NOMAD: NASA bio-Optical Marine Algorithm Dataset
NOMAD is a publicly available, global, high quality in situ bio-optical data set for use in ocean color algorithm development and satellite data product validation activities. Data products include coincident observations of water-leaving radiances and chlorophyll a concentrations, along with relevant metadata, such as the date, time, and coordinates of data collection and binary processing flags. Inherent optical properties (IOPs; e.g., spectral absorption and backscattering coefficients) and aerosol optical thicknesses have been or will be included in the near future. The entire dataset is available via a digital text file provided below under Downloads. Additional background details, such as the motivation for creating such a data set, and a historical perspective of such data sets, are provided in the Werdell and Bailey reference listed below.
NOMAD is available for research uses only. It was compiled by the NASA Ocean Biology Processing Group at Goddard Space Flight Center, Maryland, USA, using generous data contributions from the ocean color research community. Source bio-optical data are available online via a suite of SeaBASS Search Engines. Optimum interpolation (OI) sea surface temperature (SST) data were acquired from the NOAA Climate Diagnostics Center. ETOPO2 water depths were acquired from the NOAA National Geophysical Data Center. NOMAD Data access and use are governed by the SeaBASS Data Access Policy. Please direct comments, questions, and identified outliers to the SeaBASS Administrator.
How to Use SeaBASS
Standardized Fields and Units
Below is a table of the standard field names and associated units for use in submitting data to the SeaBASS bio-optical archive. The field names are not case sensitive. Use the search bar or the find function in your browser to search the table for words or patterns found in the field names, units or descriptions. Please contact SeaBASS staff if you want to discuss adding new fields.
Special notes regarding wavelength-specific measurements: There are two different ways to indicate wavelengths (nm) in a SeaBASS file. If metadata such as date, location, or depth vary within the data, then append the wavelength number to the field name for every measurement combination. For example, downwelling irradiance ('Ed') measured at 412.3 nm is 'Ed412.3' (listed as separate columns alongside other Ed measurements, like Ed416.2, Ed419, etc.) Alternately, if date, location, and depth are assumed to be approximately constant for all measurements in the file, then use the field 'wavelength' to provide a column of the measured wavelengths and don't include them as part of the field names (this pivoted layout is commonly used for reporting spectrophotometric measurements or other measurements that use the data_type=scan keyword).
Two additional tables are provided below (Field Name Suffixes & Modifiers). The reusable naming conventions in those tables are used to create new field names without having to add dozens or hundreds of variations to the Table of Field Names and Units. For example, "_sd" (for standard deviation) appears in the table of suffixes and may be appended to any existing SeaBASS field name (e.g., "chl_sd" or "Rrs510_sd".) Similarly, field-specific names can be created ad infinitum using _bincount (i.e., number of averaged samples), and _quality. The table of modifiers allows extra information to be part of field names, typically to indicate versions of measurements that are either more specific or modified. For example, modifiers are used to denote size-fractionated measurements (see _#umfilt and _#umprefilt), specific excitation or emission wavelengths, or polarized measurements. Field names may be constructing by combing entries from multiple tables, with any applicable wavelength first, followed by "Modifiers", followed by a "Suffix".
Data Access Policy and Citation
NASA's Earth Science program was established to use the advanced technology of NASA to understand and protect our home planet by using our view from space to study the Earth system and improve prediction of Earth system change. To meet this challenge, NASA promotes the full and open sharing of all data with the research and applications communities, private industry, academia, and the general public. The greater the availability of the data, the more quickly and effectively the user communities can utilize the information to address basic Earth science questions and provide the basis for developing innovative practical applications to benefit the general public. In this regard, all users incorporating SeaBASS data into their research are expected to acknowledge both their data sources (the original data contributors and SeaBASS) and NASA, and to abide by the Access Policy.
Who We Are
Frequently Asked Questions
This page provides general SeaBASS documentation and guidelines, focusing primarily on how submissions should incorporate free-form information in external documents. SeaBASS submissions have two general types of metadata, 1) self-contained metadata, e.g., machine-readable metadata headers, and text comments and 2) external documents and calibration files. Note that these sorts of files are not expected to be in SeaBASS file format and thus don't get scanned with FCHECK.
1) Self-contained information within SeaBASS Data Files
- /documents (REQUIRED, a comma-separated list of the file name(s) of all external documentation)
- /calibration_files (REQUIRED, a comma-separated list of the file name(s) of all of external calibration files)
- Comments (OPTIONAL, free-form text information may be included in the header. Comment lines must start with an exclamation point. e.g., ! This is a comment. Comments are the only headers allowed to contain whitespace)
2) External Documents and Calibration Files (bundled together in a folder called "documents" for every cruise)
- Submitted documents should include written report(s) documenting all your methods
- Explain all methods, including those related to deployment, sampling, and analysis. Important instrument settings and calibration information must also be retained for traceability. Standalone documentation should be organized into a "documents" directory that is part of your submission. In your data files, reference the relevant external files via the "/documents" metadata headers
- Remember to list the names of these files in the /documents header
What file formats are preferred?
Plain text (.txt) or PDF (.pdf)
- Documents must also include Data Submission Special Requirements (mandatory checklists for certain types of submissions that need to be added to your submitted documents)
- Consult the Data Submission Special Requirements page to see if it includes special guidelines for the types of measurements you wish to submit. The page includes required checklists, required special metadata headers, and example data files. Check back periodically, as new content is added to that page over time to include additional data types and other updates
These checklists are new to the community as of early 2020. The SeaBASS team welcomes feedback if you have suggestions for improving specific forms, and is interested to hear if you have requests for additional information or topics
- Remember to list the names of these files in the /documents header
- Calibration files (if applicable) should be organized and submitted within the "documents" directory (organize subfolder(s) as needed)
- Remember to list all these file names in the /calibration_files header
- What file formats are allowed?
- Calibration files and other special files should usually be uploaded in their native format