IARC 2016

The First International Conference on Atmospheric Rivers (IARC) is Being Hosted by the Center for Wester Weather and Water Extremes (CW3E) at the Scripps Seaside Forum from 8-11 August 2016

August 8, 2016

IARC is part of a multi-year effort led by CW3E’s Director F. Martin Ralph, Mike Dettinger of USGS and David Lavers of ECMWF to foster collaboration and exchange of ideas on atmospheric rivers (AR).

  • The first event was held in June 2015 and brought together about 30 key individuals in a workshop, with a special emphasis on identifying the relationships between ARs, warm conveyor belts, and tropical moisture exports, all phenomena involving horizontal water vapor transport. A brief workshop synopsis is available in EOS (Dettinger et al. 2015) and here. Two main directions emerged:
    • 1) agreement that it was time to develop a comprehensive monograph on ARs, and
    • 2) an atmospheric river focused conference should be organized.
  • The second event in this 3-year effort is the 2016 IARC conference held from 8-11 August (described below; agenda).
  • The third event is a summer colloquium intended for summer 2017 at Scripps. It is intended to bring together at Scripps authors of the AR Monograph Book Chapters and graduate students from around the world for roughly 3 weeks of lectures and mentored mini-research efforts.

Woven through this series of events over 3 years is the development of the AR Monograph, which has been funded by a grant, including publication by University of California Press. IARC brings together most of the Chapter authors, at a point in the writing where new ideas garnered during the conference can be incorporated into the Monograph. The goal is then to have the Monograph finalized and in print for the AR Summer Colloquium. A technical editor, Lauren Muscatine (and her experienced team from UC Davis), is supporting preparation of the Monograph.

IARC received 75 abstracts from people around the world studying ARs, their impacts and applications of AR information to decision making. Submissions represent work on 6 continents plus Greenland. It has been planned by an international steering committee of experts on the subject. 90 people have registered for the conference, which will include several invited presentations, oral sessions, a poster session, panels on “applications to decision making,” “converging on a definition of atmospheric rivers” and on “future directions.” Breakout sessions will be held on “AR Forecasting,” “AR Book Chapters” and on “ARs in future climates and subseasonal to seasonal prediction.”

Sessions are organized around the following themes, which represent sections in the AR Monograph:

  • AR Applications
  • Global and Regional Perspectives
  • Observing and detecting ARs
  • Impacts of ARs
  • Theory, Structure and Processes
  • Modeling methodologies

Contact: F. Martin Ralph (mralph@ucsd.edu)

Lake Mendocino Forecast-Informed Reservoir Operations (FIRO) Workshop Summary

Lake Mendocino Forecast-Informed Reservoir Operations (FIRO) Workshop Summary

July 5, 2016

Experts from multiple disciplines and organizations came together for the third annual FIRO workshop, which was held at UC San Diego/Scripps Institution of Oceanography (SIO) from 27-29 June 2016. This workshop was hosted jointly by the Sonoma County Water Agency (SCWA) and SIO’s Center for Western Weather and Water Extremes (CW3E). It was organized by the FIRO Steering Committee, co-chaired by CW3E’s Marty Ralph and SCWA’s Jay Jasperse. There were a total of 52 attendees from organizations including the US Army Corps of Engineers (USACE), California Department of Water Resources (CA DWR), National Oceanic and Atmospheric Administration (NOAA), US Geological Survey (USGS), US Bureau of Reclamation (USBR), SCWA and CW3E.

During the workshop, participants shared recent updates on FIRO activities, discussed reservoir conditions during water year 2016, summarized progress toward goals identified in the FIRO Workplan and identified issues to address regarding development of the Lake Mendocino FIRO “Preliminary Viability Assessment.” Progress was summarized on defining FIRO information requirements (e.g., forecast parameters and lead times), assessing current forecast skill, exploring the origins of forecast errors, advances in atmospheric river science, results of preliminary estimates of FIRO implications on Lake Mendocino water supply, and discussion of potential additional reservoirs for which FIRO may hold promise. Individual task groups (Preliminary Viability Assessment, Science, and Communications/Outreach) conducted break-out sessions in order to discuss progress and next steps towards meeting project goals (see photos below). In addition, the 11-member Lake Mendocino FIRO Steering Committee met afterward to review the workshop outcomes and plans. In short, the initial goals of year-1 of the 5-year FIRO Workplan are on track to be met, including development of the Preliminary Viability Assessment. Longer-term actions supporting the Full Viability Assessment are beginning and transferability is being discussed.

Lake Mendocino FIRO is summarized at http://cw3e.ucsd.edu/firo/.

