Atmospheric rivers research: WISPAR campaign by NASA's Global Hawk is intended to study the concentrated streams of tropical moisture that sometimes get connected with cold fronts and winter storms approaching the U.S. West Coast -- sometimes called the pineapple express, since they often originate near Hawaii -- which can result in very intense rain events

Airborne Sensor to Study 'Rivers in the Sky'

ScienceDaily, February 11, 2011 — They're called atmospheric rivers -- narrow regions in Earth's atmosphere that transport enormous amounts of water vapor across the Pacific or other regions. Aptly nicknamed "rivers in the sky," they can transport enough water vapor in one day, on average, to flood an area the size of Maryland 0.3 meters (1 foot) deep, or about seven times the average daily flow of water from the Mississippi River into the Gulf of Mexico. The phenomenon was the subject of a recent major emergency preparedness scenario led by the U.S. Geological Survey, "ARkStorm," which focused on the possibility of a series of strong atmospheric rivers striking California -- a scenario of flooding, wind and mudslides the USGS said could cause damages exceeding those of Hurricane Katrina in 2005.

While atmospheric rivers are responsible for great quantities of rain that can produce flooding, they also contribute to beneficial increases in snowpack. A series of atmospheric rivers fueled the strong winter storms that battered the U.S. West Coast from western Washington to Southern California from December 10 to December 22, 2010, producing 28-64 centimeters (11-25 inches) of rain in certain areas. The atmospheric rivers also contributed to the snowpack in the Sierras, which received 75% of its annual snow by December 22, 2010, the first full day of winter.

To improve our understanding of how atmospheric rivers form and behave and evaluate the operational use of unmanned aircraft for investigating these phenomena, NASA scientists, aircraft and sensors will participate in a National Oceanic and Atmospheric Administration-led airborne field campaign slated to begin Feb. 11.

Called Winter Storms and Pacific Atmospheric Rivers, or WISPAR, the field campaign, which continues through the end of February 2011, is designed to demonstrate new technology, contribute to our understanding of atmospheric rivers and assist NOAA in potentially conducting offshore monitoring of atmospheric rivers to aid in future weather predictions.

A NASA Global Hawk unmanned aircraft operated out of NASA's Dryden Flight Research Center in Southern California is scheduled to depart Dryden Friday morning, February 11, 2011, on the campaign's first science flight. The 24-hour flight will study an atmospheric river currently developing in the Pacific Ocean off Hawaii that appears as though it will impact the Oregon-California coast this weekend. Aboard the Global Hawk will be new weather reconnaissance devices called dropsondes developed by the National Center for Atmospheric Research that will take temperature, wind and other readings as they descend through an atmospheric river. Also aboard will be an advanced water vapor sensor -- the High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer, or HAMSR -- created by NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The remote-sensing HAMSR instrument analyzes the heat radiation emitted by oxygen and water molecules in the atmosphere to determine their density and temperature. The instrument operates at microwave frequencies that can penetrate clouds, enabling it to determine temperature, humidity and cloud structure under all weather conditions. This capability is critical for studying atmospheric processes associated with bad weather, like the conditions present during atmospheric river events.

HAMSR Principal Investigator Bjorn Lambrigtsen of JPL says the instrument -- the most accurate and sensitive of its kind in the world -- will help scientists better understand these unique weather phenomena.

"The WISPAR campaign is intended to study the concentrated streams of tropical moisture that sometimes get connected with cold fronts and winter storms approaching the U.S. West Coast -- sometimes called the pineapple express, since they often originate near Hawaii -- which can result in very intense rain events," Lambrigtsen said. "HAMSR, flying on NASA's unpiloted Global Hawk well above the weather but close enough to get a much more detailed picture than is possible from a satellite, will be used to map out this phenomenon and answer scientific questions about the formation and structure of these systems."

NASA's Global Hawk is an ideal platform from which to conduct WISPAR science because it is able to fly long distances, stay aloft for more than 24 hours, and travel at high and low altitudes that could be dangerous for humans. Lambrigtsen will be at Dryden in the Global Hawk Operations Center during the flights, using data from the sensor and other information to adjust the Global Hawk's flight track, as necessary, to optimize the sampling of the atmospheric rivers.

