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Earth Matters

Highlights from The Earth Observer

November 7th, 2018 by Adam Voiland

A new edition of The Earth Observer, a bi-monthly publication that covers the nuts-and-bolts of NASA’s Earth Observing System, is out. Here are a few excerpts, along with some musical headlines that may get you humming as you read. You can download the full issue here. Back issues here.

ICE ICE BABY
The Advanced Topographic Laser Altimeter System (ATLAS), the lone instrument on ICESat-2, successfully fired its laser on September 30 after the mission operations team completed testing of the spacecraft and opened the door protecting the optics. The primary science mission for ICESat-2 is to gather enough observations to estimate the annual height change of the Greenland and Antarctic ice sheets to within four millimeters. Hundreds of billions of tons of land ice melt into the ocean annually, raising sea levels worldwide. In recent years, meltwater from Greenland and Antarctica alone has raised global sea level by more than a millimeter a year, and the rate is increasing.

THIS LANDSAT IS YOUR LANDSAT
In January 2008, the U.S. Geological Survey and NASA decided to open the full Landsat image archive for public access on a non discriminatory, no-cost basis. This change in Landsat’s data policy ushered in a new era of Landsat data uses and applications while also revolutionizing the way Landsat has been woven into scientific discovery, economic prosperity, and public policy for management of land and water resources across a range of scales.

DEVELOPING SATELLITE SKILLS FOR 525,600 MINUTES (TIMES TWENTY)
From 1998 to the current 2018 fall term, the NASA DEVELOP National Program has engaged 4,671 participants who have conducted 931 projects. The program bridges the gap between science and society by demonstrating how NASA Earth Science data can be applied to environmental decision making. These projects have demonstrated the applications of NASA Earth observations to a wide variety of sectors, addressing topics such as drought monitoring, vector-borne disease risk, water-quality assessments, pre- and post-wildfire mapping, agriculture monitoring, and critical habitat identification.

I CAN SEE CLEARLY NOW

The first Earth Science Decadal Survey identified CLARREO as a Tier-1 (i.e., highest) priority mission for development. The CLARREO Pre-Formulation Mission, referred to herein as the “Full” CLARREO mission, was recommended to better understand climate change. The foundation of CLARREO is the ability to produce highly accurate climate records to test climate projections in order to improve models and enable sound policy decisions.

A Boatload of Scientists Head Out to Sea

August 10th, 2018 by Adam Voiland

A boatload of scientists headed out to sea this week. Actually, two boatloads. Both the R/V Salley Ride and the R/V Roger Revelle are taking part in a mission called Export Processes in the Ocean from Remote Sensing (EXPORTS).

Their plan: track what happens to carbon as it sinks from the well-lit surface of the ocean down to the dimmer “twilight zone” (between 650 feet and 3300 feet below the surface) using floats, gliders, and other scientific equipment. Then they’ll try to do the same thing using satellites.

To help spread the word about the scientific work the team will be doing, oceanographer and blogger Kim Martini put together a fun set of #sciencetradingcards that people have been passing around on social media. Maybe she’ll roll out phytoplankton and zooplankton trading cards next?

Read more about the project from the mission website, a NASA Goddard press release, and the videos below. See a sample of the trading cards at the bottom of the page.

 


Project Title: Linking sinking particle chemistry and biology with changes in the magnitude and efficiency of carbon export into the deep ocean Project Lead: Margaret Estapa, Skidmore College

 


Project Title: Autonomous Investigation of Export Pathways from Hours to Seasons
Project Lead: Craig Lee – University of Washington

 


Ivona Cetinic – EXPORTS Project Scientist
NASA Goddard Space Flight Center/USRA

 


Project Title: Diatoms, Food Webs and Carbon Export – Leveraging NASA EXPORTS to Test the Role of Diatom Physiology in the Biological Carbon Pump Project Lead: Bethany Jenkins, The University of Rhode Island

 


Project Title: In Situ Optics and Biogeochemistry in Support of EXPORTS Science Project Lead: Antonio Mannino, NASA Goddard Space Flight Center

 


Project Title: Zooplankton-Mediated Export Pathways: Quantifying Fecal Pellet Export and Active Transport by Diel and Ontogenetic Vertical Migration in the North Pacific Project Lead: Deborah Steinberg, Virginia Institute of Marine Science

For more than two months, lava has been pouring from part of Hawaii’s Kilauea volcano, destroying homes and remaking the land surface. More data and imagery of the eruption is flowing in from satellites, drones, and ground-based sensors than Earth Observatory can cover, but here are a few striking images that we would be remiss not to share.