Contacts: F. Martin Ralph (CW3E Director; mralph@ucsd.edu) and J. Jasperse (SCWA Chief Engineer; Jay.Jasperse@scwa.ca.gov)

CW3E represented in recent policy and program meetings

CW3E Represented in Recent Policy and Program Meetings

June 8, 2017

During the last few weeks CW3E’s perspectives have been highlighted at three science policy-oriented meetings. The connection between CW3E’s scientific activities, practical applications and water policy implications is a common theme among them. The meetings and a brief synopsis are provided below:

1) AGU Congressional briefing on role of basic Geoscience in American Security May 2016

AGU invited three speakers to a Congressional briefing they organized to communicate to staff supporting a number of elected officials and policy committees. The goal was to make the connection between basic science advances (and the funding that has supported them), and benefits to American Security. CW3E’s Director, Dr. Ralph, represented the role of basic geoscience research in advancing water security in the Western U.S. His presentation emphasized the critical roles of key science funding strategies, from standard grants programs, to directed research efforts, cooperative agreements and federal labs. And in the end concluded that many breakthrough advances result not from a systems engineering approach to deciding what to do, but from ideas that are “outside the box.” He also highlighted that science, at its core, is fundamentally a creative endeavor that requires long-term support for people in their careers and for the organizations that host them. AGU has posted a video of the briefings here.

2) NOAA Water Information “Listening Session” in Sacramento May 2016

NOAA invited water management stakeholders from across the West to hear about the National Water Center they are creating in Alabama and to listen to stakeholders interests and needs for weather and water information to support water supply, flood mitigation and endangered species restoration in the West. CW3E was represented by Dr. Ralph, who brought Scripps science into the discussion, and supported major points presented by water managers concerning the vital role of atmospheric rivers in western water decisions. NOAA held one other regional “listening session” – in Alabama, and is holding one more “National” session in July. They will be considering input from these meeting as they develop their agency’s strategies in the coming years to support water information needs for the nation.

3) WSWC S2S Workshop San Diego June 2016

The National Academies of Science recently released a report on the subject of science needed to enable subseasonal-to-seasonal predictions to support decisions. The Western States Water Council (a group supporting the Governors of 17 Western States) organized a regional Workshop in San Diego in early June to discuss both the user requirements for better forecasts and the science opportunities to achieve them. CW3E was represented well, including participation by Sasha Gerhunov, Tamara Shulgina and Marty Ralph, including a presentation by Marty on observing system needs to support the goals.

Atmospheric Rivers Workshop: June 15-17, 2015

Atmospheric Rivers Workshop: June 15-17, 2015

June 19, 2015

An atmospheric rivers (AR) workshop was held 15-17 June at the Seaside Forum at UC San Diego/Scripps Institution of Oceanography (SIO). This workshop was sponsored by the Center for Western Weather and Water Extremes (CW3E) at SIO. Mike Dettinger, David Lavers and Marty Ralph were co-chairs of this workshop. The photo below shows the workshop participants.

Left to right: Jay Jasperse (Sonoma County Water Agency), Jennifer Haase (Scripps), Lauren Muscatine (UC Davis), Brian Kawzenuk (Scripps/CW3E), Tamara Shulgina (Fulbright Scholar at Scripps/CW3E), Sasha Gershunov (Scripps/CW3E), Joel Norris (Scripps and CW3E), Roger Pierce (NOAA/NWS), Harald Sodemann (Univ. of Bergen), Marty Ralph (Scripps/CW3E; Workshop Co-Chair), Nina Oakley (Univ. of Nevada Reno), Mike Dettinger (USGS & Scripps/CW3E; Workshop Co-Chair), Dale Cox (USGS), David Lavers (Scripps/CW3E; Workshop Co-Chair), Jon Rutz (NWS), Jason Cordeira (Plymouth State Univ.), Andrew Martin (Scripps/CW3E), Allen White (NOAA/ESRL), Bin Guan (UCLA), Heini Wernli (ETH Zurich), Larry Schick (US Army Corps of Engineers), Dan Cayan (Scripps/CW3E and USGS), Julie Kalansky (Scripps/CW3E), Ryan Spackman (Science and Technology Corp. and NOAA/ESRL), Maximiliano Viale (Univ. of Chile). Attendees not in picture: Mike Anderson (California Dept. of Water Resources), Bruce Cornuelle (Scripps & CW3E), Duane Waliser (NASA/JPL)

This workshop brought together experts from around the world to survey the current state of atmospheric-river (AR) science and plan the First International Atmospheric Rivers Conference to be held in summer 2016 at Scripps’ Seaside Forum. The group also planned the development of a Monograph on atmospheric rivers that is intended to become the standard reference on the roughly 20 years of AR research. The meeting addressed an outstanding debate in the science community about the physical relationship between ARs, the warm conveyor belt (WCB) in extratropical cyclones and tropical moisture exports (TME) to the extratropics.
The workshop concluded with a plan for the conference in 2016, a strategy for the book, and development of a schematic summary of the relationships between ARs, WCBs and TMEs, each of which plays a critical and complementary role in transporting water vapor through the atmosphere, in terms of horizontal transport and sloped ascent in extratropical cyclones.
The term “atmospheric river” was first coined in 1994 to describe atmospheric water vapor transport across the mid-latitudes. Subsequent research has shown them to be responsible for the majority of extreme hydrologic events in the western United States, Europe, and South America, as well as being critical to water resources in these regions.