Lambrigtsen said the public can monitor the progress of the WISPAR science flights in real time on a WISPAR version of JPL's hurricane portal website athttp://winterscience.jpl.nasa.gov/WISPAR2011/ . The site will display the most recent satellite images, the Global Hawk flight track and a real-time subset of HAMSR data.

For more information about WISPAR, visit: 

http://www.noaanews.noaa.gov/stories2011/20110210_atmosphericrivers.html. 

For more on HAMSR, see:http://microwavescience.jpl.nasa.gov/instruments/hamsr/

http://www.sciencedaily.com/releases/2011/02/110211202025.htm

Jeff Masters: The ARkStorm: California's coming great deluge

The ARkStorm: California's coming great deluge

Posted by: JeffMasters, wunderblog, 4:04 PM GMT on January 28, 2011

For thirty days and thirty nights the rain fell in unending torrents. By the end of the biblical deluge, rivers of water ten feet deep flowed through the streets of Sacramento, and an astounding 29.28 inches of rain had fallen on San Francisco. According to wunderground's weather historian, Christopher C. Burt, in the Sierras, the moist flow of air from Hawaii -- often called an "atmospheric river" or the "Pineapple Express" -- hit the steeply sloping mountainsides, rose upwards, expanding and cooling. Truly prodigious rains resulted, with the mining town of Sonora receiving 8.5 feet of rain over a 2-month period. The resulting floods inundated California's Central Valley with a lake 300 miles long and 20 miles wide.

The above event occurred in January 1862, and similar extreme rain events have deluged in California seven times in the past 2,000 years--about once every 300 years. Great storms like the flood of 1862 will happen again. If the planet continues to warm, as expected, the odds of such an event will at least double by 2100, due to the extra moisture increased evaporation from the oceans will add to the air. A group of scientists, emergency managers, and policy makers gathered in Sacramento, California, earlier this month to discuss how the state might respond to a repeat of the 1862 rain event--the ARkStorm Scenario. The "AR" stands for "Atmospheric River", the "k" for 1,000 (like a 1-in-1000 year event), and of course "ARkStorm" is meant to summon visions of biblical-scale deluge, similar to the great flood of 1862. The team's final report envisions the most expensive disaster in world history, with direct damages and loss of economic activity amounting to $725 billion.

"Atmospheric Rivers" was a term coined in the 1990s to describe plumes of moisture that ride up out of the subtropics into the mid-latitudes along the axis of a cold front. Traditional water vapor satellite imagery does not show these plumes very well, and it was only when microwave satellite imagery from polar orbiting satellites became available in the late 1990s that the full importance of these Atmospheric Rivers came to be revealed. Atmospheric Rivers account for a significant portion of California's cold season rainfall and snowfall, and an entire session was devoted to them at the December 2010 American Geophysical Union (AGU) meeting in San Francisco, the world's largest Earth Science meeting.


Figure 1. The total amount of rainfall one could get if all the moisture in the air were condensed and fell out as rain is called the Total Precipitable Water (TPW). Here, TPW values from microwave satellite measurements are plotted, and show a plume of very moist air connecting the subtropics near Hawaii with Southern California. TPW vales in excess of 20 mm (about 0.8 inches, blue and warmer colors) are "Atmospheric Rivers," and are often associated with heavy rainfall events capable of causing flooding. This Atmospheric River occurred on December 21, 2010, and brought very heavy flooding rains to Southern California. Image credit: University of Wisconsin CIMSS.

