Introduction to special section on Recent Advances in the Study of Optical Variability in the Near-Surface and Upper Ocean

Optical variability occurs in the near-surface and upper ocean on very short time and space scales (e.g., milliseconds and millimeters and less) as well as greater scales. This variability is caused by solar, meteorological, and other physical forcing as well as biological and chemical processes that affect optical properties and their distributions, which in turn control the propagation of light across the air-sea interface and within the upper ocean. Recent developments in several technologies and modeling capabilities have enabled the investigation of a variety of fundamental and applied problems related to upper ocean physics, chemistry, and light propagation and utilization in the dynamic near-surface ocean. The purpose here is to provide background for and an introduction to a collection of papers devoted to new technologies and observational results as well as model simulations, which are facilitating new insights into optical variability and light propagation in the ocean as they are affected by changing atmospheric and oceanic conditions

Global yearly observation of different phytoplankton groups using PhytoDOAS on SCIAMACHY data: validation and first application.

Global information on the quantitative distribution of major functional phytoplankton types (PFTs) of the world ocean is important for understanding the marine phytoplanktons role in the global marine ecosystem. This study shows global biomass distributions from 2008 of different dominant PFTs analysed with PhytoDOAS, a method of Differential Optical Absorption Spectroscopy (DOAS) currently specialized for diatoms and cyanobacteria [1] from satellite data of SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) on ENVISAT. PhytoDOAS global maps of phytoplankton distribution are validated with collocated pigment water samples analyzed via HPLC. The global PFT satellite data sets are used as input data for and for validation of a biogeochemical model

PICOPHYTOPLANKTON DISTRIBUTION IN THE ATLANTIC GROUND-TRUTH FOR GLOBAL OBSERVATION OF PHYTOPLANKTON FUNCTIONAL GROUPS

Marine picophytoplankton, in particular cyanobacteria and prochlorophytes are ubiquitously distributed in the worlds oceans and are often especially in the more oligotrophic regions among the most important primary producers. The present work shows the results of in-situ measurements taken on meridional transects across the Atlantic Ocean. Data for phytoplankton pigment composition and particulate absorption give information about the functional groups found in the study area. Flow cytometry and an analysis of phycobilins were employed to encompass genera of prochlorophytes and cyanobacteria. These in situ measurements are used as ground-truth for the validation of hyper-spectral remote sensing data. High spectrally resolved satellite data from SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) on ENVISAT and GOME-2 (Global Ozone Measurement Experiment 2) on Meteosat are analysed with Differential Optical Absorption Spectroscopy (DOAS) and combined with the in situ data to improve determinations of phytoplankton functional groups distribution. http://www.sgmeet.com/aslo/nice2009/viewabstract2.asp?AbstractID=521

GLOBAL OBSERVATION OF DIFFERENT PHYTOPLANKTON GROUPS USING PHYTODOAS WITH SCIAMACHY AND GOME-2 DATA

In order to understand the marine phytoplanktons role in the global marine ecosystem, it is necessary to derive global information on the distribution of major functional phytoplankton types (PFT) in the world oceans. So far only the dominant PFTs can be analysed from ocean color sensors such as CZCS, SeaWiFS, MODIS or MERIS. In our study we use PhytoDOAS, a method of Differential Optical Absorption Spectroscopy (DOAS) specialized for phytoplankton, to retrieve the absorption spectra and concentrations of various phytoplankton groups from high spectrally resolved satellite data of SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) on ENVISAT and GOME-2 (Global Ozone Measurement Experiment 2) on Meteosat. In-situ measured phytoplankton absorption spectra were used to identify these characteristic absorption spectra in SCIAMACHY data in the range of 430-500 and 530-590 nm. Pigment concentrations of in situ measurements were used to validate the satellite data, which showed a good agreement with the collocated in-situ measurements and with the NASA Ocean Biogeochemical Model. Results are of great importance for global modelling of marine ecosystems and climate change studies. http://www.sgmeet.com/aslo/nice2009/viewabstract2.asp?AbstractID=541

Global quantitative observation of phytoplankton groups from space using PhyoDOAS on SCIAMACHY data

In order to understand the marine phytoplanktons role in the global marine ecosystem and on biogeochemical fluxes, it is necessary to derive simultaneously global information on the quantitative distribution of major phytoplankton functional groups of the world ocean. We show global biomass distributions from 2008 of diatoms and cyanobacteria analysed with PhytoDOAS, a method of Differential Optical Absorption Spectroscopy (DOAS) currently specialized for diatoms and cyanobacteria (Bracher et al. 2009) from satellite data of SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) on ENVISAT. In addition, first results from an extension of the PhytoDOAS method to simultaneous phytoplankton group fitting lead to global biomass distributions of other phytoplantkon types, such as coccolithophores, Phaeocystis sp., and dinoflagellates. These global maps of phytoplankton distribution are validated with collocated pigment water samples analyzed via HPLC and the calculated phytoplankton groups applying the CHEMTAX program (Mackey et al. 1996). The satellite based diatoms and cyanobacteria data sets are used as input data for global ecosystem and biogeochemical models. First applications of these approaches will be presented