For real-time observations and forecasts of atmospheric rivers, please visit the “AR Portal”

Resilience in a Changing Climate: Sonoma County Adaptation Forum

Resilience in a Changing Climate: Sonoma County Adaptation Forum

April 15, 2015

CW3E director Marty Ralph and scientist Julie Kalansky presented at the Sonoma County Adaptation Forum on April 8th. The forum was modeled after state forums, but was the first regional adaptation forum in California. The forum focused on information and approaches to help mitigate the impacts of climate change in Sonoma County and surrounding areas. The audience of over 200 people included city and county leaders, utility managers, environmental groups and the public.

Both Marty and Julie presented in the first session of the morning entitled “Extreme Weather Science; Drought and Deluge in Sonoma County.” Jay Jasperse, Chief Engineer and Director of Groundwater Management at Sonoma County Water Agency, moderated the session. The other panelists included Tim Doherty, from NOAA’s Office for Coastal Management, who discussed the impacts of sea level rise on the region, and Dr. Lisa Micheli, Executive Director of Pepperwood Preserve, who presented on the importance of downscaling climate models to understand the regional response to climate change. Marty Ralph discussed the importance of atmospheric rivers (ARs) to the water supply as well as the potential flooding risk associated with ARs. This led into an explanation of the FIRO, forecast informed reservoir operations, project for improving the water supply resilience of Lake Mendocino. At the end of his presentation he introduced the first part of an ongoing NOAA-NIDIS and Sonoma County Water Agency funded project to examine how the frequency and intensity of ARs may change in future. The link below is to an interview with Marty Ralph about atmospheric rivers and the forum that was broadcasted on North Bay Public Radio.


After Marty’s presentation, Julie presented on the second part of the study including the development of a “mega-drought” stress test for the region and working with the community to understand the all the different dimensions of drought. During Julie’s presentation, she was able to involve the audience and received feedback on the vulnerabilities to drought and the difficult decisions that surround drought. The day was a great success in bringing together scientists, decisions makers and the public to discuss how to make the community more resilient to climate change.

CalWater-2/ARM Cloud Aerosol Precipitation Experiment (ACAPEX)

CalWater-2/ARM Cloud Aerosol Precipitation Experiment (ACAPEX): AGU session

January 2, 2015

The influence of Atmospheric Rivers (ARs) on wet extremes since 1950 are shown by the fraction of AR landfall days (green portion of pie chart). Note, for example, 87% of flood days for the Russian River are AR landfall days.

The Fall 2014 AGU meeting in San Francisco hosted a workshop/press conference describing the upcoming 2015 field campaign: CalWater2 / ARM Cloud Aerosol Precipitation Experiment (ACAPEX). Scientists from Scripps Institution of Oceanography at UC San Diego, the Department of Energy’s Pacific Northwest National Laboratory (PNNL), and NOAA discussed the impetus behind the field campaign to begin in early 2015. The panel described how ground-based, multiple-aircraft, and ship-based measurements will help provide a better understanding of how California gets its rain and snow, how human activities are influencing precipitation, and how the new science provides potential to inform water management decisions relating to drought and flood. One of the related presentations was given by CW3E PI Mike Dettinger. Dr. Dettinger, AGU 2014 Fellow, described historical and future impacts of land-falling ARs. The image above, from his presentation, depicts the influence of AR land-falling days on extreme wet events in California (Russian River floods, flood plain inundations and levee breaks).

Click here for the UCSD/SIO press release about the workshop / press conference.

Click here for the related UCSD/SIO news story about “Refilling California’s Reservoirs—The Roles of Aerosols and Atmospheric Rivers”.

Click here to follow the CalWater-2 / ACAPEX field project forecasts.

First International Atmospheric Rivers Conference

First International Atmospheric Rivers Conference

Note: the full conference has been postponed to 2016

Atmospheric rivers (ARs) play a key role in the water cycle as the primary mechanism conveying water vapor through mid-latitude regions. The precipitation that ARs deliver in many parts of the world, especially through orographic precipitation proceses, is important for water resources; but it also regularly is a hazard, with floods resulting. The aims of the First International Atmospheric Rivers Conference are

  • to discuss and identify differing regional perspectives and conditions from around the world,
  • to evaluate the current state and applications of the science of the mid-latitude atmospheric water cycle, with particular emphasis on atmospheric rivers and associated or parallel processes (e.g., tropical moisture exports),
  • to assess current forecasting capabilities and developing applications, and
  • to plan for future scientific and practical challenges.

The conference aims to bring together experts from academia and applications to form a real community of interests. Questions on the table include: What meteorological conditions constitute ARs and what do not? How can ARs (and related processes) best be identified and categorized? What are the most promising new research directions for putting AR science into its proper meteorological/climatological context and improving its applicability?

Additional contributions are now invited from the scientific community

If you have an interest in ARs (or related topics) and an interest in participating please contact the chairs Marty Ralph or Mike Dettinger.

Please click here for more details.