Jacques van Oene
April 21st 05, 10:19 PM
Gretchen Cook-Anderson/Dolores Beasley
Headquarters, Washington April 21, 2005
(Phone: 202/358-0836/1753)
RELEASE: 05-100
NASA STUDY FINDS SNOW MELT CAUSES LARGE OCEAN PLANT BLOOMS
A NASA funded study has found a decline in winter and spring snow cover
over Southwest Asia and the Himalayan mountain range is creating conditions
for more widespread blooms of ocean plants in the Arabian Sea.
The decrease in snow cover has led to greater differences in both
temperature and pressure systems between the Indian subcontinent and the
Arabian Sea. The pressure differences generate monsoon winds that mix the
ocean water in the Western Arabian Sea. This mixing leads to better growing
conditions for tiny, free-floating ocean plants called phytoplankton.
Lead author of the study is Joaquim Goes. He is a senior researcher at the
Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine. Goes and
colleagues used satellite observations of ocean color to show phytoplankton
concentrations in the Western Arabian Sea have increased by more than 350
percent over the past seven years. The study is in this week's SCIENCE
magazine
When winter and spring snow cover is low over Eurasia, the amount of solar
energy reflected back into the atmosphere is less. A decline in the amount
of snow cover means less of the sun's energy goes towards melting of snow
and evaporation of wet soil. As a result the land mass heats up more in
summer creating a larger temperature difference between the water of the
Arabian Sea and the Indian subcontinent landmass.
The temperature difference is responsible for a disparity in pressure over
land and sea, creating a low pressure system over the Indian subcontinent
and a high pressure system over the Arabian Sea. This difference in pressure
causes winds to blow from the Southwest Arabian Sea bringing annual rainfall
to the subcontinent from June to September. In the Western Arabian Sea,
these winds also cause upwelling of cooler nutrient-rich water, creating
ideal conditions for phytoplankton to bloom every year during summer.
Since 1997, a reduction in snow has led to wider temperature differences
between the land and ocean during summer. As a consequence, sea surface
winds over the Arabian Sea have strengthened leading to more intense
upwelling and more widespread blooms of phytoplankton along the coasts of
Somalia, Yemen and Oman.
According to Goes, while large blooms of phytoplankton can enhance
fisheries, exceptionally large blooms could be detrimental to the ecosystem.
Increases in phytoplankton amounts can lead to oxygen depletion in the water
column and eventually to a decline in fish populations.
The Arabian Sea hosts one of the world's largest pools of oxygen-poor water
at depths between 200 and 1,000 meters (656 to 3,281 feet). Since the
Arabian Sea lacks an opening to the north, the deeper waters are not well
ventilated. Also when organic matter produced by phytoplankton breaks down
and decomposes, more oxygen gets consumed in the process. An increase in
phytoplankton could therefore cause oxygen deficiencies in the Arabian Sea
to spread, leading to fish mortality.
Oxygen-depleted waters also provide the perfect environment for the growth
of a specialized group of bacteria called denitrifying bacteria. These
bacteria convert a nitrogen-based nutrient readily consumable by plants in
seawater, called nitrate, into forms of nitrogen that most plants cannot
use.
One form of nitrogen that plants cannot consume is nitrous oxide, also known
as laughing gas. In the atmosphere, nitrous oxide is 310 times more potent
as a greenhouse gas than carbon dioxide. Thus, as very large phytoplankton
blooms deplete more oxygen from the water, the creation of nitrous oxide in
the Arabian Sea could exacerbate climate change, Goes said.
For more information about this research on the Web, visit:
http://www.nasa.gov/vision/earth/lookingatearth/eurasian_melt.html
-end-
--
--------------
Jacques :-)
www.spacepatches.info
Headquarters, Washington April 21, 2005
(Phone: 202/358-0836/1753)
RELEASE: 05-100
NASA STUDY FINDS SNOW MELT CAUSES LARGE OCEAN PLANT BLOOMS
A NASA funded study has found a decline in winter and spring snow cover
over Southwest Asia and the Himalayan mountain range is creating conditions
for more widespread blooms of ocean plants in the Arabian Sea.
The decrease in snow cover has led to greater differences in both
temperature and pressure systems between the Indian subcontinent and the
Arabian Sea. The pressure differences generate monsoon winds that mix the
ocean water in the Western Arabian Sea. This mixing leads to better growing
conditions for tiny, free-floating ocean plants called phytoplankton.
Lead author of the study is Joaquim Goes. He is a senior researcher at the
Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine. Goes and
colleagues used satellite observations of ocean color to show phytoplankton
concentrations in the Western Arabian Sea have increased by more than 350
percent over the past seven years. The study is in this week's SCIENCE
magazine
When winter and spring snow cover is low over Eurasia, the amount of solar
energy reflected back into the atmosphere is less. A decline in the amount
of snow cover means less of the sun's energy goes towards melting of snow
and evaporation of wet soil. As a result the land mass heats up more in
summer creating a larger temperature difference between the water of the
Arabian Sea and the Indian subcontinent landmass.
The temperature difference is responsible for a disparity in pressure over
land and sea, creating a low pressure system over the Indian subcontinent
and a high pressure system over the Arabian Sea. This difference in pressure
causes winds to blow from the Southwest Arabian Sea bringing annual rainfall
to the subcontinent from June to September. In the Western Arabian Sea,
these winds also cause upwelling of cooler nutrient-rich water, creating
ideal conditions for phytoplankton to bloom every year during summer.
Since 1997, a reduction in snow has led to wider temperature differences
between the land and ocean during summer. As a consequence, sea surface
winds over the Arabian Sea have strengthened leading to more intense
upwelling and more widespread blooms of phytoplankton along the coasts of
Somalia, Yemen and Oman.
According to Goes, while large blooms of phytoplankton can enhance
fisheries, exceptionally large blooms could be detrimental to the ecosystem.
Increases in phytoplankton amounts can lead to oxygen depletion in the water
column and eventually to a decline in fish populations.
The Arabian Sea hosts one of the world's largest pools of oxygen-poor water
at depths between 200 and 1,000 meters (656 to 3,281 feet). Since the
Arabian Sea lacks an opening to the north, the deeper waters are not well
ventilated. Also when organic matter produced by phytoplankton breaks down
and decomposes, more oxygen gets consumed in the process. An increase in
phytoplankton could therefore cause oxygen deficiencies in the Arabian Sea
to spread, leading to fish mortality.
Oxygen-depleted waters also provide the perfect environment for the growth
of a specialized group of bacteria called denitrifying bacteria. These
bacteria convert a nitrogen-based nutrient readily consumable by plants in
seawater, called nitrate, into forms of nitrogen that most plants cannot
use.
One form of nitrogen that plants cannot consume is nitrous oxide, also known
as laughing gas. In the atmosphere, nitrous oxide is 310 times more potent
as a greenhouse gas than carbon dioxide. Thus, as very large phytoplankton
blooms deplete more oxygen from the water, the creation of nitrous oxide in
the Arabian Sea could exacerbate climate change, Goes said.
For more information about this research on the Web, visit:
http://www.nasa.gov/vision/earth/lookingatearth/eurasian_melt.html
-end-
--
--------------
Jacques :-)
www.spacepatches.info