NASA Studying 2015 El Niño Event As Never Before

Every two to seven years, an unusually warm pool of water -- sometimes two to three degrees Celsius higher than normal – develops across the eastern tropical Pacific Ocean to create a natural short-term climate change event. This warm condition, known as El Niño, affects the local aquatic environment, but also spurs extreme weather patterns around the world, from flooding in California to droughts in Australia. This winter, the 2015-16 El Niño event will be better observed from space than any previous El Niño.

This year's El Niño is already strong and appears likely to equal the event of 1997-98, the strongest El Niño on record, according to the World Meteorological Organization. All 19 of NASA's current orbiting Earth-observing missions were launched after 1997. In the past two decades, NASA has made tremendous progress in gathering and analyzing data that help researchers understand more about the mechanics and global impacts of El Niño.

“El Niño is a fascinating phenomenon because it has such far-reaching and diverse impacts. The fact that fires in Indonesia are linked with circulation patterns that influence rainfall over the United States shows how complex and interconnected the Earth system is,” said Lesley Ott, research meteorologist at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

Using NASA satellite observations in tandem with supercomputer processing power for modeling systems, scientists have a comprehensive suite of tools to analyze El Niño events and their global impacts as never before. Throughout this winter, NASA will share the latest scientific insights and imagery updates related to El Niño.

For instance, scientists are learning how El Niño affects the year-to-year variability for fire seasons in the western United States, Amazon and Indonesia. El Niño may also affect the yearly variability of the ground-level pollutant ozone that severely affects human health. Researchers will be keenly focused on how the current El Niño will affect the drought in California.

“We still have a lot to learn about these connections, and NASA's suite of satellites will help us understand these processes in a new and deeper way,” said Ott.


This visualization shows side by side comparisons of Pacific Ocean sea surface height (SSH) anomalies of what is presently happening in 2015 with the Pacific Ocean signal during the famous 1997 El Niño. These 1997 and 2015 El Niño animations were made from data collected by the TOPEX/Poseidon (1997) and the OSTM/Jason-2 (2015) satellites.
Credits: NASA's Jet Propulsion Laboratory
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Many NASA satellites observe environmental factors that are associated with El Niño evolution and its impacts, including sea surface temperature, sea surface height, surface currents, atmospheric winds and ocean color. The joint NASA/NOAA/CNES/EUMETSAT Jason-2 satellite measures sea surface height, which is especially useful in quantifying the heat stored and released by the oceans during El Niño years.

NASA satellites also help scientists see the global impact of El Niño. The warmer than normal eastern Pacific Ocean has far-reaching effects worldwide. These events spur disasters like fires and floods. They change storm tracks, cloud cover and other weather patterns, and they have devastating effects on fisheries and other industries.  

NASA’s Earth-observing satellites help monitor those and other impacts by measuring land and ocean conditions that both influence and are affected by El Niño. For instance, NASA’s Global Precipitation Measurement Mission provides worldwide precipitation measurements every three hours. NASA’s Soil Moisture Active Passive mission measures soil moisture in the top layer of land. Both of these satellites are useful for monitoring drought, improving flood warnings and watching crop and fishing industries.

“NASA is at the forefront in providing key observations of El Niño and advancing our understanding of its role in shaping Earth’s weather and climate patterns,” said Duane Waliser, chief scientist of the Earth Science and Technology Directorate at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Bron:http://www.nasa.gov/feature/goddard/nasa-studying-2015-el-nino-event-as-never-before
 

NASA Examines El Niño's Impact on Ocean’s Food Source

El Niño years can have a big impact on the littlest plants in the ocean, and NASA scientists are studying the relationship between the two.

In El Niño years, huge masses of warm water – equivalent to about half of the volume of the Mediterranean Sea – slosh east across the Pacific Ocean towards South America. While this warm water changes storm systems in the atmosphere, it also has an impact below the ocean’s surface. These impacts, which researchers can visualize with satellite data, can ripple up the food chain to fisheries and the livelihoods of fishermen.


Strong El Nino events have a big impact on phytoplankton (in green), especially when the warm water pushes far to the east of the Pacific Ocean, as in 1997.
Credits: NASA/GoddardEl Niño’s mass of warm water puts a lid on the normal currents of cold, deep water that typically rise to the surface along the equator and off the coast of Chile and Peru, said Stephanie Uz, ocean scientist at Goddard Space Flight Center in Greenbelt, Maryland. In a process called upwelling, those cold waters normally bring up the nutrients that feed the tiny organisms, which form the base of the food chain.