By The Lava’s Early Light
NASA Astronaut Ricky Arnold tweeted this nighttime photograph of lava on June 20, 2018. If the Star Spangled Banner had been composed in Hawaii rather than Baltimore, maybe “lava’s early light” would have made it into the lyrics. Credit: NASA


The Wrong Side of the Lava Flow


Notice the stark differences in landscapes on the northern and southern sides of the lava channel. With trade winds blowing heat and volcanic gases to the southwest, the north side remained green. Vegetation on the south side, yellowed and brown, took a battering. This aerial photograph was taken on July 10, 2018. Image Credit: USGS.


A Colorful Satellite Perspective on a Collapsing Caldera

As lava flows from some parts of Kilauea, other parts of the volcano have been sinking. In the case of the summit caldera, the rate of subsidence has been dramatic. This interferometric synthetic aperature radar (InSAR) image, or interferogram, shows surface movement at the summit caldera between June 9 and June 23. Each cycle of yellow-blue-purple indicates approximately 5 inches (13 centimeters) of movement. Areas where the colorful lines are the closest have shifted the most. The data was collected by Advanced Land Observing Satellite-2 (ALOS-2), a Japanese Aerospace Exploration Agency (JAXA) mission. Read more about this image and type of data from NASA’s Disasters Program. Image Credit: NASA/JAXA.

The Same Caldera Collapse Seen from the Ground


This sequence of images shows rapid subsidence of the caldera floor, along with the development of scarps. One photograph is shown per day between June 13 and 24. The photos were taken from the southern caldera rim, near Keanakāko‘i Crater, and face north. Image Credit: USGS.


Laze Billows into the Air as Lava Pours into the Sea


In this Sentinel-2 image,  a large plume of laze—steam, volcanic gases, and shards of glass—blows west over Hawaii as lava poured into the sea on June 27, 2018. Pierre Markuse created this image using data from Sentinel-2, a satellite managed by the European Space Agency. He regularly downloads and processes Sentinel and Landsat satellite data and has posted dozens of Kilauea images on Flickr. Image Credit: ESA/Sentinel-2/Markuse

The Sounds of Satellites

June 28th, 2018 by Adam Voiland

Orbit Pavilion. Image courtesy of NASA/Jet Propulsion Laboratory-Caltech/The Studio/Dan Goods

Sure, space may be silent, or at least absent the sound waves that human ears can hear. But put that aside for a moment, and try to imagine the sound of a satellite orbiting hundreds of miles above Earth’s surface.

Now imagine 19 sounds for 19 Earth-observing satellites — the murmur of ocean waves for a spacecraft that studies the oceans, or the howl of winds for one that studies hurricanes. Then swirl all of those sounds into a shell-shaped silver sculpture that looks like something from a sci-fi film.

Put the shell at the Huntington Library in southern California, walk inside, and you have Orbit Pavilion — an immersive piece of art and science communication designed to envelop people in sounds that represents the orbital movements of NASA’s fleet of Earth-observing satellites.

Dan Goods and David Delgado, artists working at The Studio at NASA Jet Propulsion Laboratory, initially developed the sound concept. They commissioned sound artist Shane Myrbeck to compose the soundscape, and Jason Klimoski and Lesley Chang of StudioKCA to envision and design a form.

Myreck describes the pavilion’s soundscape this way:

“The piece is in two parts, each with one sound following the path of a satellite. One section demonstrates the movement of the satellites by compressing a day’s worth of trajectory data into one minute, so listeners are enveloped by a symphony of 19 sounds swirling around them. The other section represents the real-time position of the spacecraft: each satellite currently in our hemisphere will “speak” in sequence, and when a sound is playing, if a listener points to the direction of the sound, they are pointing to the satellite orbiting hundreds of miles above us….These satellites are all part of Earth science missions, studying our atmosphere, oceans, and geology — they are helping us better understand how our planet is changing, and potentially how we can be better stewards of it. In that way I see them as kind of sentinels or protectors.”

The result, as Myrebeck had hoped, is both enveloping and comforting.

Information about the orbits of 17 satellites and two sensors on the International Space Station feed into the Orbit Pavilion. Image Credit: StudioKCA

The current fleet of Earth-observing satellites. Image Credit: NASA/EOSPSO

For a deeper dive into the diversity of the data these satellites collect, try searching a satellite’s name on Visible Earth. Or browse NASA Earth Observatory’s global maps sections and Image of the Day archive.

