ARs Play Role in Greenland Melt Episodes

Atmospheric Rivers Play Key Role in Rare Greenland Melt Episodes

Integrated Water Vapor (IWV) impacting Greenland on July 9, 2012 based on data from the 20th Century Reanalysis.

Researchers at NOAA’s Earth System Research Laboratory and the Center for Western Weather and Water Extremes here at Scripps have published a new article examining the processes responsible for the unusual melting episode in Greenland during the summer of 2012 when temperatures at the summit of Greenland rose above freezing for the first time since 1889. They found a number of climate factors were present in both 1889 and 2012 including strong atmospheric rivers transporting warm, moist air towards Greenland’s west coast. The research article was published in the Journal of Geophysical Research – Atmospheres.

A more in depth news story on this research can be found on the Scripps website.

A personal use copy of the article is available here.

Vision for future observations of extreme events in Western US

Vision for Future Observations of Extreme Precipitation and Flooding in the Western U.S.

A journal article entitled: A Vision for Future Observations for Western U.S. Extreme Precipitation and Flooding, by CW3E Director F. Martin Ralph and colleagues was recently published in the April 2014 issue of the Journal of Contemporary Water Research and Education

The paper describes how new technologies and paradigms using the most recent technological and scientific advances can be used to better monitor and predict extreme storms that lead to flooding in the Western U.S. The strategy is intended to add new technology to existing observational networks rather than replacement. The full journal article can be accessed here.

Schematic network of new sensors (land-based) to improve monitoring, prediction, and climate trend detection for hydrometeorological conditions that create extreme precipitation and flooding.

Atmospheric Rivers as Drought Busters

Atmospheric Rivers: Drought Busters

DroughtBuster_2010
Drought status in California before and after two atmospheric river events in January 2010 (middle panel shows precipitation from these systems over 20 inches in some areas).

Climate.gov recently highlighted CW3E researcher Mike Dettinger’s work looking at atmospheric rivers as drought busters (click here to see the climate.gov post). Mike’s article “Atmospheric Rivers as Drought Busters on the US West Coast” was published in December 2013 in the AMS Journal of Hydrometeorology (find a link to this article on the CW3E publications page or click here). Given the dry conditions that have persisted over the last few years causing severe to extreme drought over the US West this article has received well-deserved attention. The climate.gov piece highlights the impact of an atmospheric river storm from January of 2010. This image (shown above) illustrates the drought conditions before the storm (left panel), the amount of precipitation from the storm (middle panel – showing some areas had over 20 inches of precipitation!) and the drought conditions after the storm (right panel – showing the moderate and severe drought region greatly reduced).

Who rules California’s Russian River?

Who Rules California’s Russian River?

Lake Sonoma. Credit: Water Environment Research Foundation

Who has rightful claim to California’s Russian River? Federal law may protect the river habitat in the name of endangered fish, but on land, grapevines are king. In the first of a two-part series, NOAA’s Caitlyn Kennedy describes how NOAA scientists are working with partners at other agencies and universities to help find compromise amid local tensions over water supplies.

Part 1 describes scientists’ efforts to understand and predict not just the river on land, but its counterpart in the sky—a river that delivers extreme, sometimes drought-busting storms into the heart of California’s wine country. Sometimes these storms can be a blessing. And at other times, a curse.

Part 1 is now available at: http://www.climate.gov/news-features/features/who-rules-californias-russian-river

Part 2 will explore how better forecasting of and strategies for coping with extreme events could lessen water conflicts along the Russian River.

Likelihood of Drought Ending, updated

Drought Recovery by end of Water Year?

The most recent figures can be found on Mike Dettinger’s web page.

Drought Recovery Odds

Updated March 21, 2014

Researcher Mike Dettinger has updated his analysis examining the likelihood of the California drought ending by the end of the current water year on Sept 30, 2014. This new analysis utilizes the just released February precipitation totals for California’s climatic divisions as well as best guess estimates for March 2014 precipitation. Visit the CW3E Drought Info Page to see updated projections for all seven of California’s climatic divisions.

Drought Recovery Odds


February 12, 2014

CW3E researcher Mike Dettinger was interested in knowing the likelihood of California recovering from the drought by the end of the current water year on Sept 30, 2014. The method he came up with starts with the precipitation deficit from last water year (Oct 2012 – Sept 2013). Observed precipitation for Oct 2013 thru Jan 2014 was used to determine what has been added to this previous water year deficit, depicted in the above figure by the black squares. Here negative precipitation refers to the carryover deficit from the period extending back to October 2012.

