Earth Surface Lightens Up

EARTH OBSERVATION

Earth Lite - Sites from around the world were used to observe a solar-brightening trend on the planet's surface. Most show an increase in surface solar radiation after 1990, marked in yellow; decreases are shown in brown. (Triangles represent high-quality observations from the Baseline Surface Radiation Network; other sites from an earlier, updated archive are shown as crosses.) See larger image. Courtesy: PNNL.

Richland WA (SPX) May 06, 2005
Earth's surface has been getting brighter for more than a decade, a reversal from a dimming trend that may accelerate warming at the surface and unmask the full effect of greenhouse warming, according to an exhaustive new study of the solar energy that reaches land.

Ever since a report in the late 1980s uncovered a 4 to 6 percent decline of sunlight reaching the planet's surface over 30 years since 1960, atmospheric scientists have been trying out theories about why this would be and how it would relate to the greenhouse effect, the warming caused by the buildup of carbon dioxide and other gasses that trap heat in the atmosphere.

Meanwhile, a group led by Martin Wild at the Swiss Federal Institute of Technology in Zurich, home of the international Baseline Surface Radiation Network (BSRN) archive, had gone to work collecting surface measurements and crunching numbers.

"BSRN didn't get started until the early '90s and worked hard to update the earlier archive," said Charles N. Long, senior scientist at the Department of Energy's Pacific Northwest National Laboratory and co-author of a BSRN report in this week's issue (Friday, May 6) of the journal Science.

"When we looked at the more recent data, lo and behold, the trend went the other way," said Long, who conducted the work under the auspices of DOE's Atmospheric Radiation Measurement (ARM) program.

Data analysis capabilities developed by ARM research were crucial in the study, which reveals the planet's surface has brightened by about 4 percent the past decade.

The brightening trend is corroborated by other data, including satellite analyses that are the subject of another paper in this week's Science.

Sunlight that isn't absorbed or reflected by clouds as it plunges earthward will heat the surface. Because the atmosphere includes greenhouse gasses, solar warming and greenhouse warming are related.

"The atmosphere is heated from the bottom up, and more solar energy at the surface means we might finally see the increases in temperature that we expected to see with global greenhouse warming," Long said.

In fact, he said, many believe that we have already been seeing those effects in our most temperature-sensitive climates, with the melting of polar ice and high altitude glaciers.

The report's authors stopped short of attributing a cause to the cycle of surface dimming and brightening, but listed such suspects as changes in the number and composition of aerosols�liquid and solid particles suspended in air�and how aerosols affect the character of clouds.

Over the past decade, the ARM program has built a network of instrumentation sites to sample cloud characteristics and energy transfer in a variety of climates, from tropical to polar.

"The continuous, sophisticated data from these sites will be crucial for determining the causes," Long said.

Long also pointed out that 70 percent of the planet's surface is ocean, for which we have no long-term surface brightening or dimming measurements.

EARTH OBSERVATION

Polar-Orbiting NOAA-N To Launch May 11

Vandenberg AFB CA (SPX) May 03, 2005
The latest polar-orbiting operational environmental satellite developed by NASA for the National Oceanic and Atmospheric Administration (NOAA), called NOAA-N, is set to be launched on May 11, from Vandenberg Air Force Base, California, between 3:22:01 to 3:32:01 a.m. PDT.

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.