Featured Research

from universities, journals, and other organizations

Global Land Precipitation Increases In 20th Century, NASA Scientists Find

Date:
November 19, 1997
Source:
National Aeronautics And Space Administration
Summary:
Global land precipitation has increased during the 20th century, especially at the mid and high latitudes, according to a paper published in the November 1997 issue of the Journal of Climate.

Global land precipitation has increased during the 20th century, especially at the mid and high latitudes, according to a paper published in the November 1997 issue of the Journal of Climate.

The paper, written by scientists Drs. Inez Fung, Anthony Del Genio, and Aiguo Dai, is based on a recalibrated compilation and analysis of data from 1900-1988 and confirms previous speculation that land precipitation is increasing. The new research shows a global land trend of a 2.4 mm per decade increase in annual precipitation amounts. Multiplied by almost nine decades, this means that there is about 22 mm more rain falling now each year than there was at the turn of the century -- rainfall as a global mean has risen by slightly more than two percent.

"Though much speculation remains as to the cause of this increase, further long-term study is needed to help ascertain the reasons for this change. The research does show, however, that both the spatial pattern and rate of precipitation increase are reminiscent of global climate model predictions of the atmosphere's response to an increase in greenhouse gas concentrations," said Dr. Anthony Del Genio, research scientist at NASA's Goddard Institute for Space Studies (GISS), New York City.

NASA scientists learned of this rise in precipitation from a new data set constructed at GISS. Scientists analyzed the data at face value but, in the process, used mathematical techniques to detect patterns of historical errors. Researchers developed new ways to objectively determine variations and remove ones that are not accurate. Finally, they performed a statistical test to determine the numerical confidence and came up with the revised database, which they believe shows the long term changes more precisely than previous analyses of the data.

"This database represents a potentially valuable resource for understanding the nature of land precipitation variations and their role in climate processes," said Dai, a researcher at GISS, a branch of NASA's Goddard Space Flight Center, Greenbelt, MD.

For example, the research analysis confirms the global patterns of the presence of an El Nino and also depicts the well-known Sahelian drought of the past few decades that has been a major influence over parts of Africa.

Through the construction of this historical database, researchers confirmed the occurrences of 24 droughts and five floods world-wide in the 20th century, though most took place in the tropics rather than middle latitudes.

Scientists have long held that precipitation is one of the most important aspects in Earth's climate system because of its impact on the global biosphere. In addition, precipitation limits the amount of water vapor in the atmosphere. Water vapor is the most important greenhouse gas and thus helps to determine Earth's surface temperature. The amount of water vapor in the atmosphere determines when and where clouds form.

"The latent heat released when water precipitates out of the atmosphere is the primary way in which the tropical ocean 'communicates' with the atmosphere and drives the tropical atmospheric circulation," said Del Genio.

Tracking precipitation and its relationship to global climate, however, has been difficult because the data have not been recorded into coordinated databases until recently. In addition, precipitation measurements vary widely across small geographic areas making it difficult to measure accurately. Through further study, NASA and researchers at GISS hope to create more accurate models from which conclusions about global rainfall can be drawn.

NASA also is due to launch this month the Tropical Rainfall Measuring Mission (TRMM), the first mission dedicated to measuring tropical and subtropical rainfall through microwave and visible infrared sensors. The TRMM mission includes the first spaceborne rain radar. Tropical rainfall comprises more than two-thirds of global rainfall. Data from the TRMM mission should greatly enhance researchers' understanding and prediction abilities of global climate change.

The ongoing research at GISS is funded through NASA's Mission to Planet Earth Enterprise, a long-term coordinated research effort to study the total Earth system and the effects of natural and human-induced changes on the global environment.

-end-

More information is available on the Internet at the following URL:

http://www.giss.nasa.gov/data/adai/


Story Source:

The above story is based on materials provided by National Aeronautics And Space Administration. Note: Materials may be edited for content and length.


Cite This Page:

National Aeronautics And Space Administration. "Global Land Precipitation Increases In 20th Century, NASA Scientists Find." ScienceDaily. ScienceDaily, 19 November 1997. <www.sciencedaily.com/releases/1997/11/971119071558.htm>.
National Aeronautics And Space Administration. (1997, November 19). Global Land Precipitation Increases In 20th Century, NASA Scientists Find. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/1997/11/971119071558.htm
National Aeronautics And Space Administration. "Global Land Precipitation Increases In 20th Century, NASA Scientists Find." ScienceDaily. www.sciencedaily.com/releases/1997/11/971119071558.htm (accessed July 28, 2014).

Share This




More Earth & Climate News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins