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WIRED Magazine published a fantastic article explaining the importance of TROPICS and key science and societal benefit that TROPICS and the Pathfinder will be conducting once on orbit. The following is the link to the article by Meghan Herbst

Tiny Satellites Could Help Warn of the Next Big Hurricane

After being delayed over a year due to the pandemic, a NASA field campaign to study the role of small-scale whirlpools and ocean currents in climate change is taking flight and taking to the seas in May 2021.

Using scientific instruments aboard a self-propelled ocean glider and several airplanes, this first deployment of the Sub-Mesoscale Ocean Dynamics Experiment (S-MODE) mission will deploy its suite of water- and air-borne instruments to ensure that they work together to show what’s happening just below the ocean’s surface. The full-fledged field campaign will begin in October 2021, with the aircraft based out of NASA’s Ames Research Center in Mountain View, California.

“This campaign in May is largely to compare different ways of measuring ocean surface currents so that we can have confidence in those measurements when we get to the pilot in October,” said Tom Farrar, associate scientist at the Woods Hole Oceanographic Institution in Massachusetts and principal investigator for S-MODE.

The S-MODE team hopes to learn more about small-scale movements of ocean water such as eddies. These whirlpools span about 6.2 miles or ten kilometers, slowly moving ocean water in a swirling pattern. Scientists think that these eddies play an important role in moving heat from the surface to the ocean layers below, and vice versa. In addition, the eddies may play a role in the exchange of heat, gases and nutrients between the ocean and Earth’s atmosphere. Understanding these small-scale eddies will help scientists better understand how Earth’s oceans slow down global climate change.

Sub-mesoscale ocean dynamics, like eddies and small currents, are responsible for the swirling pattern of these phytoplankton blooms (shown in green and light blue) in the South Atlantic Ocean on Jan. 5, 2021.
Credits: NASA’s Goddard Space Flight Center Ocean Color, using data from the NOAA-20 satellite and the joint NASA-NOAA Suomi NPP satellite.

A Self-Powered Surfboard, for Science!

The team is using a self-propelled commercial Wave Glider decked out with scientific instruments that can study the ocean from its surface. The most important gadgets aboard are the acoustic Doppler current profilers, which use sonar to measure water speed and gather information about the how fast the currents and eddies are moving, and in which direction. The glider also carries instruments to measure wind speed, air temperature and humidity, water temperature and salinity, and light and infrared radiation from the Sun.

“The wave glider looks like a surfboard with a big venetian blind under it,” said Farrar.

That “venetian blind” is submerged under the water, moving up and down with the ocean’s waves to propel the glider forward at about one mile per hour. In this way, the wave glider will be deployed from La Jolla, California, collecting data as it travels over 62 miles (100 kilometers) out into the ocean offshore of Santa Catalina Island.
Decked out with solar panels and several scientific instruments, the wave glider will propel itself from Santa Catalina Island farther out to sea.

Laurent Grare of the Scripps Institution of Oceanography prepares to recover a Wave Glider during a pre-deployment test. Decked out with solar panels and several scientific instruments, the wave glider will propel itself from Santa Catalina Island farther out to sea.
Credits: Courtesy of Benjamin Greenwood / Woods Hole Oceanographic Institution

The new data will allow the scientists to estimate the exchange of heat and gases between Earth’s atmosphere and the ocean, and consequently better understand global climate change.

“We know the atmosphere is heating up. We know the winds are speeding up. But we don’t really understand where all that energy is going,” said Ernesto Rodriguez, research fellow at NASA’s Jet Propulsion Laboratory in Pasadena, California, and deputy principal investigator for the airborne parts of S-MODE. It’s likely that this energy is going into the ocean, but the details of how that process works are still unknown. The team thinks that small-scale eddies may help move heat from the atmosphere to the deeper layers of the ocean.
Eyes and Scientific Instruments in the Skies

While the Wave Glider continues its slow trek across the ocean’s surface, several airplanes will fly overhead to collect data from a different vantage.

