Search results for: Johannes Pätsch

Items from 1 to 13 out of 13 results

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Variation that can be expected when using particle tracking models in connectivity studies

Marc Hufnagl, Mark Payne, Geneviève Lacroix, Loes J. Bolle, more

Journal of Sea Research > 2017 > 127 > C > 133-149

Hydrodynamic Ocean Circulation Models and Lagrangian particle tracking models are valuable tools e.g. in coastal ecology to identify the connectivity between offshore spawning and coastal nursery areas of commercially important fish, for risk assessment and more for defining or evaluating marine protected areas. Most studies are based on only one model and do not provide levels of uncertainty. Here...

article

An evaluation of the North Sea circulation in global and regional models relevant for ecosystem simulations

Johannes Pätsch, Hans Burchard, Christian Dieterich, Ulf Gräwe, more

Ocean Modelling > 2017 > 116 > C > 70-95

Simulations of the North Sea circulation by the global ocean model MPI-OM and the regional ocean models GETM, HAMSOM, NEMO, TRIM are compared against each other and with observational data for the period 1998–2009. The aim of the study is to evaluate the quality of the simulations in particular with respect to their suitability to drive biogeochemical shelf sea models. Our results demonstrate the...

article

The influence of winter convection on primary production: A parameterisation using a hydrostatic three-dimensional biogeochemical model

Fabian Große, Christian Lindemann, Johannes Pätsch, Jan O. Backhaus

Journal of Marine Systems > 2015 > 147 > C > 138-152

In the recent past observational and modelling studies have shown that the vertical displacement of water parcels, and therefore, phytoplankton particles in regions of deep-reaching convection plays a key role in late winter/early spring primary production. The underlying mechanism describes how convection cells capture living phytoplankton cells and recurrently expose them to sunlight.This study...

article

The North Sea — A shelf sea in the Anthropocene

Kay-Christian Emeis, Justus van Beusekom, Ulrich Callies, Ralf Ebinghaus, more

Journal of Marine Systems > 2015 > 141 > Complete > 18-33

Global and regional change clearly affects the structure and functioning of ecosystems in shelf seas. However, complex interactions within the shelf seas hinder the identification and unambiguous attribution of observed changes to drivers. These include variability in the climate system, in ocean dynamics, in biogeochemistry, and in shelf sea resource exploitation in the widest sense by societies...

article

Organic matter degradation in the German Bight/SE North Sea: Implications from stable nitrogen isotopes and amino acids

Alexandra Serna, Niko Lahajnar, Johannes Pätsch, Dierk Hebbeln, more

Marine Chemistry > 2014 > 166 > C > 103-113

Rising stable nitrogen isotope ratios (δ¹⁵N) in dated sediment records of the German Bight/SE North Sea track river-induced coastal eutrophication over the last 2 centuries. Fully exploiting their potential for reconstructions of pristine conditions and quantitative analysis of historical changes in the nitrogen cycle from these sediment records requires knowledge on processes that alter the isotopic...

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Interannual variability of carbon fluxes in the North Sea from 1970 to 2006 – Competing effects of abiotic and biotic drivers on the gas-exchange of CO2

Ina Lorkowski, Johannes Pätsch, Andreas Moll, Wilfried Kühn

Estuarine, Coastal and Shelf Science > 2012 > 100 > Complete > 38-57

The three-dimensional biogeochemical model ECOHAM was applied to the Northwest European Continental Shelf (NECS) (47° 41′ – 63° 53′ N, 15° 5′ W – 13° 55′ E) for the years 1970–2006. The development of annual carbon fluxes was analysed for the North Sea as the inner shelf region. We divided the North Sea into several regions, the northern North Sea, the southern North Sea, the German Bight and the...

article

Nitrogen and carbon cycling in the North Sea and exchange with the North Atlantic—A model study, Part II: Carbon budget and fluxes

