Author: khansen

Making a Splash with Satellite Hydrology

It has long been suspected that dams and reservoirs provide extra moisture to the atmosphere and increase rainfall in the area around the reservoir. In December 2009, Faisal Hossain, of Tennessee Technological University, demonstrated that certain dams could make such rainfall events more extreme and frequent. The research catapulted Faisal and his research group — Sustainability, Satellites, Water and Environment (SASWE) — into the media spotlight, including a February 2010 interview with The Naked Scientists that aired live on the BBC and a feature in National Geographic News.

Hossain and his SASWE group — largely funded by NASA grants — also work to improve the ability of developing nations to monitor water resources that cross national boundaries. In April 2010, the group will be recognized by the National Association of Environmental Professionals with an education excellence award. WhatOnEarth caught up with Hossain to learn more about the group’s work and outreach efforts.

WhatOnEarth: What is satellite hydrology?

Hossain: We study the availability and movement of water on (surface), under (ground) and above (rain) earth’s surface by looking down from satellites in space. Today there are many satellites with instruments that can ‘read’ how much water might be flowing in a river or in the air, and also how wet the ground might be. Because Earth is 75 percent ocean and because land regions are too vast and expensive to completely survey, satellites provide the cheapest convenient and global way of monitoring the flow of water.

WhatOnEarth: What are some of the water issues your group is looking to solve? How?

Hossain: Today, more than 50 percent of the global surface flow is shared by multiple nations. Also, the numerous artificial reservoirs — more than 100,000 — built mostly in the upstream nations not only have vital implications on water supply for nations downstream, but they can also act as catalysts for increased flooding through heavier precipitation.

Without adequate treaties for trans-border cooperation, and without adequate knowledge of how dams alter climate, future water scarcity due to climate change and aging water infrastructure is likely to make nations more vulnerable to water disasters. SASWE is probably the first to demonstrate clearly the value of planned space-borne water measuring missions, such as the Global Precipitation Measurement (GPM) mission, and how they may improve disaster preparedness and environmental management.

WhatOnEarth: Does your research impact people’s lives?

Hossain: Many developing countries in Asia, Africa, and South America, are flood prone and yet unable to forecast floods due to the lack of basin-wide rainfall and stream flow data. Our group is helping to validate and improve NASA’s Global Flood Detection System, which uses rainfall data from NASA’s Tropical Rainfall Measuring Mission, and will also use NASA’s planned GPM mission.

For instance, Bangladesh is situated downstream of the Ganges-Brahmaputra-Meghna basin but does not receive any upstream river flow and rainfall information in real time from India during the critical monsoon season. Bangladeshi authorities measure river flow at staging points where the three major rivers enter Bangladesh and at other points downstream. On the basis of these data, it is possible to forecast flood levels in the interior and south of Bangladesh with only two to three days lead time. Theoretically, future NASA satellite missions could increase this lead time to anywhere from 7 to 14 days depending on the time for stream-flow to drain out from the Himalayas to the Bay of Bengal.

A longer forecasting range would improve decision-support tools that ingest these warnings. For example, 7- to 10-day forecasts are much more useful than daily forecasts in monsoon-affected Asian countries for informing farmers of the potential benefits of delayed sowing or early reaping of crops. A 21-day forecast is considered most ideal. Extended forecasts also assist in economic decision-making through early disbursement of loans to rehabilitate regions that might be affected by floods.

WhatOnEarth: How are public outreach and education part of your team’s mission?

Hossain: We are working with developing nations for climate change adaptation under a joint program with the Institute of Water Modeling (Bangladesh), Tennessee Technological University, and Ohio State University. In this program, staff from Bangladesh receive training each year on environmental management, stewardship and state-of-the-art satellite technology for adapting to climate change. The staff returns home and explores ways to implement the knowledge in their environment and to serve as a model for other developing nations.

Image Details: Water within a generic watershed boundary (red) can cross many political boundaries (top image). Both images are courtesy of Faisal Hossain, Tennessee Technological University.

— Kathryn Hansen, NASA’s Earth Science News Team

NASA Readies for Spring 2010 Ice Bridge Campaign

The following is a cross-post from our sister blog at NASA’s Operation Ice Bridge. For more frequent updates on the Ice Bridge mission, visit https://www.nasa.gov/topics/earth/features/ice_bridge/index.html

Credit: John Sonntag/Wallops Flight Facility

In August 2008, NASA scientist John Sonntag, of NASA’s Wallops Flight Facility in Wallops Island, Va., captured this view of a small iceberg as it moved down the Narsarsuaq fjord in southern Greenland. “I spent about half an hour watching that little berg, which was in the process of disintegrating during the time I was watching,” Sonntag said. “It went from a complete, small berg to a collection of floating ice rubble within that small span of time. The place was so quiet that the noise of the berg softly coming apart was the only sound present.”