“In an airplane, we can get a snapshot of a large area to see the context of how the bigger- and smaller-scale ocean movements interact,” said Rodriguez.

For example, a ship or wave glider travels slowly along a straight line, taking precise measurements of sea surface temperature at specific times and places. Airplanes move faster and can cover more ground, measuring the sea surface temperature of a large swath of ocean very quickly.

“It’s like taking an infrared image rather than using a thermometer,” explained Farrar.

A flight crew prepares for the B200 King Air Sub-Mesoscale Ocean Dynamics Experiment (S-MODE) at NASA’s Armstrong Flight Research Center in Edwards, California. From left to right are Jeroen Molemaker and Scott “Jelly” Howe.

Two planes will be used in the May test flights: a B200 plane from NASA’s Armstrong Flight Center in Edwards, California and a commercial plane from Twin Otter International. The B200 is carrying an instrument from NASA JPL called DopplerScatt to measure currents and winds near the ocean surface with radar. The Multiscale Observing System of the Ocean Surface (MOSES) instrument from the University of California, Los Angeles is also aboard to collect sea surface temperature data. On the Twin Otter plane is the Modular Aerial Sensing System (MASS) from the Scripps Institution of Oceanography at the University of California, San Diego, which is an instrument capable of measuring the height of waves on the surface of the ocean.

Delphine Hypolite, Multiscale Observing System of the Ocean Surface (MOSES) Operator from University of California Los Angeles, performs pre-flight checks on the MOSES Camera System at NASA’s Armstrong Flight Research Center in Edwards, California.

The fleet will gain a third member for the October experiments: NASA’s Langley Research Center Gulfstream III plane with JPL’s Portable Remote Imaging SpectroMeter (PRISM), an instrument to measure phytoplankton and other biological material in the water. The October deployments will also use a large ship and some autonomous sailing vessels, called Saildrones, in addition to planes and Wave Gliders.

After nearly a year and a half of delays due to the pandemic, the S-MODE team is excited to get their planes in the sky and the gliders in the water. “It was frustrating,” Rodriguez said, “but the science team hasn’t slowed down. The science keeps progressing.”

S-MODE is NASA’s ocean physics Earth Venture Suborbital-3 (EVS-3) mission, funded by the Earth System Science Pathfinder (ESSP) Program Office at NASA’s Langley Research Center in Hampton, Virginia, and managed by the Earth Science Project Office (ESPO) at Ames Research Center.

By Sofie Bates
NASA’s Earth Science News Team
Last Updated: May 19, 2021
Editor: Sofie Bates

Re-Posted from 0riginal Article

NASA researchers are using high resolution airborne data to determine the vulnerability and resilience of the Mississippi River Delta.

Cynthia Hall, NASA ESDS Program Community Coordinator

Many of the world’s large deltas are in peril due to coastal land subsidence and sea level rise. The Mississippi River Delta is one of these disappearing systems; it’s the world’s seventh largest delta and is a living laboratory where scientists can gather data to learn how to save these valuable ecosystems and the services they provide.

This series of false-color satellite images chronicles the growth of the Wax Lake Outlet Delta (upper feature) and the Atchafalaya River Delta (lower feature) in Louisiana between 1984 and 2017 where they empty into the Gulf of Mexico. All of the images were acquired by instruments aboard the joint NASA/USGS Landsat series of satellites. Credit: NASA Earth Observatory.

On average there is one delta for every 300 km of shoreline around the world. As rivers meet the ocean, slowing down and fanning out, sediments are dropped, forming a delta. Coastal waves, river discharge, vegetation, and tidal water flow all influence the development of deltas. Coastal communities rely on deltaic environments for many reasons and their disappearance can have catastrophic effects. Deltas serve as a buffer for storm surges, thereby protecting mainland areas; they serve as nurseries for a variety of marine organisms; they sustain and provide sustenance for biologically diverse ecosystems; and their soil serves as a filter that removes toxins from the water. The loss of a delta to subsidence and sea level rise would result in numerous environmental, economic, and social impacts on coastal communities.