California's Delta Region levees at high risk of failure
Much of Central California's water supply and agricultural areas are protected by an antiquated and poorly maintained set of levees along the Sacramento and San Joaquin Rivers that are in serious danger of failure during an extreme flood or major earthquake. The 1,600 miles of levees protect 500,000 people, 2 million acres of farmland, and structures worth $47 billion. Of particular concern is the delta at the confluence of California's Sacramento and San Joaquin rivers, about 80 miles inland from San Francisco Bay. The Delta Region receives runoff from more than 40% of California, and is the hub of California's water supply system, supplying water to 25 million people and 3 million acres of farmland. Key transportation and communication lines cross the region. The Delta Region is home to dozens of islands with highly productive farms that have subsided to elevations as much as 25 feet below sea level. Jeffrey Mount, director of the Center for Integrated Watershed Science and Management at the University of California at Davis, said in a recent interview with MSNBC, "The chances of a catastrophic flood occurring in the Sacramento-San Joaquin Delta sometime in the next 50 years are about two out of three." He called Sacramento, which is only protected to a 1-in-80 year flood by its levees, "the most at-risk large metropolitan area in the country, with less than half the protection that New Orleans had. It is at extreme risk due to levee failure and subsidence."" The most serious catastrophe for the levees in the Delta Region would be a major earthquake occurring during the dry season. Such a quake would allow salt water to intrude from San Francisco Bay, shutting off the fresh water supply for millions of Californians for months. Collapse of the levees during the wet season would be less devastating, as water pressure from the relatively high flow rates of the Sacramento and San Joaquin Rivers would keep salt water from intruding into the Delta Region. There are no good solutions to California's Delta Region water vulnerabilities, but a new $10 billion dollar canal that would route fresh water around the region is being proposed as a possible way Califoria could avoid losing its fresh water supply if a catatrophic failure of the Delta Region levees allowed salt water intrusion to occur.

A 2009 study by the California Department of Water Resources concluded:
The Delta Region as it exists today is unsustainable. Seismic risk, high water conditions, sea level rise and land subsidence threaten levee integrity. A seismic event is the single greatest risk to levee integrity in the Delta Region. If a major earthquake occurs, levees would fail and as many as 20 islands could be flooded simultaneously. This would result in economic costs and impacts of $15 billion or more. While earthquakes pose the greatest risk to Delta Region levees, winter storms and related high water conditions are the most common cause of levee failures in the region. Under business-as-usual practices, high water conditions could cause about 140 levee failures in the Delta over the next 100 years. Multiple island failures caused by high water would but could still be extensive and could cause approximately $8 billion or more in economic costs and impacts. Dry-weather levee failures [also called sunny-day events] unrelated to earthquakes, such as from slumping or seepage, will continue to occur in the Delta about once every seven years. Costs to repair a single island flooded as the result of a dry-weather levee failure are expected to exceed $50 million. The risk of flooding in the Delta Region will only increase with time if current management practices are not changed. By the year 2100, Delta levee failure risks due to high water conditions will increase by 800%. The risk of levee failure from a major earthquake is projected to increase by 93% during the same period.

The ARkStorm scenario and Great Flood of 1862 are discussed in much more detail by weather historian Christopher C. Burt in his latest post.


Figure 2. Levee failure on the Upper Jones Tract in the Delta Region on June 4, 2004. Image credit: California Department of Water Resources. A 1997 flood in the Delta Region did $510 million damage, damaged or destroyed 32,000 homes and businesses, and left 120,000 homeless.

Link:  http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1736

NYT: If California's earthquakes weren’t enough, enter the ‘Superstorm’ carried by atmospheric rivers

If California's earthquakes weren’t enough, enter the ‘Superstorm’ carried by atmospheric rivers

by Felicity Barringer, New York Times, January 15, 2011


SACRAMENTO — California faces the risk not just of devastating earthquakes but also of a catastrophic storm that could tear at the coasts, inundate the Central Valley and cause four to five times as much economic damage as a large quake, scientists and emergency planners warn.


The potential for such a storm was described at a conference of federal and California officials that ended Friday. Combining advanced flood mapping and atmospheric projections with data on California’s geologic flood history, over 100 scientists calculated the probable consequences of a “superstorm” carrying tropical moisture from the South Pacific and dropping up to 10 feet of rain across the state.

“Floods are as much a part of our lives in California as earthquakes are,” said Lucy Jones, the chief scientist for the United States Geological Survey’s multi-hazards initiative, adding, “We are probably not going to be able to handle the biggest ones.”

The geological survey estimates that such a storm could cause up to $300 billion in damage. The scientists’ models estimate that almost one-fourth of the houses in California could experience some flood damage from one.

