Global & Disaster Medicine

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NASA: A Chilly End to 2017 for the Northeast

A Chilly End to 2017 for the Northeast

As 2017 drew toward a close, Arctic air spilled into the eastern United States and Canada for several days. Blasts of bitterly cold air set up a white Christmas for many Americans, and forecasters are expecting New Year’s Eve celebrations to be the coldest in recent memory for many areas.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image of the frozen Northeast landscape on December 28, 2017. Brisk northwesterly winds created rows of “cloud streets” as cold air blew over Lake Ontario and the Atlantic Ocean. A layer of snow covered much of New England and upstate New York.

Cloud streets are long parallel bands of cumulus clouds that form when cold air blows over warmer waters and a warmer air layer (temperature inversion) rests over the top of both. The comparatively warm water gives up heat and moisture to the cold air above, and columns of heated air called thermals naturally rise through the atmosphere. The temperature inversion acts like a lid. When the rising thermals hit it, they roll over and loop back on themselves, creating parallel cylinders of rotating air. As this happens, the moisture cools and condenses into flat-bottomed, fluffy-topped cumulus clouds that line up parallel to the direction of the prevailing winds.

While the cold streak has not broken all-time records, it is breaking records for individual days. On the day the image was acquired, weather observers on Mount Washington (New Hampshire) recorded a daily record low of -34 degrees Fahrenheit (-36° Celsius). Baltimore, Boston, Flint, New York, Montreal, and Toronto Cities have seen records fall during this cold snap.

When the ball drops in New York City on New Year’s Eve, forecasters expect air temperatures of 10°F (-12°C), with wind chills of -5°F ( -15°C). The last time it was so cold was in 1962; the record for the coldest ball drop occurred in 1917, when the air temperature was just 1°F (-17°C), according to Jason Samenow of the Capital Weather Gang.

The cold weather pattern has its origins in a large bulge, or ridge, in the jet stream that has brought unseasonably warm weather to Alaska. On the east side of this ridge, a trough in the jet stream plunged southward, bringing plenty of Arctic air with it. This orientation of the jet stream, which looks similar to the greek letter omega, is known as an omega block.

NASA image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response. Story by Adam Voiland.

Terra – MODIS

9/28/17: Puerto Rico Landscape Ravaged by Hurricane Maria

Puerto Rico Landscape Ravaged by Hurricane Maria

acquired September 26, 2017 download large image (1 MB, JPEG, 2490×2713)
Puerto Rico Landscape Ravaged by Hurricane Maria

acquired September 23, 2016 download large image (1 MB, JPEG, 2490×2713)
acquired September 23, 2016 download large image (406 KB, JPEG, 720×480)
acquired September 26, 2017 download large image (342 KB, JPEG, 720×480)

Hurricane Maria tore across Puerto Rico on September 20, 2017, ravaging both urban and rural areas with category 4 winds and intense rainfall for several days. Most of the electric power grid and telecommunications network was knocked offline; towns both inland and at the coast were swamped with floodwaters and storm surges; and the lush green landscape turned brown from damaged vegetation and mud and debris deposits.

On September 26, 2017, the Operational Land Imager (OLI) on the Landsat 8 satellite captured some of the first natural-color satellite images of Puerto Rico after Hurricane Maria. Cloud cover is common in the tropics and has been particularly bad in the days since the storm, so researchers have been unable to see much from orbit.

The images above show the Rio Grande de Loíza, the island’s largest river by volume, where it meets the Atlantic Ocean several miles east of San Juan and west of Suárez. The images below show an interior portion of the island around the Lago Loíza reservoir, south of San Juan and north of Caguas. In each pair the second image shows the same area one year ago (September 23, 2016) so as to provide a proper seasonal comparison. (Note: the green color of the lake in 2016 could be an algae bloom or some other form of water vegetation.)

NASA’s Disasters Program has delivered to the Federal Emergency Management Agency (FEMA) a map of areas in eastern Puerto Rico that have likely been damaged as the result of the landfall of Hurricane Maria. The “damage proxy map” was created by the Advanced Rapid Imaging and Analysis team (Jet Propulsion Laboratory) and derived from synthetic aperture radar images from the European Space Agency’s Copernicus Sentinel-1A and Sentinel-1B satellites.