Sonntag’s observation took place during the 2008 NASA and Center for Remote Sensing of Ice Sheets (CReSIS) airborne deployment in Greenland. This spring, Sonntag and other scientists return to the Arctic for big picture and little picture views of the ice as part of NASA’s six-year Operation Ice Bridge mission — the largest airborne survey of Earth’s polar ice ever flown — now entering its second year. The project team is finalizing flight paths over Greenland’s ice sheet and surrounding sea ice, where scientists will collect measurements, maps and images from a suite of airborne instruments. Such information will help scientists extend the record of changes to the ice previously observed by NASA’s Ice, Cloud, and land Elevation Satellite (ICESat), while uncovering new details about land-water-ice dynamics.

NASA aircraft have made numerous science flights over Greenland, most recently during the spring 2009 Ice Bridge campaign and also in 2008 as part of the NASA/CReSIS deployment. Smaller-scale airborne surveys have been made by William Krabill, of NASA Wallops, and colleagues nearly every spring since 1991.

Visit the Operation Ice Bridge Web page throughout the spring 2010 campaign for news, images, and updates from the field. Flights from Greenland are scheduled to begin no sooner than March 22.

— Kathryn Hansen, NASA’s Earth Science News Team

Up Close with Ice Bridge

NASA and partners are nearing the end of the 2009 Antarctic campaign of Operation Ice Bridge — a multi-year airborne survey to study Earth’s polar ice sheets, ice shelves and sea ice. Data collected from the DC-8 aircraft will help scientists monitor changes in West Antarctica and bridge the gap between the ICESat and ICESat-2 satellites. Also, the close-up look — not possible from satellites — will help scientists learn more about the region’s ice dynamics.

Ice Bridge scientist Seeyle Martin.  Credit: NASA

The detailed look with lasers and radar, sometimes from just 1,000 feet above the ice, is now returning a wealth of scientific information about the ice surface and what’s below. And to the human eye, the low-altitude view shows West Antarctica’s intricacies: the vast expanse of white giving way to deep crevasses and volcanoes, and sea ice resembling pancakes and oil slicks.

The 2009 Operation Ice Bridge campaign concludes no later than Nov. 21. Want to follow the remainder of the flights? Here’s how to connect:

  • Webisodes – Watch this series of YouTube videos for a behind-the-scenes look at Ice Bridge mission planning and flights in Antarctica.

  • Image gallery – Curious what pancake ice looks like or want to take a peek inside the DC-8? Check out the image gallery for photos added throughout the mission

  • Blog – Read about the campaign straight from the scientists and public affairs officers on site.

  • Twitter – Be among the first to know if a flight took off or if it was grounded due to weather, and discover the target of most flights — glacier, ice sheet or sea ice?

–Kathryn Hansen, NASA’s Earth Science News Team

How Do Global Soot Models Measure Up?


A image from a simulation that shows the spread of black carbon aerosols in Asia. Areas where the air was thick with
the pollution particles are white, while lower concentrations are transparent purple. (Credit: Earth Observatory)

As NASA atmospheric scientist Eric Wilcox recently told Time magazine, emerging evidence suggests that a short-lived type of air pollution called black carbon—known popularly as soot—can exacerbate global warming by absorbing incoming solar radiation.

Yet pinning down precisely how much the black carbon exacerbates warming is no easy task, research conducted by Goddard Institute for Space Studies climatologist Dorothy Koch suggests. The study, published in Atmospheric Chemistry and Physics tracked how the predictions from 17 global black carbon models compared with actual measurements collected by airplane, satellite, and ground-based sensors. It shows, among other things, that models generally underestimate black carbon’s warming effect on climate.

Koch tested all the models in three ways. In the simplest of the three, she compared the models’ predictions to the amount of black carbon measured at the surface, finding that they matched real life reasonably well.

Her second test compared the models’ predictions to black carbon measurements made higher in the atmosphere using airplanes, and the results were much less clear cut. Though the models usually had too much black carbon over pollution sources, most had too little over remote regions such as the Arctic.

Koch’s final and most important test looked at how much solar radiation black carbon actually absorbs, an indicator of the amount of warming the particles actually produce. Again, the results were mixed. The models were largely accurate over North America and Europe, but were not for areas that have high levels of black carbon such as Central Africa, Southeast Asia, and the Amazon.

In a write-up on the Goddard Institute for Space Studies web site, Koch summarizes her findings this way:

We concluded from this study that most models have enough black carbon at ground level in polluted regions, too much in the atmosphere above source regions, but not enough in the Arctic where black carbon may play an important role in contributing to Arctic warming and ice/snow melt. The models’ soot generally does not absorb enough sunlight and therefore these models would underestimate black carbon heating effects. This probably results from underestimating the absorbing properties of the particles rather than the amount (mass) of black carbon.