The conference was convened by the geological survey, the Federal Emergency Management Agency and the California Emergency Management Agency to help disaster-response planners draft new strategies to limit the storms’ impact.

Climate scientists have for years noted that the rising temperature of the earth’s atmosphere increases the amount of energy it stores, making more violent and extreme weather events more likely.

Californians have learned to expect earthquakes the way Floridians expect hurricanes. (A minor earthquake, with a preliminary magnitude of 4.1, rattled windows in the southern part of the San Francisco Bay area about a week ago.)

The existing engineering systems that dispose of floodwater are so efficient that the effects of moderate storms often go unnoticed, Dr. Jones said. So while many Californians know whether they live or work close to an earthquake-prone fault and what to do should there be a serious quake, few realize that the state could be hit by storms that at their worst could rival the largest hurricanes that devastate the Gulf Coast and the southeastern Atlantic Seaboard.

Yet vast floods have also been documented, both through tree-ring data and more modern historical records. Marcia K. McNutt, the director of the geological survey, said that 150 years ago, over a few weeks in the winter of 1861-1862, enough rain fell to inundate a stretch of the Central Valley 300 miles long and 20 miles wide, from north of Sacramento south to Bakersfield, near the eastern desert.

The storms lasted 45 days, creating lakes in parts of the Mojave Desert and, according to a survey account, “turning the Sacramento Valley into an inland sea, forcing the state capital to be moved from Sacramento to San Francisco for a time, and requiring Gov. Leland Stanford to take a rowboat to his inauguration.”

Just like a major earthquake, a superstorm could be a severe blow to the state’s agriculture and to the water-supply system that now diverts water from the north to Southern California.

Dr. Jones said in an interview that improved satellite imagery available in recent years allowed scientists to clearly identify what they call “atmospheric rivers” — moisture-filled air currents up to 200 miles wide and 2,000 miles long, which flow from tropical regions of the Pacific Ocean to the West Coast.

The West Coast winter weather systems popularly known as the Pineapple Express, air currents carrying moisture from the Hawaiian Islands are just one moderate subset of these rivers, Dr. Jones said. The abbreviation for atmospheric river, A.R., gave the geological survey the root of its name for these major weather events, which they call ARk storms.

Link:  http://www.nytimes.com/2011/01/16/science/earth/16flood.html?ref=earth

The First Atmospheric River of the Season by Cliff Mass

The First Atmospheric River of the Season

by Cliff Mass, Cliff Mass Weather Blog, September 23, 2010

Some of the most important wintertime weather features of our region are the plumes of moisture that stream northeastward out of the tropics and subtropics. In the discipline these plumes are often called "atmospheric rivers" and the atmospheric river that is often discussed in the media is the "pineapple express." This weekend the first major atmospheric river of the season will strike our region, specifically central and northern Vancouver Island and adjacent portions of British Columbia.

Here is a recent computer forecast of the amount of water vapor in the atmosphere (the fancy name is "column-integrated water vapor"-- throw that around and you will impress your friends!) for 11 AM on Saturday. The blues are high values -- see the atmospheric river?



The plumes of atmospheric moisture associated with these rivers is usually associated with warm temperatures -- in fact it HAS to be that way, because only warm air can hold large amounts of water vapor. When this warm juicy air strikes our mountains it is forced to rise --the result being large amounts of precipitation. Want to see what the models are going for? Here is the forecast 24-h rainfall ending 5 PM on Sunday. The reds are FIVE TO TEN INCHES OF RAIN! There is even a white area, where more than 10 inches is predicted.


Fortunately for us, the U.S. side of the border will only get a weakened share of this wet bounty -- after a generally dry Saturday the front that is associated with this precipitation will move through rapidly, with only modest showers over western Washington.

Do we expect a lot of strong atmospheric rivers this year? Will one hit the weakened Howard Hanson Dam? What I can tell you is that the upcoming winter will be a La Nina period and generally the strongest atmospheric rivers and floods are during neutral years (neither La Nina or El Nino). So although we expect this fall and winter to be wetter than normal (due to La Nina), there is less chance for a mega-rain/flooding event. Yes, it could happen, but it is less likely.

