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CW3E Publication Notice: The role of hydrological initial conditions on Atmospheric River floods in the Russian River basin

CW3E Publication Notice

The role of hydrological initial conditions on Atmospheric River floods in the Russian River basin

June 27, 2019

CW3E collaborator Dr. Dennis Lettenmaier and his group at UCLA, along with CW3E director F. Martin Ralph, recently published a paper in the Journal of Hydrometeorology titled “The role of hydrological initial conditions on Atmospheric River floods in the Russian River basin”. This article is now available at https://journals.ametsoc.org/doi/abs/10.1175/JHM-D-19-0030.1

Recent studies suggest that observed changes in extreme precipitation associated with a general warming of the Western U.S. have not necessarily led to corresponding changes in floods, and changes in antecedent hydrological conditions could be a primary missing link. They examined the effect of observed warming on antecedent soil moisture (ASM) for the period 1950-2017. They first constructed an hourly precipitation product at 1/32o spatial resolution for the Russian River basin (see Figure 1b for precipitation gauge locations). They used the Distributed Hydrology-Soil-Vegetation Model (DHSVM) to estimate storm total runoff volumes and soil moisture.

Figure 1: a) Study domain, with locations of USGS stream gauges and Hydrometeorolgy Testbed (HMT) soil moisture observation sites shown, and b) precipitation gauge locations. The 15-km buffer for the precipitation gauges selection is shown in gray dashed line in b).

They found that up to 95% of Peaks Over Threshold (POT) extreme discharge events were associated with ARs. The storm runoff-precipitation ratio generally increased with wetter pre-storm conditions, and the relationship was stronger as drainage area increased. They found no trends in extreme precipitation but weak downward trends in extreme discharge. The latter were mostly consistent with weak downward trends in the first 2-day storm precipitation (see Figure 2 for example). They found no trends in ASM, however, ASM was significantly correlated with peak flow. The ASM was affected more by antecedent precipitation than evapotranspiration and hence temperature increases had weak effects on ASM.

Figure 2: Trends in a) observed peak daily streamflow and b) antecedent soil moisture (ASM) from model hourly simulation, and c) first 2-day accumulated storm precipitation of POTN2 extreme discharge events (threshold set to two events per year on average). The p values are shown in plots, categorized by p<=0.01, 0.010.1, with positive trends are marked in blue and negative in red. The p values not greater than 0.1 are marked in bold font.

Ralph et al. (2019) examined the relationship between the AR scale and major flooding at the USGS Gauge 11467000 (Russian River near Guerneville) (see Table 5 in their paper). They found that 6 out of 10 AR events in the highest category (in terms of IVT intensity and AR duration) were associated with major flooding during 1980-2017. They hypothesized that the three that did not lead to major flooding (one occurred when streamflow data were not available) were related to dry soils. This study here showed that the ASM values were less than 20% (volumetric water content expressed as %) for these three events, which corroborates the hypothesis of Ralph et al. Furthermore, 5 out of the 6 AR events that led to flooding had ASM values greater than 32%. The remaining one was the smallest flood event among the six, with an ASM of 22%.

The research supported herein was funded by the CW3E at the Scripps Institution of Oceanography via a grant from the California Department of Water Resources, with Dr. Ralph serving as Principal Investigator.

Cao, Q., A. Mehran, F.M. Ralph, and D.P. Lettenmaier, 2019: The role of hydrological initial conditions on Atmospheric River floods in the Russian River basin, J. Hydrometeor., DOI:10.1175/JHM-D-19-0030.1..

CW3E Participates in U.S. State Department-sponsored Foreign Ambassador Visit

June 26, 2019

Members of Scripps Institution of Oceanography and CW3E had the pleasure of welcoming over 35 foreign ambassadors representing countries across four continents to the Ellen Browning Scripps Memorial Pier on June 17, 2019 as part of a U.S. State Department-sponsored visit. The goal of the visit, part of the 25th Experience America trip to San Diego, was to spotlight San Diego as an innovative city making advances in science, technology, defense, and more. A visit to UC San Diego showcased the university as a hub of innovation, with the research and academic community sharing how the university works to understand, monitor, and communicate the world’s most pressing environmental problems.

Ambassadors heard from faculty, staff, and student researchers about cutting-edge earth and planetary science on local and global horizons as they toured the Scripps Pier. CW3E’s work was featured front-and-center as Douglas Alden and Brain Kawzenuk demonstrated a major component of Atmospheric River field research by leading a weather balloon launch. Assisted by Her Excellency Mathilde Mukantabana, Ambassador of the Republic of Rwanda and His Excellency Arjun Kumar Karki, Ambassador of the Federal Democratic Republic of Nepal, the diplomats were able to gain hands-on experience and develop a deeper understanding of how researchers at CW3E, and across the globe, study the atmosphere.

Feedback from ambassadors suggested the balloon launch was a highlight of the tour. The event was a fantastic outreach opportunity to share Scripps’ and CW3E’s scientific expertise and data collection methods with a broader community.