For instance, the map below helped me understand our planet a little bit better. It depicts more than a decade of cloudiness data as observed by the MODIS sensor. Blue shows areas where clouds were infrequent; white indicates areas where they were common.

Image Credit: NASA Earth Observatory, based on data from MODIS.

 

Explore Earth Your Way

April 19th, 2018 by Jennifer Brennan

Today’s blog is re-posted from NASA.gov in recognition of the agency’s Earth Day activities.

NASA’s Worldview app lets you explore Earth as it looks right now or as it looked almost 20 years ago. See a view you like? Take a snapshot and share your map with a friend or colleague. Want to track the spread of a wildfire? You can even create an animated GIF to see change over time.

Through an easy-to-use map interface, you can watch tropical storms developing over the Pacific Ocean; track the movement of icebergs after they calve from glaciers and ice shelves; and see wildfires spread and grow as they burn vegetation in their path. Pan and zoom to your region of the world to see not only what it looks like today, but to investigate changes over time. Worldview’s nighttime lights layers provide a truly unique perspective of our planet.

What else can you do with Worldview? Add imagery by discipline, natural hazard, or key word to learn more about what’s happening on this dynamic planet. View Earth’s frozen regions with the Arctic and Antarctic views. Take a look at current natural events like tropical storms, volcanic eruptions, wildfires, and icebergs at the touch of a button using the “events” tab.

https://worldview.earthdata.nasa.gov

Worldview is an open-source project at NASA. All data, software, and services are freely available to anyone for any purpose.  You can participate in the software development by visiting:

https://github.com/nasa-gibs/worldview.

In Case You Missed It – Dance of a Melting Snowflake

April 13th, 2018 by Mike Carlowicz

Today’s post is a reprint of recent story by Carol Rasmussen of NASA’s Earth Science News Team.

NASA has produced the first three-dimensional numerical model of melting snowflakes in the atmosphere. Developed by scientist Jussi Leinonen of NASA’s Jet Propulsion Laboratory, the model provides a better understanding of how snow melts. This can help scientists recognize the signature (in radar signals) of heavier, wetter snow the kind that snaps power lines and tree limbs and could be a step toward improving predictions of this hazard.

Leinonen’s model reproduces key features of melting snowflakes that have been observed in nature. First, meltwater gathers in any concave regions of the snowflake’s surface. These liquid-water regions then merge to form a shell of liquid around an ice core, and finally develop into a water drop. The modeled snowflake shown in the video is less than half an inch (one centimeter) long and composed of many individual ice crystals whose arms became entangled when they collided in midair.

Leinonen said he got interested in modeling melting snow because of the way it affects observations with remote sensing instruments. A radar “profile” of the atmosphere from top to bottom shows a very bright, prominent layer at the altitude where falling snow and hail melt much brighter than atmospheric layers above and below it. “The reasons for this layer are still not particularly clear, and there has been a bit of debate in the community,” Leinonen said. Simpler models can reproduce the bright melt layer, but a more detailed model like this one can help scientists to understand it better, particularly how the layer is related to both the type of melting snow and the radar wavelengths used to observe it.

A paper on the numerical model, titled “Snowflake melting simulation using smoothed particle hydrodynamics,” recently appeared in the Journal of Geophysical Research – Atmospheres.

 

The location of mid-latitude storm tracks are marked with an L. The location of the jet stream is marked with a dot. And the place where air sinks between Hadley Cells and Mid-latitude Cells is marked with an H. The left side of the chart depicts the Southern Hemisphere; the right side depicts the Northern Hemisphere. Chart by George Tselioudis/NASA. The cloud data was collected by CloudSat.

The concentrations of greenhouse gases in Earth’s atmosphere have risen rapidly during the past century, mainly because of fossil fuel burning. Some of the effects of this are pretty straightforward: more carbon dioxide in the atmosphere means air temperatures will rise; ice in the high latitudes will begin to melt; and sea level will rise.

That seems pretty straightforward, right? But there are some areas where the changes will be more complicated. For instance, what will all of that extra carbon dioxide means for how air circulates, for the position of the jet stream, and for how clouds are distributed in the atmosphere?