The Mississippi River Delta is a unique testbed in that it is sinking in some areas, like the Terrebonne Basin, but growing in adjacent areas, like the Atchafalaya Basin to the west. The Terrebonne Basin is engineered (marked by channelization and levees), and this has decreased sediment flow to the delta floodplain. Large parts of the Atchafalaya Basin, conversely, allow rivers to deliver sediment to that basin. According to Delta-X principal investigator (PI) Dr. Marc Simard and co-PI Dr. Cathleen Jones at NASA’s Jet Propulsion Laboratory in Pasadena, CA, the Mississippi River Delta offers the unique opportunity to investigate areas with similar vegetation and climate, but very different soil accretion patterns. Understanding delta formation in an environment like the Mississippi River Delta, that is experiencing both erosion and accretion, is important because the U.S. Gulf Coast is experiencing some of the highest levels of global sea level rise: between 9 to 12 mm per year, which is three-to-four times the global average.

The Investigation

NASA’s Delta-X airborne mission, with flights that began on March 26, 2021, is gathering remotely sensed and in situ data to study changes occurring to the water, vegetation, and sediment along the Atchafalaya and Terrebonne Basins. The data will be assimilated into a model to forecast the resilience and vulnerability of the delta given the rising seas; the framework for the model can be used for forecasting change in other delta systems around the world. Delta-X was competitively selected through NASA’s Earth Venture Suborbital-3 program.

Delta-X uses three primary airborne sensors: the Airborne Visible-Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG), an instrument with high spectral resolution at visible wavelengths; the Air Surface Water and Ocean Topography (AirSWOT) instrument suite, which includes a Ka-band synthetic aperture radar (SAR); and the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), which collects data in the L-band. Wavelength is an important feature to consider when working with SAR since the wavelength determines how the radar signal interacts with the surface and how far the signal penetrates into a medium. The Ka-band represents a shorter wavelength and is able to measure highly reflective rough water surfaces with little to no vegetation, whereas the longer wavelength L-band can penetrate more heavily vegetated areas to measure changes in the water surface below vegetation.

For more information on sensors and spectral resolution, see the Earthdata Backgrounders What is Remote Sensing and What is Synthetic Aperture Radar.

These airborne instruments collect data more frequently than satellites in order to detect changes to water levels and sediment concentration over a full tidal cycle (the Gulf Coast experiences diurnal tides, meaning one high and one low tide per day). The data will be collected concurrently on three different aircraft, while scientists in the field collect in situ data at the same time. This facilitates multi-scale and multi-instrument calibration of models. These models will be used to validate upcoming satellite missions like the Surface Water and Ocean Topography (SWOT) and the NASA/Indian Space Research Organization (ISRO) Synthetic Aperture Radar (NISAR) missions. These missions will not have the ability to make multiple measurements during a single tidal cycle, however. SWOT will obtain measurements over a given area every 21 days and NISAR every 12 days.

Delta-X makes breakthrough advances in the study of deltaic evolution, moving beyond coarse areal averaging to resolve mesoscale features. Click on image for larger view. Credit: NASA’s Jet Propulsion Laboratory.

The data from Delta-X will be used to calibrate and validate a series of dynamic, hydroecological models, which can then be used to forecast the future of the Mississippi River Delta. Delta formation models before AirSWOT were developed at a coarse scale. Delta-X co-PI Jones equates this to a bathtub view, in which you are looking at the entire deltaic system (macroscale). To more accurately predict the resilience of the delta and inform realistic remediation plans, measurements at a smaller, or mesoscale (around one hectare [10,000 m2] or roughly the size of a sports field), are needed. To make better predictions about delta formation, scientists need to be able to define channels, surface water levels and discharge, sediment movement, and plant production at a much finer resolution than coarse areal averages.

