Improvement of MERIS level 2 products in Baltic Sea coastal areas by applying the Improved Contrast between Ocean and Land processor (ICOL) - data analysis and validation
Improvement of MERIS level 2 products in Baltic Sea coastal areas by applying the Improved Contrast between Ocean and Land processor (ICOL) - data analysis and validation
In this paper we compare the following MERIS processors against sea-truthing
data: the standard MERIS processor (MEGS 7.4.1), the Case 2 Regional processor
(C2R) of the German Institute for Coastal Research (GKSS), and the Case 2Water
Properties processor developed at the Freie Universit¨at Berlin (FUB). Furthermore,
the Improved Contrast between Ocean and Land processor (ICOL), a prototype
processor for the correction of adjacency effects from land, was tested on all three
processors, and the retrieval of level 2 data was evaluated against sea-truthing data
before and after ICOL processing.
The results show that by using ICOL the retrieval of spectral reflectance in
the open sea was improved for all processors. After ICOL processing, the FUB showed rather small errors in the blue, but underestimated in the red −34%
Mean Normalised Bias (MNB) and 37% Root Mean Square (RMS). For MEGS the
reflectance in the red was underestimated by about −20% MNB and 23% RMS,
whereas the reflectance in the other channels was well predicted, even without any
ICOL processing. The C2R underestimated the red with about −27% MNB and
29% RMS and at 412 nm it overestimated the reflectance with about 23% MNB and
29% RMS. At the outer open sea stations ICOL processing did not have a strong
effect: the effect of the processor diminishes progressively up to 30 km from land.
At the open sea stations the ICOL processor improved chlorophyll retrieval
using MEGS from −74% to about 34% MNB, and TSM retrieval from −63% to
about 22% MNB. Using FUB in combination with ICOL gave even better results
for both chlorophyll (25% MNB and 45% RMS) and TSM (−4% MNB and 36%
RMS) in the open Baltic Sea. All three processors predicted TSM rather well, but
the standard processor gave the best results (−12% MNB and 17% RMS). The
C2R had a very low MNB for TSM (1%), but a rather high RMS (54%). The FUB
was intermediate with −16% MNB and 31% RMS.
In coastal waters, the spectral diffuse attenuation coefficient Kd(490) was well
predicted using FUB or MEGS in combination with ICOL (MNB about 12% for
FUB and 0.4% for MEGS). Chlorophyll was rather well predicted in the open
Baltic Sea using FUB with ICOL (MNB 25%) and even without ICOL processing
(MNB about 15%). ICOL-processed MEGS data also gave rather good retrieval
of chlorophyll in the coastal areas (MNB of 19% and RMS of 28%). In the open
Baltic Sea chlorophyll retrieval gave a MNB of 34% and RMS of 70%, which may
be due to the considerable patchiness caused by cyanobacterial blooms.
The results presented here indicate that with the MERIS mission, ESA and co-
workers are in the process of solving some of the main issues regarding the remote
sensing of coastal waters: spatial resolution; land-water adjacency effects; improved
level 2 product retrieval in the Baltic Sea, i.e. the retrieval of spectral reflectance
and of the water quality products TSM and chlorophyll.
Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies
Informacja
SZANOWNI CZYTELNICY!
UPRZEJMIE INFORMUJEMY, ŻE BIBLIOTEKA FUNKCJONUJE W NASTĘPUJĄCYCH GODZINACH:
Wypożyczalnia i Czytelnia Główna: poniedziałek – piątek od 9.00 do 19.00