Projections into the future of cumulative precipitation since Oct 2012 were computed by adding observed monthly precipitation from each year in the historical record, 1931-2013, or a total of 83 projections. For each future month (Feb-Sep 2014) the red dots in the above figure represent each of the 83 projections.

The example shown above is for the Sacramento Drainage region (CA Climate Division 2). For this region, only 2 of the 83 projections make it above the 75%-tile level by the end of Sept 2014. None of the projections show the 24-month cumulative precipitation reaching “normal” levels by the end of this water year.

Visit the CW3E Drought Info Page to see projections for all seven of California’s climatic divisions.

Dust storms: enhancing California’s precipitation

Dust Storms: enhancing California’s precipitation

Dust, as shown by orange colors, in a storm approaching California on 24 February 2014. (NASA Earth Observing System Data and Information System)

As CW3E continues to investigate rainfall over California from Atmospheric River storms, other researchers examine the same storms to evaluate the role of dust in enhancing precipitation amounts. A recent KQED story examines the work of Dr. Kim Prather (UCSD; atmospheric chemist). Dr. Prather evaluates the role of dust from storms over Africa and Asia that reach the California coast in 7-10 days. The high altitude particles have been found to increase the amount of rain and snowfall when they coincide with approaching coastal storms. See more on the story (including an audio piece) at: http://blogs.kqed.org/science/audio/drought-distant-dust-storms-matter-to-california-rainfall/

Scripps Researchers Take Flight

Scripps and NOAA Researchers Take Flight to Observe Atmospheric River


IWV Feb 5-10, 2014

Integrated Water Vapor GFS Analysis Feb 5-10, 2014.

Researchers from Scripps Institution of Oceanography at UC San Diego, and NOAA are taking part in research flights to observe a distinctive type of storm system that has historically provided significant precipitation to California.

Scientists tracked the evolution of “atmospheric rivers,” narrow corridors of strong water vapor transport that can extend thousands of miles, as they made landfall in central California in early February. Atmospheric rivers (ARs), identified by researchers only in recent decades, can provide beneficial water supply and snowpack to the West Coast as well as create conditions for dangerous floods that affect lives and property. NOAA, Scripps, USGS, and other agency/institution researchers, working with water managers for the state, Sonoma County, and elsewhere, are studying them with the goal of providing better information for earlier and more accurate extreme weather forecasts. Scripps and USGS scientists are also looking at how atmospheric rivers may serve as “drought busters” and how climate change may affect atmospheric rivers in future decades.

Scripps researchers said that the February storms provided some relief, but would likely not reverse the dangerous drought conditions throughout California and the West that have built up over the last three years.

“Part of the reason for the drought has been the absence of atmospheric river storms hitting the region over the last year,” said Scripps climate researcher Marty Ralph. “From Feb. 7-10, a series of modest strength ARs hit Northern California, including near San Francisco and the northern Sierra where AR conditions stalled for up to 48 hours. These conditions created up to 12-15 inches of rain in three days, including in areas hit by the drought. This was more than double the precipitation in Northern California that had fallen in the first four months of the normal wet season. Nonetheless, the extreme drought has produced such a deficit in water that the soils absorbed much of the precipitation and rivers quickly receded to levels that are again well below normal, even though they reached fairly high levels during the storm.”

Ralph heads the Center for Western Water and Weather Extremes (CW3E), a new center established at Scripps Oceanography that is devoted to California’s special precipitation characteristics. At the core of the center will be a unique advanced network of monitoring stations throughout the state to help industries and 38 million California residents understand phenomena that affect the economy and everyday life in myriad ways.

The network, built over the last five years by NOAA and Scripps through support from California’s Department of Water Resources, will initially contain four atmospheric river observatories, monitoring stations located in Northern and central California that measure amounts of water vapor in the atmosphere and other climate variables.

“NOAA is very interested in improving our forecasts of extreme weather events, and atmospheric rivers rank with hurricanes as a major issue,” said Chris Fairall, chief of the Weather and Climate Physics branch of NOAA’s Earth System Research Laboratory in Boulder, Colo. “The West Coast relies on them for water, but it really is like trying to drink from the proverbial firehose. This new research collaboration on atmospheric rivers with Scripps and UC San Diego is a big step in attacking the problem.”

