NOAA ATMOSPHERIC MONITORING FACILITY IN HAWAII MARKS MILESTONE
Mauna Loa Turns 50

June 29, 2006 — The NOAA Mauna Loa Observatory in Hawaii marked its 50th anniversary as the premier atmospheric monitoring facility in the world. The facility was dedicated on June 28, 1956, as a site to measure solar radiation and atmospheric trace gases that could change Earth's climate. It later began monitoring air quality and changes in the stratosphere, the latter primarily to track the ozone hole and its recovery. MLO is best known for its record of the continuous rise of carbon dioxide in Earth's atmosphere, measurements originated by the late Charles David Keeling. Today, MLO keeps tabs on more than 50 chemical species in Earth's atmosphere. (Click NOAA image for larger view of the NOAA Mauna Loa Observatory in Hilo, Hawaii. Please credit “NOAA.”)

The original "slope building," now known as the Keeling Building, sits amid a ten-structure complex built in stages as the observatory's mission expanded. Meanwhile, lower-elevation sites sprung up around the island. Today, air samples are collected at Cape Kumukahi, the eastern most point of the island of Hawaii; weekly ozonesonde flights are prepared and launched at the former Hilo airport; and administration and data processing occur at an office in Hilo.

MLO data on a host of atmospheric gases and aerosols, solar radiation and standard meteorological measurements are freely available online, many in real time.

A COLORFUL START
The first venture into monitoring the atmosphere from Mauna Loa was a simple weather station, slightly larger than an outhouse, constructed at the summit in 1951. One photo of the December dedication—an outdoor barbecue in 22 degrees Fahrenheit with snow squalls—shows a clump of men hunched over in thick jackets under a lopsided "U.S. Weather Bureau" sign. The station closed three years later because of "road deterioration and crew fatigue." (Click NOAA image for larger view of researchers braving bitter-cold temperatures and snow squalls to dedicate the summit building in December 1951. A barbecue followed. Please credit “NOAA.”)

The current observatory was conceived in June 1955 at Sunspot, New Mexico. Robert H. Simpson, head of the Florida Hurricane Center, happened to visit Ralph Stair of the National Bureau of Standards at the NBS Sunspot observatory on a bad sky day: the sun shined weakly through a blanket of brightly reflecting dust stirred up by a windstorm over the adjacent desert.

Dusty skies were not popular with NBS researchers trying to measure solar energy at high intensity, as well as the total amount and vertical distribution of ozone in the atmosphere. They had already searched the entire continental U.S. for consistently clear skies with direct, intense sunlight. They also needed a view of Venus in the daylight, unobscured by clouds and dust. They had found nothing better than Sunspot. It was Simpson who suggested a mountaintop in Hawaii.

The so-called slope building was designed as a "durable shelter for practical use in all kinds of weather." At 11,140 feet—considerably lower than the doomed weather station—researchers could drive to the site in the two-wheel drive vehicles of the time. Photos of the 1956 dedication, in June this time, show women on site, and fresh-baked buns and homemade preserves are displayed on the table. One man's sunglasses suggest the NBS team had found their clear skies. In fact, the north slope of Mauna Loa had a terrific advantage as an observation site—nearby Mauna Kea provided a massive natural shield against wind, dust and pollutants. (Click NOAA image for larger view of the slope building, dedicated in June 1956, which was constructed of cinder blocks atop a concrete pad on the north slope of Mauna Loa. Please credit “NOAA.”)

The observatory came into being just in time for the wave of new science that emerged from the International Geophysical Year in 1957.

MAUNA LOA DATA TODAY: ATMOSPHERIC GASES
"Before the ozone hole, we didn't measure so many gases," says Russell Schnell, who directed the MLO on site from 1992 to 1997. Today, Schnell oversees Mauna Loa and other monitoring sites around the world from the NOAA Earth System Research Lab in Boulder. "Now we're always adding new measurements as the environment and chemistry change," says Schnell. "Almost everything we thought was stable is changing."