Douglas Alden and Brian Kawzenuk facilitate a weather balloon launch for foreign ambassadors at the U.S. State Department-sponsored 25th Experience America trip on the Ellen Browning Scripps Memorial Pier

The group of foreign ambassadors and Scripps personnel on the Ellen Browning Scripps Memorial Pier

The AR Colloquium Summer School Kicks-Off

June 27, 2019

CW3E is hosting the Atmospheric River (AR) Colloquium Summer School at Scripps Institution of Oceanography which began on Monday, June 24^th. The Colloquium is two full weeks of lectures on atmospheric rivers by leading atmospheric science researchers on a range of topics based on the soon to be released AR monograph. In addition to the specially crafted lectures, the agenda has built in time for the students to interact with the researchers and gain hands-on experience.

The overarching goal of the colloquium is to provide the next generation of atmospheric scientists with an in depth look at the cutting edge techniques in understanding, monitoring, and predicting ARs and their associated high-impact weather. In order to achieve this goal, the Colloquium brought together a diversity of early career researchers. The attendees range from a recent high school graduate to recent Ph.D graduates and come from 25 different institutions located in 11 countries.

During the first days of the conference, attendees toured the Scripps campus, got to know each other during an icebreaker, formed teams and began design of their Colloquium projects. They also heard lectures on the history of AR research, AR reconnaissance and other observations, hydrologic impacts, and ARs in the paleoclimate.

The AR Colloquium is being sponsored by the USACE.

Top row (Instructors) L to R: Larry Schick, Alexandre Ramos, David Lavers, Marty Ralph, Mike Dettinger, Anna Wilson, Rene Garreaud, Ashley Payne, Jon Rutz, Bill Neff, Hans Christian Steen-Larsen, Irina Gorodetskaya
Middle row (Students) L to R: Mike Sierks, Will Chapman, Christoph Boehm, Tyler Leicht, Tomas Gomez, Eric Shearer, Jonathan Wille, Terry Pagano, Sol Kim, Gino Passalacqua, Dabeen Kim, Shawn Roj, Diogo Luis, Alexander Lojko, Timbo Stillinger
Bottom row (students) L to R: Cody Poulsen, Anastasiia Chyhareva, Allison Michaelis, Annareli Morales, Emily Slinskey, Deveshi Buch, Ana Caldeirinha, Olusola Ayantobo, Sophie Uluatam, Carolina Viceto, Pedro Sousa, Melanie Lauer, Tamara Shulgina, Christine Albano, Dhana Lakshmi Douluri

CW3E Invited to Present at the California Utility Forecasting Meeting

June 25, 2019

Meredith Fish and Eric Pytlak of Bonneville Power Administration and fellow Penn State alumni. The meeting was hosted in Southern California Edison’s Emergency Operations Center.

CW3E collaborator Dr. Dan Cayan, CW3E graduate student Meredith Fish, and Dr. Laura Engeman were invited by San Diego Gas & Electric (SDG&E) to present at the annual California Utility Forecasting Meeting (CUFM) hosted by Southern California Edison in Irwindale, CA. CUFM is an annual gathering of meteorologists from the utilities, select universities, and government agencies like the National Weather Service and US Forest Service. This meeting brings together West Coast utility companies such as SDG&E, Pacific Gas & Electric, Southern California Edison and Bonneville Power Administration to discuss internal advances in fire weather modeling and forecasting, monitoring networks, and load forecasting. Dr. Cayan and Ms. Fish discussed climate change impacts and atmospheric rivers respectively. Dr. Laura Engeman, from the Center for Climate Change Impacts and Adaptations at the Scripps Institution of Oceanography (SIO), discussed sea level rise. Each SIO representative focused their presentations on specific issues facing utility companies such as more frequent wildfires, impactful and difficult to forecast phenomena such as narrow cold frontal rainbands, and sea level rise impacting distribution centers.

CW3E Publication Notice: A critical examination of a newly proposed interhemispheric teleconnection to Southwestern US winter precipitation

CW3E Publication Notice

A critical examination of a newly proposed interhemispheric teleconnection to Southwestern US winter precipitation

June 23, 2019

Peter Gibson and Duane Waliser (NASA JPL/CalTech), along with CW3E scientist Mike DeFlorio, recently published a reply in Nature Communications to a research article investigating interhemispheric drivers of subseasonal-to-seasonal (S2S) predictability of southwestern U.S. precipitation.

The purpose of the reply was to test the robustness of the claim that New Zealand SST anomalies play an important role in altering atmospheric circulation in the North Pacific that subsequently influences southwestern U.S. winter precipitation variability. Gibson et al. (2019) focused on additional testing of the lagged correlation strength between SST anomalies in key regions proposed in the original article. Gibson et al. (2019) found that non-stationarity, memory, and shared variability with other well-known modes of internal variability make a large contribution to the reported correlation strength between these regions of interest. Using large model simulations with multiple initial conditions, it was shown that similar associations between these regions can often arise by chance alone. The proposed mechanism, whereby SST anomalies near New Zealand enhance remote adiabatic warming and reduce cloud cover, was also called into question from the perspective of other satellite and reanalysis datasets.