George Tselioudis, a climate scientist at NASA’s Goddard Institute for Space Studies, did a nice job of explaining this as part of a post he wrote recently. In case you are not familiar with some of the scientific terms, I have added links to web sites that explain them in more detail. I also added some additional explanations to make his description a little clearer.

Take it away, George:

Atmospheric circulation, when examined using a simplified, two-dimensional view (such as the figure above), is dominated by two major features. The first is a large feature called the Hadley cell, which lifts air in the Inter-Tropical Convergence Zone (ITCZ), moves it at high altitudes towards the poles, and sinks it again to the surface in the subtropical regions. The second feature is a very strong river of air, known as the jet stream, that flows from west to east in the middle latitudes of each hemisphere. The meanders of the jet stream produce the storm tracks that are the major weather makers in the mid-latitude regions.

Image Credit: NASA.

George did not include it in his post, but here is a useful chart that lays out the locations of Hadley cells and the other higher-latitude cells. Now look back at the figure at the top of this page, and let’s go back to George.

The subsiding zones at latitudes between 20° and 30° North and South are noted by the letter ‘H’; the jet stream is in each hemisphere is marked with a dot; and the storm tracks are noted with an ‘L’. The circulation is superimposed on the distribution of the world’s clouds, derived from NASA CloudSat satellite observations. Areas with the most clouds are red and yellow.

Note: The CloudSat data are key. There are plenty of diagrams that show how global circulation patterns work (in fact, I have included one more below). But there are few that show you where clouds actually form and, crucially, at what altitude those clouds form.

Image by the Center for Multiscale modeling of Atmospheric Processes.

George continues:

It is apparent how the clouds relate to the circulation features. The narrow zone of uplift in the tropics produces high, thick clouds in the ITCZ (which is near the equator). The areas of subsidence in the subtropics produce extensive fields of low clouds, more extensive and deep in the southern than in the northern hemisphere, while the storms embedded in the jet stream produce deep, high clouds that extend throughout the Earth’s troposphere.

It is worth looking carefully at the figure at the top of the page and tracing out the features that Tselioudis describes. Whether clouds are low or high leads to different effects on climate. Low clouds primarily reflect solar radiation and cool the surface of the Earth. In contrast, high clouds tend to have a warming effect on the surface and atmosphere.

Now let us look at the key claim that Tselioudis and other climate scientists make about how global warming will affect circulation patterns. In short, scientists expect Hadley cells to expand so that the edges (where air descends) move toward the poles. In other words, the tropics will expand.

And that is exactly what has happened over the past few decades:

Observations of the past 35 years indicate that, as the Earth has warmed, these circulation features are moving towards the poles. The Hadley cell shows a clear signal of poleward expansion, while poleward movement is present but less clear in the jet stream and mid-latitude storm tracks. We found that the two quantities that correlate significantly and consistently in all ocean basins and seasons are the Hadley cell extent and the high cloud field: when the Hadley cell edge moves poleward, the high cloud field also shifts towards the poles, and vice versa.

Still following? Good, because this is where things get more complicated. Though Hadley cells are expanding in both the Northern and Southern Hemispheres, the effects on clouds and climate are different in each hemisphere. Here is how Tselioudis puts it:

However, this coordinated movement does not have the same effect in the two hemispheres. In the northern hemisphere, the poleward movement of the high clouds opens up a “cloud curtain” that lets more sunlight into the ocean surface, thus producing warming at the surface. But in the southern hemisphere, the poleward contraction of the high clouds is balanced by an expansion of the already extensive low cloud decks, which ends up blocking more sunlight and producing a small surface cooling.

A map of Earth showing the global cloud cover on July 11, 2005, based largely on observations by the MODIS sensor on the NASA Terra satellite. Most clouds form in bands near the equator and along lines of latitude roughly 60 degrees North and South of the equator.

Why does this matter? According to Tselioudis, representing this detail correctly in climate models is critical to determining how much warming will result from a given increase of greenhouse gases. Climatologists call this climate sensitivity. Many climate models do not represent Hadley Cell expansion correctly yet; specifically, the models do not account for the fact that the Hadley cells have grown wider. Tselioudis’s research shows that the models that do match real-world observations of clouds have a lower sensitivity to greenhouse gases (a climate sensitivity near 3° Celsius compared to between 4°C and 5°C).

If Tselioudis is right, that is a piece of mildly good news for the planet from the complicated world of cloud climate science.

For more details, read the post Tselioudis wrote for GISS. Also, take a look at this June 2017 article and this May 2016 study and news release.