Link:  http://cliffmass.blogspot.com/2010/09/first-atmospheric-river-of-season.html

Atmospheric River Slams Northern California, October 2010

Atmospheric River Slams Northern California

Released: 10/15/2009 4:59:26 PM

Contact Information:  U.S. Department of the Interior, U.S. Geological Survey, Office of Communication, 119 National Center, Reston, VA 20192, U.S.A.

Dale  Cox Phone: 916-278-3033

As people in northern California begin to assess damage from the high winds and heavy rain of October 13 and 14, 2010, they may wonder what hit them.  The answer, according to Dave Reynolds, meteorologist-in-charge at NOAA's National Weather Service forecast office in Monterey, was an "atmospheric river," the meteorological phenomenon that draws water vapor from the Pacific Ocean near the equator and transports it to the U.S. West Coast with firehose-like ferocity.

Atmospheric Rivers, or “ARs,” are technically associated with cyclones,” says Dr. Marty Ralph, Research Meteorologist at NOAA's Earth System Research Laboratory in Boulder. "Although these cyclones are not of the iconic circular pattern commonly associated with hurricanes, they do include hurricane-strength winds and can yield rainfall comparable to that of hurricanes.  The ARs in these cyclones are regions where low-altitude winds transport huge amounts of water vapor up against the mountains, which wrings out extreme rainfall." The AR this week produced a remarkable 21 inches of rain in just one day in the mountains near Big Sur, and winds that exceeded hurricane force.

While the atmospheric river that hit central California on October 13 and 14 was large, breaking some daily rainfall records and streamflow records for this time of year on several California creeks and rivers, including the Salinas River, the Russian River, and the Merced River, according to USGS Research Hydrologist, Dr. Michael Dettinger, in many cases, the results can be much larger, especially later in the winter. Nonetheless, this AR would have been notably long and strong any time of year.

For weather experts, storms this large always bring to mind the historically massive storms that impacted both northern and southern California in 1861 and 1862, flooding the Central Valley of California, obliterating at least one community in southern California, and causing the state capital to me moved from Sacramento to San Francisco.  According to scientists, storms of this magnitude will eventually happen again.

To address storms of this magnitude and help prepare emergency responders and resource managers, the USGS Multi-Hazards Demonstration Project, creators of the ShakeOut Earthquake Scenario, are working with researchers like Ralph, Dettinger and Reynolds to construct a massive, though scientifically plausible, hypothetical storm scenario, called "ARkStorm."

The ArkStorm scenario has adapted data and information from recent U.S. West Coast storms to simulate the type of storms that impacted northern and southern California in 1861 and 1862.  With the atmospheric scenario completed, experts are now examining in detail the probability, cost, and consequences of floods, landslides, coastal erosion and inundation; debris flows; environmental effects; agricultural loss; and possible physical damage such as bridge scour, road closures, dam failure, property loss, and levee-system collapse. The ARkStorm scenario is scheduled to be the basis of statewide emergency response drill in 2011.

"There is no specific scale for categorizing atmospheric rivers,” said Dale Cox, Project Manager of the USGS Multi-Hazards Demonstration Project.  “We tend to call West Coast storms by the year they occurred, like 1969, 1986 and 1997.  ARkStorm represent an atmospheric river (AR) with a value of 1,000 on a scale of atmospheric rivers yet to be determined by atmospheric scientists."

In addition to the ARkStorm scenario, the USGS Multi-Hazards Demonstration Project led the creation of the ShakeOut Earthquake Scenario that became the basis of the Great ShakeOut earthquake preparedness drill last fall. They are also responsible for the multi-hazards, multi-agency, and multi-scientific discipline approach behind the recent debris flow assessment and warning system being used at the Station Fire in southern California.

"There was a unnerving convergence of coincidence, danger and irony as this atmospheric river roiled into California, threatening to cause massive debris flows, on the day of the annual Great California ShakeOut, " said Lucy Jones, Chief Scientist of the USGS Multi-Hazards Demonstration Project, who's home is directly below the Station Fire burn perimeter. "We just dodged a bullet."

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