University of Twente Student Theses
Quantification of primary production in Wadden Sea using remote sensing and field measurements
Woldegiorgis, Micael G. (2012) Quantification of primary production in Wadden Sea using remote sensing and field measurements.
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| Abstract: | Primary production is production of organic compounds by the processes of photosynthesis through interaction of carbon dioxide from the atmosphere or aquatic system, inorganic raw materials and light as a main energy source. Aim of the research was to use a remote sensing approach to quantify phytoplankton biomass and its primary production in the water column of the Wadden Sea and compare them with insitu data. Long-term remote sensing data were utilized to analyze the Primary Productivity of Wadden Sea with its trends and anomalies. In this work we determined the temporal–spatial variations of primary production (PP), based on a vertically generalized production model (VGPM) from 2003 to 2011 using two sensors- MERIS and MODIS. The result showed that higher Chl-a concentration and PP values were recorded in Wadden Sea in 2003 and 2007 than in other years. Between 2003-2011, the annual mean daily PP, calculated as the mean for all 3 sites (near Marsdiep, mid of Dutch Wadden Sea and near west Terschelling), ranged from 0.026 to 4.52 g C m-2day-1. The highest daily PP of Wadden Sea was occurred in 2003 and 2008, 4.52 and 4.40 gC m-2day-1. A mean value of the daily mean PP for 3 sites provides an approximation of annual PP for Wadden sea values, calculated by sum up every month to give total annual PP. The total annual integrated PP of the Wadden sea , from 2003-2010, ranged from 22.95 gC m-2 year-1 in 2010 to 24.96 gC m-2 year-1 2003. From MODIS time series analyzed data, mean daily PP decreased significantly in 2009-2011 compared with 2003-2008. From the available 2011 MERIS images of study area annual mean PP is 2.50 g C m-2 day-1 and RMSE 0.19 g C m-2 day--1. There were marked spatial differences in PP within Wadden Sea. The highest annual mean daily PP of 4.52 gC m-2day-1 was recorded at site near Marsdiep inlet and has relatively higher PP than mid and eastern part of Dutch Wadden Sea. Monthly variations of daily mean PP were characterized by lowest values in January (following the Chl-a concentration) and peaks in July in all sites and sometimes highest PP occur in June. The summer (June– August) algal bloom accounted for 49.0% of the annual PP in Wadden Sea. By considering the effect of water temperature, photosynthetically active radiation and photoperiod on PP, the VGPM- generated PP more accurately captured monthly variations in Wadden Sea. Though the VGPM model has overestimated the insitu data, PP derived using the model from remote sensing approaches was strongly correlated with the 14C-based PP estimates of insitu measurements. The performance of the VGPM model can be improved further by adjusting retrieval models on important parameters such as Chl-a concentration (chl-a), euphotic depth (Zeu) and maximum Carbon fixation rate in water column (PBopt). |
| Item Type: | Essay (Master) |
| Faculty: | ITC: Faculty of Geo-information Science and Earth Observation |
| Programme: | Geoinformation Science and Earth Observation MSc (75014) |
| Link to this item: | https://purl.utwente.nl/essays/93714 |
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