Wondering how climate modelers can continue to close the gap between model predictions and reality? Koch put forward some advice on how to fine-tune the next generation of aerosols models. Her top three:

1) Account for mixing between black carbon and other components of the atmosphere,
2) Incorporate better measurements of particle size and source amount in some regions.
3) Continue to mine ongoing satellite and field campaigns for data about black carbon.

You can read more GISS science briefs and NASA news stories about black carbon here, here, and here.

–Adam Voiland, NASA’s Earth Science News Team

Science Advice for an Evolving Ozone Layer Agreement


NASA scientist Paul Newman briefly stopped in Cairo, Egypt, on his way to the
Montreal Protocol meeting in Port Ghalib. Credit: Paul Newman

The view of the Red Sea was spectacular, but it was all work and no play for NASA atmospheric scientist Paul Newman during a recent trip to Port Ghalib, Egypt. That’s where scientists, policymakers, and representatives of the United Nations Environment Programme, convened Nov. 4-8 for an annual meeting to discuss and amend the Montreal Protocol — the international agreement that regulates ozone-depleting substances. Newman attended as co-chair of the Scientific Assessment Panel and gave us an inside look.

Q: Scientists use satellites and computer models to better understand the recovery of the ozone layer. How does this kind of science contribute to the policy decisions?
A: The Montreal Protocol regulates gases that destroy ozone, also known as ozone depleting substances (ODSs). The most famous of these are the chlorofluorocarbons (CFCs) that were used in spray cans and as refrigerants. Science provides that foundation for the Protocol. We used (and still use) models to predict the evolution of ozone in our atmosphere in response to the regulations made by the signatory countries. Satellite, aircraft, balloon, and ground observations provide a check on our model estimates. If you can’t simulate the past, it’s hard to claim that you can predict the future.

Q: What is involved in a typical day as “co-chair of the scientific assessment panel”?
A: We’re commonly referred to as the SAP. Not a great acronym for the scientists! In any case, we are the “on-the-spot” science advisors on all policy questions. 

In a typical day, there is a lot of discussion amongst the delegates about technical issues. Delegates actively discuss “critical use exemptions.” For example, methyl bromide is used as a fumigant. Plants, flowers, vegetables are all fumigated to help preserve them or to stop the spread of invasive species such as fruit flies. Without some sort of fumigation, entire farming industries might be destroyed. However, methyl bromide is also an ozone depleting substance. The SAP provides information on methyl bromide as an ozone depleting substance. For example, if we stop all methyl bromide usage, how much will this help the ozone layer?

Q: Why is there the need to revisit the Montreal Protocol with regular meetings?
A: The Protocol was designed to be an evolving agreement. Originally, the production of ODSs was limited, not stopped. Over the years, policymakers strengthened the original agreement such that all CFC production is now stopped. However, there is still some usage in developing countries, and there are stocks of ODSs that could potentially be destroyed. The nations get together twice per year to talk over the needs for evolving or strengthening the agreement.

Q: What are hydrofluorocarbons (HFC’s), and why do you think a proposal to include HFCs in the protocol was unsuccessful this year?
A: Hydrofluorocarbons, or HFCs, are used as refrigerants, and they don’t destroy ozone. However, HFCs are powerful greenhouse gases.

When CFCs were banned, alternative refrigerants were developed to take their place. The initial alternatives were hydrochlorofluorocarbons (HCFCs). HCFCs were still ozone depleting substances, but they had much shorter lifetimes than CFCs, and hence, were less ozone dangerous than CFCs. In 2007, the HCFCs were banned under the Montreal Protocol and are now being phased out.

HCFCs are now being replaced by HFCs. The Montreal Protocol shifted from the ozone dangerous CFCs to the less dangerous HCFCs, and now to the ozone safe HFCs. By banning CFCs, the Montreal Protocol had a double benefit: less ozone depletion and less greenhouse gas warming (CFCs are powerful greenhouse gases).

However, by banning CFCs, the Montreal Protocol created a demand for the ozone-safe HFCs (people still want air conditioners). All of the climate benefit gained by banning CFCs might be lost as HFCs increase in our atmosphere. Hence, some people are calling for the banning of HFCs under the Montreal Protocol, in spite of the fact that HFCs don’t destroy ozone. By banning HFCs, the Montreal Protocol would become both an ozone treaty and a climate treaty.

The HFC amendment did not go through for a number of reasons. The primary reason is that many countries believe that HFCs are climate related and should therefore be regulated under the Kyoto Agreement.

Q: What current research do you think could impact future meetings?
A: The Montreal Protocol is evolving into both an ozone and climate agreement. It is still necessary for scientists to investigate the impact of human-produced chemicals on both ozone and climate. Every day new chemicals are being proposed for various uses, and the scientists need to assess the environmental impact to select those chemicals that are non-toxic and environmentally safe.

–Kathryn Hansen, NASA’s Earth Science News Team