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.

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.

AR Impacting California

As Atmospheric River Reaches California, Scripps and NOAA Researchers Take Flight to Observe It

Precipitation due to a series of strong atmospheric rivers could provide partial relief to drought-stricken West

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

Scientists tracked the evolution of an “atmospheric river,” a narrow corridor of strong water vapor transport that can extend thousands of miles, as it made landfall in central California late last week. Atmospheric rivers 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 pattern expected to reach California during the Feb. 8 weekend had the potential to provide 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. The next several days could help change that, as a series of modest strength atmospheric rivers hit northern California. It is likely that over the next week these storms will produce as much precipitation in northern California as has fallen in the last four months. It could even triple the amount to date.”, said Marty Ralph.

Ralph heads a new center devoted to California’s special precipitation characteristics that has been established at Scripps Institution of Oceanography, UC San Diego. At the core of the Center for Western Water and Weather Extremes (CW3E) will be use of 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 5 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.

For this event, Ralph 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 air pressure, temperature, humidity, wind speed and direction to help better understand atmospheric rivers.

Aboard the aircraft, researchers released small parachuted devices, called dropsondes, across the atmospheric river over the Pacific Ocean. 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 is 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 are behind many of the pivotal precipitation events in California, including 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.

“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,” he said.

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.

For more information on the research flights, visit the California-Nevada Applications Program website.

Researchers find climate link to atmospheric river storms

Climate Oscillations Linked to Atmospheric River Events

November 25, 2013

Climate Oscillations

High and low-pressure anomalies on the map (red=high, blue=low) are typical of combined negative phases of the Arctic Oscillation and Pacific/North American teleconnection.

A new research study has found a link between large-scale climate features and the occurrences of atmospheric river events. The research team was led by Bin Guan from UCLA and NASA’s Jet Propulsion Laboratory. They discovered that the occurrence of a negative phase in both the Arctic Oscillation (AO) and the Pacific/North American (PNA) teleconnection is associated with an increase of atmospheric river events over California. The paper was recently published in the journal Water Resources Research and can be accessed here.

CW3E Director Addresses DWR/NWRI Drought Workshop

CW3E Director Addresses Drought Response Workshop

October 08, 2013

Dr. Ralph

High and low-pressure anomalies on the map (red=high, blue=low) are typical of combined negative phases of the Arctic Oscillation and Pacific/North American teleconnection.

Dr. Marty Ralph, Director of the Center for Western Weather and Water Extremes, briefed the Drought Response Workshop organized by the California Department of Water Resources (DWR) and the National Water Research Institute (NWRI) in Irvine, CA. The purpose of the workshop was to review and provide updates on drought planning, response and mitigation measures. Dr. Ralph introduced the new CW3E and discussed it’s mission as well as providing insight on the topic of drought.

A PDF document of Dr. Ralph’s presentations slides can be downloaded here.

A video of the talk is available here.

An overview of the conference and links to other presentations is available at the NWRI website.