The National Oceanic and Atmospheric Administration is making aerial surveys of the U.S. states and territories affected by hurricanes Harvey, Irma, and Maria. Click here to see photos as they become available.

NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Story by Mike Carlowicz.

Landsat 8 – OLI
Landsat 8 – TIRS

3 Hurricanes: NASA

Credit:  NASA

NASA: Irma on 9/5/17

Hurricane Irma Strengthens


NASA: Hermine from Outer Space

Hurricane Hermine Approaches Florida

NY Times

NASA: The Alberta wildfire smoke becomes entrained within the clouds causing it to twist within the circular motion of the clouds and wind.

Smoke is drawn in to and transported along with the clouds over Canada.

NASA’s Aqua satellite captured this image of the clouds over Canada.  Entwined within the clouds is the smoke billowing up from the wildfires that are currently burning across a large expanse of the country.  The smoke has become entrained within the clouds causing it to twist within the circular motion of the clouds and wind.  This image was taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Aqua satellite on May 9, 2016.

Image Credit: NASA image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC
Caption: Lynn Jenner

Last Updated: May 10, 2016
Editor: Lynn Jenner

In September and October 2015, tens of thousands of fires sent clouds of toxic gas and particulate matter into the air over Indonesia.

Fires Put a Carbon Monoxide Cloud over Indonesia

In September and October 2015, tens of thousands of fires sent clouds of toxic gas and particulate matter into the air over Indonesia. Despite the moist climate of tropical Asia, fire is not unusual during those months. For the past few decades, people have used fire to clear land for farming and to burn away leftover crop debris. What was unusual in 2015 was how many fires burned and how many escaped their handlers and went uncontrolled for weeks and even months.

To study the fires, scientists in Indonesia and around the world have been using many different tools—from sensors on the ground to data collected by satellites. The goal is to better understand why the fires became so severe, how they are affecting human health and the atmosphere, and what can be done to prepare for similar surges in fire activity in the future.

While some NASA satellite instruments captured natural-color images of the smoky pall, others focused on gases that are invisible to human eyes. For instance, the Measurement of Pollution in the Troposphere (MOPITT) sensor on Terra can detect carbon monoxide, an odorless, colorless, and poisonous gas. As shown by the map above, the concentration of carbon monoxide near the surface was remarkably high in September 2015 over Sumatra and Kalimantan.

“The 2015 Indonesian fires produced some of the highest concentrations of carbon monoxide that we have ever seen with MOPITT,” said Helen Worden, a scientist at the National Center for Atmospheric Research. Average carbon monoxide concentrations over Indonesia are usually about 100 parts per billion. In some parts of Borneo in 2015, MOPITT measured carbon monoxide concentrations at the surface up to nearly 1,300 parts per billion.

While all types of wildfires emit carbon monoxide as part of he combustion process, the fires in Indonesia released large amounts of the gas because in many cases the fuel burning was peat, a soil-like mixture of partly decayed plant material that builds up in wetlands, swamps, and partly submerged landscapes.

Read more about studies of Indonesia’s fire season in our new feature: Seeing Through the Smoky Pall.

NASA Earth Observatory map by Joshua Stevens and Jesse Allen, using data from the MOPITT Teams at the National Center for Atmospheric Research and the University of Toronto. Caption by Adam Voiland.

Terra – MOPITT

NASA: Soil moisture in USA, 2015

Soil Moisture in the United States

Deluge in the Amargosa and Death Valleys, November 4, 2015

Deluge in the Amargosa and Death Valleys

The animation above shows satellite-based estimates of rainfall from a particularly large storm that passed over the area on October 18. The rainfall data are from the Integrated Multi-Satellite Retrievals for GPM (IMERG), a product of the Global Precipitation Measurement mission. Green-white colors represent the largest rainfall totals, which in some areas reached upward of 70 millimeters (3 inches) during the 24-hour period displayed in the animation. These regional, remotely-sensed estimates may differ from the totals measured by ground-based weather stations.

Global Tree Cover

Is That a Forest? That Depends on How You Define It

30% Tree Cover

Color bar for Is That a Forest? That Depends on How You Define It


Is That a Forest? That Depends on How You Define It

10% Tree Cover




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