Mannino, Antonio: NASA GSFC (Project Lead)
Project Funding:
2014 - 2017
NRA: 2013 NASA: Terra and Aqua: Algorithms--Existing Data Products
Funded by NASA
Abstract:
Important Earth Observation System objectives are to quantify Chlorophyll a (Chla) in marine environments, know the measurement uncertainty and ensure data are valid over the long-term. Chla is one of the standard MODIS products produced by NASA Ocean Biology Processing Group. Most satellite missions require on-orbit accuracy to within 35%. For remote sensing validation of Chla, HPLC is the reference method. Assuming total uncertainty is split evenly between satellite and field components, the HPLC accuracy for Chla must be within 25%, but accuracy within 15% (presumably) offers opportunities to improve remote sensing algorithms. Intercalibrations among laboratories (primarily the SeaHARRE (SeaWiFS HPLC Analysis Round-Robin Experiment) activities) that measure marine pigments have demonstrated that average accuracy for Total Chla to within 6-7% is possible, for laboratories that follow a quality assurance (QA) process. For other pigments, average accuracy to within 25% is possible; in many instances accuracy can be improved to 15% if methods are quality-assured.
An important result of the SeaHARRE HPLC intercomparisons was the identification of performance criteria that allow a determination of whether a method is capable of achieving specific accuracy requirements. The GSFC Field Support Group (FSG) maintains a detailed QA plan to ensure compliance with these performance metrics established during SeaHARRE activities and consistent results in between such activities. A QA plan includes repetitive quality control measurements and routine assessment to ensure these measurements fall within quantified limits, for in the absence of such rigor, it is not possible to know whether the above-described accuracy requirements set for researchers is being achieved.
GSFC's FSG proposes to provide quantitative concentration results for up to 3000 samples collected by Ocean Biology and Biogeochemistry (OBB) investigators under certain NASA grants for 12 primary pigments (including their secondary components) and selected tertiary pigments, as defined in SeaHARRE intercalibration activities, plus relevant pigment sums and ratios. Reported results will also include information about the limit of quantitation (LOQ) and measures of analysis precision at the time of data collection. This activity would provide the necessary field measurements of HPLC- derived Chla for NASA PIs to support validation and continued maintenance of the MODIS Chla algorithm.
GSFC FSG chromatographers have consistently produced state-of-the-art pigment results, as evidenced by performance during inter-laboratory comparisons (averaging 5.2% for TChla and 11.7% for other pigments). The FSG maintains strict adherence to a HPLC QA plan, and personnel offer sixteen years of experience providing quantitative pigment analyses to multiple clients, and fourteen years of experience researching method improvements, specifically as they relate to improving accuracy and precision of results.
More details may be found in the following project profile(s):
