter moved into a different water body (Konig & Schrum 1997). Salinity showed the same 6-hourly variability as phosphate.…”

“…Thus, a possible explanation is that the drifting buoy moved back and forth during the sampled track time and moved into another water mass after 26 April. This assumption is supported by the results of Konig & Schrum (1997), who calculated the distance between the real position of the drift buoy and the position simulated by the model. From 25 to 27 April this distance reached its maximum.…”

“…One can see the interruption due to advection in many of the measurements during the drift experiment between 26 and 27 April (Konig & Schrum 1997, Raabe et al 1997.…”

Atmospheric input of lead into the German Bight - a high resolution measurement and model case study

“…Below, atmospheric concentrations and the atmospheric input are presented for the third drift period (April 23 to 30, 1991). Measurements and model results for other compartments of the ecosystem are given by Konig et al (1997), Moll (1997) and Raabe et al (1997) (all in this volume).…”

Surface drifters experiment in the south-eastern part of the Baltic Sea

“…The drifter experiments provide valuable data for the validation of the Lagrangian drift models that are widely used for estimating the fate of oil spills or for pointing out its potential sources (Liungman, Mattsson 2011;Loncar et al 2012). The Lagrangian drift models are also highly relevant for estimating the path of the drifting objects such as polluted water, living organisms or lost goods (Abbott 1990;König, Schrum 1997).…”