"An El Niño basically stops the normal upwelling," Uz said. "There’s a lot of starvation that happens to the marine food web." These tiny plants, called phytoplankton, are fish food – without them, fish populations drop, and the fishing industries that many coastal regions depend on can collapse.



With NASA satellite data, and ocean color software called SeaDAS, developed at the Ocean Biology Processing Group at Goddard, Uz has been mapping where these important phytoplankton appear. Orbiting instruments like the Moderate Resolution Imaging Spectrometer on the Aqua satellite, and the Visible Infrared Imaging Radiometer Suite on the Suomi NPP satellite collect data on the color of the ocean. From shades of blue and green, scientists can calculate the amount of green chlorophyll – and therefore the amount of phytoplankton present.

The ocean color maps, based on a month’s worth of satellite data, can show that El Niño impact on phytoplankton. In December 2015, at the peak of the current El Niño event, there was more blue – and less green chlorophyll – in the Pacific Ocean off of Peru and Chile, compared to the previous year. Uz and her colleagues are also watching as the El Niño weakens this spring, to see when and where the phytoplankton reappear as the upwelling cold water brings nutrients back to the region.

"They can pop back up pretty quickly, once they have a source of nutrients," Uz said.

Researchers can also examine the differences in ocean color between two different El Niño events. During the large 1997-1998 El Niño event, the green chlorophyll virtually disappeared from the coast of Chile. This year’s event, while it caused a drop in chlorophyll primarily along the equator, was much less severe for the coastal phytoplankton population. The reason – the warmer-than-normal waters associated with the two El Niño events were centered in different geographical locations. In 1997-1998, the biggest ocean temperature abnormalities were in the eastern Pacific Ocean; this year the focus was in the central ocean. This difference impacts where the phytoplankton can feed on nutrients, and where the fish can feed on phytoplankton.

"When you have an East Pacific El Niño, like 1997-1998, it has a much bigger impact on the fisheries off of South America," Uz said.  But Central Pacific El Niño events, like this year’s, still have an impact on ocean ecosystems, just with a shift in location. Researchers are noting reduced food available along the food chain around the Galapagos Islands, for example. And there has been a drop in phytoplankton off the coast of South America, just not as dramatically as before.


Differences in December phytoplankton abundances are visualized for three years: during the strong East Pacific El Nino of 1997 (using SeaWiFS satellite data), during a normal year in 2013 (using data from MODIS on the Aqua satellite), and during the strong Central Pacific El Nino of 2015 (MODIS/Aqua).
Credits: Uz/NASA Goddard

Scientists have more tools on hand to study this El Niño, and can study more elements of the event, Uz said. They’re putting these tools to use to ask questions not just about ocean ecology, but about the carbon cycle as well.

"We know how important phytoplankton are for the marine food web, and we’re trying to understand their role as a carbon pump," Uz said. The carbon pump refers to one of the ways the Earth system removes carbon dioxide from the atmosphere. When phytoplankton die, their carbon-based bodies sink to the ocean floor, where they can remain for millions of years. El Niño is a naturally occurring disruption to the typical ocean currents, she said – so it’s important to understand the phenomenon to better attribute what occurs naturally, and what occurs due to human-caused disruptions to the system.

Other scientists at Goddard are investigating ways to forecast the ebbs and flows of nutrients using the center’s supercomputers, incorporating data like winds, sea surface temperatures, air pressures and more.

"It’s like weather forecasts, but for bionutrients and phytoplankton in the ocean," said Cecile Rousseaux, an ocean modeler with Goddard’s Global Modeling and Assimilation Office. The forecasts could help fisheries managers estimate how good the catch could be in a particular year, she said, since fish populations depend on phytoplankton populations. The 1997-1998 El Niño led to a major collapse in the anchovy fishery off of Chile, which caused economic hardships for fishermen along the coast.

So far, Rousseaux said, the phytoplankton forecast models haven’t shown any collapses for the 2015-2016 El Niño, possibly because the warm water isn’t reaching as far east in the Pacific this time around. The forecast of phytoplankton populations effort is a relatively new effort, she said, so it’s too soon to make definite forecasts. But the data so far, from the modeling group and others, show conditions returning to a more normal state this spring.

The next step for the model, she said, is to try to determine which individual species of phytoplankton will bloom where, based on nutrient amounts, temperatures and other factors – using satellites and other tools to determine which kind of microscopic plant is where.

"We rely on satellite data, but this will go one step further and give us even more information," Rousseaux said.

For more information, visit:
            www.nasa.gov/Earth

Bron: http://www.nasa.gov/feature/goddard/2016/nasa-examines-el-nino-impact-on-ocean-food-source