The UAVSAR data will create maps of water level changes in wetlands over time; AirSWOT data will provide water surface elevation measurements over the same time period, but within channels and lakes. These measurements help with understanding river discharge and sediment transport across the floodplain’s wetlands. There are two processes which contribute to soil accretion: delivery of sediments and plant production of organic material (i.e. roots and litter). AVIRIS-NG will be used to estimate the quantity of sediment being transported in the rivers and also to estimate plant structure, including species, biomass, and spatial distribution. This information will be incorporated into a model that simulates how the delta evolves.

Left image: Vegetation classification of the Atchafalaya Basin, LA, using data acquired from the AVIRIS-NG sensor, 2016. Credit: Jensen, D.J., Simard, M., Twilley, R., Castaneda, E. & McCall, A. 2020. NASA’s ORNL DAAC (DOI: 10.3334/ORNLDAAC/1821). Right image: Map of water level changes based on water surface elevations measured by UAVSAR on October 16, 2016, at 14:08 and 16:37 UTC. Credit: Jones, C., Simard, M. & Lou, Y. 2020. NASA’s ORNL DAAC (DOI: 10.3334/ORNLDAAC/1823).

All of these variables help scientists better understand the processes contributing to soil accretion, which is what is needed to save these critical geomorphic systems. Changing variables within the model will provide scientists with insight as to how the delta will respond under different circumstances.

The models based on Delta-X data, once developed and calibrated, determine how much sediment will need to be put back into the system sustainably, that is, in the most natural way possible, to mitigate the impacts of a rising sea. Jones notes, “…deltas are really sensitive. They live in this balance between losing and gaining land. But if we understand all the processes developed over millennia that have kept them in balance, we will be able to reverse some of the [loss].” The Delta-X modeling framework can be used for forecasting change in other delta systems around the world by using its remote sensing and numerical model parameters.

The Application

Model output showing particle flow from the Wax Lake Delta. Developed through a Python package from Hariharan, J., Wright, K. & Passalacqua, P. (2020). “dorado: A Python package for simulating passive particle transport in shallow-water flows.” Journal of Open Source Software, 5(54): 2585 [DOI: 10.21105/joss]. Credit: NASA’s Jet Propulsion Laboratory.

The state of Louisiana has a $50 billion, 50-year plan to protect its coastline from erosion and rising sea levels. Data from Delta-X could help better inform coastal restoration efforts and sediment diversions.

According to Delta-X co-PI Simard, “In terms of application, Delta-X is very important; there is a science component of course, but application-wise we are really hoping it’s going to support decision making . . . to inform the state [of Louisiana] about remediation plans.” In fact, the Delta-X team has been interfacing with Louisiana’s Coastal Protection and Restoration Authority and the non-profit Water Institute of the Gulf in Baton Rouge to help develop sustainable coastal restoration efforts. In addition, 12 co-investigators from eight institutions, along with undergraduate, graduate, and postdoctoral students, have been involved in mission planning and will be working tirelessly in the coming months to understand this fragile ecosystem.

While the data and models from Delta-X are specifically for the Mississippi River Delta, Simard notes that, “the framework can be applied [to other deltas]. We can either take the model parameter values obtained during Delta-X to implement models elsewhere or, even better, we can have another Delta-X campaign over those other deltas to do a better job there too.”
Data Availability

To demonstrate the viability of the mission, two pre-Delta-X missions were conducted in 2015 and 2016. The data from these campaigns are archived at NASA’s Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) and can be accessed at the links below:

Pre-Delta-X data in Earthdata Search
Pre-Delta-X data at ORNL DAAC

Delta-X data are expected to be available through Earthdata Search and ORNL DAAC in the fall of 2022. To keep up to date on the Delta-X campaign, read the Delta-X Science Blog.

Original Article Published April 12, 2021