The graph of the rise of carbon dioxide (CO2) over the past five decades—the indisputable cornerstone of climate change research—has become one of the era's iconic images. Today, MLO data and other observations show CO2 is increasing at .53 percent, or two parts per million per year, according to Pieter Tans, who heads the ESRL group studying the carbon cycle and greenhouse gases. CO2 alone is responsible for 63 percent of the warming attributable to all greenhouse gases, he adds, and its share is expected to increase further because of the very long residence time of the emitted CO2 in the atmosphere-ocean system. (Click NOAA image for larger view of the Keeling Curve. The NOAA Mauna Loa Observatory is most famous for its continuous monitoring and recording of the rise of carbon dioxide in Earth's atmosphere. Please credit “NOAA.”)

"Carbon dioxide is a trace gas, a very small part of the atmosphere, so we need to track it very accurately," says Schnell. "Even small changes in CO2 have a big affect on the atmosphere and ultimately on the climate."

Other images, such as the graph showing the leveling of chlorofluorocarbons, or CFCs, following the Montreal Protocol, also are laden with history and meaning. The increase in their substitutes, hydrochlorofluorocarbons, or HCFCs, is now starting to decline, says ESRL scientist Jim Elkins, because of limitations built into the Protocol for industrial nations. Developing countries have until 2040 to phase out HCFCs, whose lifetimes are shorter than those of the original CFCs they replaced.

Another compound to watch is nitrous oxide, the third most powerful greenhouse gas and one also involved in stratospheric ozone destruction. N2O is increasing at .25 percent per year, according to Elkins, whose group studies both atmospheric trace gases and halocarbons. Thirty percent of the N2O entering the atmosphere is produced from nitrate and ammonia fertilizers, fossil-fuel burning and other human-related activities. The remaining 70 percent comes from the natural decay of biomass in forests and oceans.

Currently MLO is getting a head start on gases expected to become more important in the future. Sulfur hexafluoride, for example, is increasing at 5 percent per year. Although its atmospheric concentrations are still very low (5-6 parts per trillion), it's the most powerful greenhouse gas molecule in existence and has a lifetime of about 1,000 years. It's widely used in electric transformers to prevent arcing, and it's not going away, says Schnell.

THE STRATOSPHERE
In 1997, a large new building was constructed at the MLO site to house components of the international Network for the Detection of Stratospheric Change. The program's U.S. components are supported by both NOAA and NASA. Now called the Network for the Detection of Atmospheric Composition Change, the NDACC is a set of high-quality remote-sounding research stations for observing and understanding the physical and chemical state of the stratosphere, according to the program's Web site. The network originally targeted ozone and key ozone-related chemical compounds. While monitoring the long-term evolution of the ozone layer is still a priority, NDACC goals now include the detection of trends in overall atmospheric composition, understanding their impacts on the stratosphere and troposphere, and establishing links between climate change and atmospheric composition.

SOLAR RADIATION
Solar radiation and its transmission through the atmosphere have been measured at MLO since shortly after the slope building was dedicated. It's no surprise that solar radiation at the Earth's surface drops sharply when large volcanoes erupt, sending light-blocking aerosols around the globe. More recently, however, the greater concern is pollution from industrial and transportation sources—many of them in China.

"We're seeing a small change in the levels of solar radiation reaching the surface," says Schnell, pointing to wavy lines hovering below normal for the past decade. Although minuscule, how this solar reduction plays into a warming climate remains to be seen. (Click NOAA image for larger view of chart showing solar radiation reaching the Earth's surface has taken a dip in recent years. Please credit “NOAA.”)

MAUNA LOA's FUTURE
With long-term observations, the future is always present.

"We are using techniques and calibrations that will keep the data meaningful 200 years from now," says Schnell. "In 2200 people will understand exactly what the measurements from 1958 or 2054 or 2119 mean. They will be exactly compatible, traceable and intercomparable."

"We'll be here hundreds of years from now, observing the atmosphere with the same consistency," he adds, as though anything less is unimaginable.

In 2007, NOAA, an agency of the U.S. Commerce Department, celebrates 200 years of science and service to the nation. From the establishment of the U.S. Coast and Geodetic Survey in 1807 by Thomas Jefferson to the formation of the Weather Bureau and the Bureau of Commercial Fisheries in the 1870s, much of America's scientific heritage is rooted in NOAA.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of the nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners and more than 60 countries to develop a global monitoring network that is as integrated as the planet it observes.

Relevant Web Sites
NOAA Mauna Loa Observatory

NOAA Earth System Research Lab

NOAA Global Monitoring Division

Media Contact:
Anatta, NOAA Research, (303) 497-6288