PO.DAAC

Oceans Melting Greenland (OMG) is a NASA Earth Venture Suborbital (EVS-2) mission that aims to improve estimates of sea level rise by addressing the question: To what extent are the oceans melting Greenland’s ice from below? OMG observes changing water temperatures on the continental shelf surrounding Greenland, and how marine glaciers react to the presence of warm, salty Atlantic Water. The complicated geometry of the sea floor steers currents on the shelf and often determines whether Atlantic Water can reach into the long narrow fjords and interact with the coastal glaciers. Because knowledge of these pathways is a critical component of understanding the interaction between the oceans and ice sheet, OMG facilitates improved measurements of the shape and depth of the sea floor in key regions.

OMG uses airborne, in situ, and ship-based observations to provide a revolutionary dataset for understanding ocean/ice interactions to improve estimates of global sea level rise. Please see the OMG website and PO.DAAC’s OMG mission webpage for more information on the OMG mission.

OMG mission datasets are archived and distributed by the PO.DAAC. At this time, the PO.DAAC is pleased to announce the public release of the Oceans Melting Greenland (OMG) Airborne eXpendable Conductivity Temperature Depth (AXCTD) Version 1 dataset. The dataset is described and discoverable via the PO.DAAC dataset information page. The dataset information pages also provide access to the technical documentation and guidance on how to cite the data.

Figure 1. The left shows an AXCTD being deployed from a plane. The right shows the locations of AXCTD drops for a single field campaign around Greenland.

The new RSS SMAP Version 4.0 data spans the full mission, from 2 April 2015 to the present.  Enhancement with this version include: 1) an improved land correction allowing retrievals closer to the coast (30-40km), 2) implementation of an improved sea-ice mask based on AMSR2, revised solar flagging, and inclusion of SSS uncertainty fields in the Level 3 (L3) products. Global coverage L3 data products include an 8-day running mean as well as monthly averages. Level 2 swath data are also available as part of the product release. They are available with a latency of 3 days for the Level 2 dataset, and 8 days and 1 month for the respective L3 products. The spatial resolution of the SMAP sensor and improved land correction with this V4.0 release allows for improved applications to coastal and regional studies.  The image shows global maps of SSS (left panel) and associated uncertainties (right) on 27 March 2015 from the V4.0 L3 8-day running mean product.

The RSS SMAP SSS V4.0 datasets are described, discoverable, and accessible via the PO.DAAC data portal, as are the associated technical documentation.

The Cyclone Global Navigation Satellite System (CYGNSS), launched on 15 December 2016, is a NASA Earth System Science Pathfinder Mission that is designed to collect the first frequent space-based measurements of surface wind speeds in the inner core of tropical cyclones. Made up of a constellation of eight micro-satellites, the CYGNSS observatories provide nearly gap-free Earth coverage with a mean (i.e., average) revisit time of seven hours and a median revisit time of three hours. Primarily intended to be an ocean surface wind speed measuring mission, CYGNSS has been measuring science-quality ocean surface wind speed data since the beginning of the observation record on 18 March 2017. Following multiple years of data collection, CYGNSS has proven capable of estimating ocean surface measurements beyond wind speed. The PO.DAAC has just released the first version of the Level 2 Ocean Surface Heat Flux Science Data Record. This dataset was provided courtesy of CYGNSS Science Team investigators Derek Posselt (PI, JPL) and Juan Crespo (Co-I, JPL), and delivers time-tagged and geolocated ocean surface heat flux parameters in daily netCDF-4 formatted files with 25x25 kilometer footprint resolution from the Delay Doppler Mapping Instrument (DDMI) aboard the CYGNSS satellite constellation.

Animation of the ocean surface heat flux (top: latent heat; bottom: sensible heat) over the period 18 March 2017 to 30 June 2019 from the CYGNSS Level 2 Ocean Surface Heat Flux Science Data Record Version 1.0

The Coupled Ocean-Atmosphere Response Experiment (COARE) algorithm is used in this dataset to estimate the latent and sensible heat fluxes and their respective transfer coefficients. While COARE's initial intentions were for low to moderate wind speeds, the version used for this product, COARE 3.5, has been verified with direct in situ flux measurements for wind speeds up to 25 m/s. As CYGNSS does not provide air/sea temperature, humidity, surface pressure or density, the producer of this dataset obtains these values from the NASA Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2), which uses data assimilation to combine all available in situ and satellite observation data with an initial estimate of the atmospheric state, provided by a global atmospheric model. Since the MERRA-2 is updated on a monthly interval, this heat flux dataset is released in monthly increments.

Access to the data, as well as a complete listing of documentation resources, read software, and access information, is available here: https://podaac.jpl.nasa.gov/dataset/CYGNSS_L2_SURFACE_FLUX_V1.0.

More detailed dataset information can be found in the dataset user guide, with specific variable descriptions available in an Excel-formatted data dictionary.