Wilfried Kühn, Johannes Pätsch, Helmuth Thomas, Alberto V. Borges, more

Continental Shelf Research > 2010 > 30 > 16 > 1701-1716

The 3-d coupled physical–biogeochemical model ECOHAM (version 3) was applied to the Northwest-European Shelf (47°41′–63°53′N, 15°5′W–13°55′E) for the years 1993–1996. Carbon fluxes were calculated for the years 1995 and 1996 for the inner shelf region, the North Sea (511,725km ² ). This period was chosen because it corresponds to a shift from a very high winter-time North Atlantic Oscillation...

article

History of anthropogenic nitrogen input to the German Bight/SE North Sea as reflected by nitrogen isotopes in surface sediments, sediment cores and hindcast models

Alexandra Serna, Johannes Pätsch, Kirstin Dähnke, Martin G. Wiesner, more

Continental Shelf Research > 2010 > 30 > 15 > 1626-1638

The German Bight/SE North Sea is considered a hot-spot of river-induced eutrophication, but the scarce observational data of river nitrate loads prior to the 1970s complicate the assessment of target conditions for environmental management and legislation. Stable nitrogen isotope ratios (δ ¹⁵ N) in sediment records can be used to decipher historical river nitrate contributions. To better constrain...

article

Nitrogen cycling in the German Bight (SE North Sea) — Clues from modelling stable nitrogen isotopes

Johannes Pätsch, Alexandra Serna, Kirstin Dähnke, Tim Schlarbaum, more

Continental Shelf Research > 2010 > 30 > 2 > 203-213

Nitrogen isotope values (δ ¹⁵ N) of surface sediments in the German Bight of the North Sea exhibit a significant gradient from values of 5–6‰ of the open shelf sea to values above 11‰ in the German Bight. This signal has been attributed to high reactive N (N _r ) loading enriched in ¹⁵ N from rivers and the atmosphere. To better understand the processes that determine the intensity...

article

Mechanisms controlling the air–sea CO2 flux in the North Sea

A.E.F. Prowe, Helmuth Thomas, Johannes Pätsch, Wilfried Kühn, more

Continental Shelf Research > 2009 > 29 > 15 > 1801-1808

The mechanisms driving the air–sea exchange of carbon dioxide (CO2) in the North Sea are investigated using the three-dimensional coupled physical–biogeochemical model ECOHAM (ECOlogical-model, HAMburg). We validate our simulations using field data for the years 2001–2002 and identify the controls of the air–sea CO2 flux for two locations representative for the North Sea's biogeochemical provinces...

article

Nitrogen and carbon cycling in the North Sea and exchange with the North Atlantic—A model study. Part I. Nitrogen budget and fluxes

Johannes Pätsch, Wilfried Kühn

Continental Shelf Research > 2008 > 28 > 6 > 767-787

The three-dimensional biogeochemical model ECOHAM was applied to the Northwest European Shelf (47°41′–63°53′N, 15°5′W–13°55′E) for the years 1993–1996. Nitrogen budgets were calculated for the years 1995 and 1996 for the inner shelf region, the North Sea (511,725km ² ). Simulated temperatures as well as nitrate, oxygen, and chlorophyll concentrations are compared with observations.The mid-1990s...

article

Long-term simulation of the eutrophication of the North Sea: temporal development of nutrients, chlorophyll and primary production in comparison to observations

Johannes Pätsch, Günther Radach

Journal of Sea Research > 1997 > 38 > 3-4 > 275-310

The ecosystem model ERSEM II has been used to hindcast the development of the ecosystem of the North Sea during the years 1955 to 1993. The simulation was driven by the box-aggregated output from a general circulation model of the North Sea of corresponding duration; radiation, river inputs, atmospheric input and boundary conditions at the borders to the Atlantic Ocean and to the Baltic Sea were...

article

Climatological annual cycles of nutrients and chlorophyll in the North Sea

Günther Radach, Johannes Pätsch

Journal of Sea Research > 1997 > 38 > 3-4 > 231-248

A large amount of nutrient and chlorophyll data from the North Sea were compiled and organised in a research data base to produce annual cycles on a relatively fine spatial resolution of 1° in each horizontal direction. The data originate from many different sources and were partly provided by the ECOMOD data base of the Institut fur Meereskunde in Hamburg and partly by ICES in Copenhagen to cover...

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