For this event, Ralph, Fairall, and colleagues gathered data aboard a NOAA Gulfstream IV aircraft that began flying over the Pacific Ocean off the U.S. West Coast on Feb. 7. During the flights, researchers measured several atmospheric properties at several locations along and across the atmospheric river corridor to better understand key processes, such as where the water vapor sources are and how they are sustained by storm dynamics.

Aboard the aircraft, researchers released small parachuted devices, called dropsondes, across the atmospheric river over the Pacific Ocean. As they descend, the dropsondes measure atmospheric conditions, such as pressure, temperature, humidity, wind speed and direction, and transmit the information back to the aircraft where a flight scientist uses it to guide the mission. After the dropsonde data are analyzed and processed, the information will be put into a standard format established by the World Meteorological Organization and provided to NOAA’s National Hurricane Center for inclusion in global and local-scale weather prediction models.

Mike Dettinger, a CW3E team member and research hydrologist with Scripps and the U.S. Geological Survey, noted that atmospheric rivers provide 30 to 50 percent of the precipitation in California and are behind 80 percent of the floodplain inundations along parts of the Central Valley where those inundations are a necessary part of ecosystem food webs and fish nurseries. They figure prominently in the ending of California droughts but also in taxing Northern California levees and other components of the state’s water delivery infrastructure.

“Thus, better understanding of how atmospheric rivers work and how they may change in the future is critical to better water, floods, and ecosystem management and to plans for adapting to future climate changes,” Dettinger said.

Jay Jasperse, chief engineer for the Sonoma County Water Agency, which provides water to 600,000 people and many agricultural users, said of the February storms, “although this AR may not be the strongest ever, it is certainly the most welcome.”

Results from this study will help guide atmospheric river research for the upcoming CalWater 2 experiment, which begins in 2015 and will use land-based stations and a research ship as well as multiple aircraft.

CW3E welcomes Dr. Ryan Spackman

CW3E welcomes Dr. Ryan Spackman

February 12, 2014

CW3E is pleased to welcome Dr. Ryan Spackman! Ryan, an atmospheric chemist, will play a critical role bridging CW3E’s dynamics-focused capabilities with chemistry prowess. As deputy principal investigator for NASA Earth Venture and as a member of the CalWater 2 Core Scientific Steering Group, Ryan brings extensive expertise with airborne science campaign planning, execution and delivery of results. Ryan has a passion for observing the components of the water budget and using this data to evaluate weather and climate models. Graduating with a PhD from Harvard in 2004, Ryan continues to work with NOAA’s Earth System Research Laboratory and Science and Technology Corporation. Ryan’s abilities, enthusiasm and energy are superb additions to the CW3E group.

Likelihood of Drought Ending

Drought Recovery by end of Water Year?

New updates to these figures taking into account February rains, and estimates of rains thru mid March, are available.

Please see updated information including a full set of updated figures on Mike Dettinger’s page and on post from 21 March 2014

February 12, 2014

Drought Recovery Odds

CW3E researcher Mike Dettinger was interested in knowing the likelihood of California recovering from the drought by the end of the current water year on Sept 30, 2014. The method he came up with starts with the precipitation deficit from last water year (Oct 2012 – Sept 2013). Observed precipitation for Oct 2013 thru Jan 2014 was used to determine what has been added to this previous water year deficit, depicted in the above figure by the black squares. Here negative precipitation refers to the carryover deficit from the period extending back to October 2012.

Projections into the future of cumulative precipitation since Oct 2012 were computed by adding observed monthly precipitation from each year in the historical record, 1931-2013, or a total of 83 projections. For each future month (Feb-Sep 2014) the red dots in the above figure represent each of the 83 projections.

The example shown above is for the Sacramento Drainage region (CA Climate Division 2). For this region, only 2 of the 83 projections make it above the 75%-tile level by the end of Sept 2014. None of the projections show the 24-month cumulative precipitation reaching “normal” levels by the end of this water year.

New updates to these figures taking into account February rains, and estimates of rains thru mid March, are available here.

Visit the CW3E Drought Info Page to see projections for all seven of California’s climatic divisions.