Uncovering new physical mechanisms that may lead to increased S2S prediction skill of western U.S. precipitation is a challenging and fundamental task that the partnership between CW3E and JPL continues to undertake. This is an important issue for our stakeholders at the California Department of Water Resources, and more generally for water resource managers across the southwestern and western United States.

Gibson, P. B., D. E. Waliser, and M. J. DeFlorio (2019), A critical examination of a newly proposed interhemispheric teleconnection to Southwestern US winter precipitation. Nature Communications, 10, 2687. https://doi.org/10.1038/s41467-019-10528-y.

Original article:

Mamalakis, A., J. Y. Yu, J. T. Randerson, A. AghaKouchak, & E. Foufoula-Georgiou (2018). A new interhemispheric teleconnection increases predictability of winter precipitation in southwestern US. Nature Communications, 9(1), 2332. https://doi.org/10.1038/s41467-018-04722-7.

CW3E Publication Notice: The Effect of El Niño on Flood Damages in the Western United States

CW3E Publication Notice

The Effect of El Niño on Flood Damages in the Western United States

June 19, 2019

CW3E postdoc Tom Corringham and coauthor Daniel Cayan have published a paper in Weather Climate and Society entitled “The Effect of El Niño on Flood Damages in the Western United States.”

The study quantifies insured flood losses across the western United States from 1978 to 2017, presenting an analysis of National Flood Insurance Program (NFIP) claims and losses over this period. While considerably lower (only 3.3%) than broader measures of direct damages measured by a National Weather Service (NWS) dataset, NFIP insured losses are highly correlated to NWS annual damages and provide flood impacts at a finer degree of spatial and temporal resolution. The NFIP data reveal that 1% of extreme events, covering wide spatial areas, caused over 66% of total insured losses.

Connections between extreme events and El Niño–Southern Oscillation (ENSO) that have been documented in past research are borne out in the insurance data. In coastal Southern California and across the Southwest, El Niño conditions have had a strong effect in producing more frequent and higher magnitudes of insured losses, while La Niña conditions significantly reduced both the frequency and magnitude of losses. In the Pacific Northwest, the opposite pattern appears, although the effect is weaker and less spatially coherent.

Figure 1: ENSO composites and mean extended cool season (ONDJFM) monthly losses per $100,000 of coverage. Enhanced losses are colored red and reduced losses are blue, with color intensity on a log scale. Boxed grid cells are significantly different from the overall ONDJFM mean at p < 0.1, using analysis of means analysis. Boxed cells with crosses are significant at p < 0.05. Significantly enhanced losses are seen in the Pacific Northwest during La Niña months and in Southern California in El Niño months.

The persistent evolution of ENSO offers the possibility for property owners, policy makers, and emergency planners and responders that unusually high or low flood damages could be predicted in advance of the primary winter storm period along the West Coast. Within the 40-year NFIP history, the study finds that the multivariate ENSO index (MEI) would have provided an 8-month look-ahead for heightened damages in Southern California.

Figure 2: Correlations of monthly insured losses vs contemporaneous and leading monthly MEI. Strongly significant (p < 0.01) positive correlations are seen in Southern California up to 8 months ahead of time. The signal is positive but not significant in Northern California. Negative and weakly significant (p < 0.1) correlations are seen in Oregon and Washington up to 3 months ahead.

Corringham, T.W. and D.R. Cayan, 2019: The Effect of El Niño on Flood Damages in the Western United States. Wea. Climate Soc., 11, 489-504, https://doi.org/10.1175/WCAS-D-18-0071.1 .

CW3E Participates in ECMWF’s Workshop on Observational Campaigns for Better Weather Forecasts

June 14, 2019

CW3E’s Luca Delle Monache (Deputy Director), Forest Cannon (Data Analyst), and Anna Wilson (Field Research Manager), along with SIO collaborator Jennifer Haase, recently attended the European Centre for Medium-Range Weather Forecasts’ Workshop on Observational Campaigns for Better Weather Forecasts, held in Reading, UK, on June 10-13, 2019. The workshop goal was to strengthen the links between observational campaigns and Numerical Weather Prediction (NWP) to (1) help observational campaigns optimize their use of forecasts and knowledge of forecast errors and (2) help NWP system development make better use of observational campaign data.

The CW3E scientists, along with AR Recon Co-PI Vijay Tallapragada (NCEP), and AR Recon partners Jim Doyle (NRL), Jeremy DeHart and Ryan Rickert (Air Force 53rd Weather Reconnaissance Squadron), and David Lavers (ECMWF), all spent time in their presentations describing efforts and results related to the ongoing AR Reconnaissance (AR Recon) work. The other CW3E attendees each presented posters on AR Recon and Forecast Informed Reservoir Operations observational campaigns. The Air Force provided an operations briefing in the Weather Room. Dr. Tallapragada, Co-PI of AR Recon, also delivered a presentation focusing on AR recon prepared by CW3E Director Marty Ralph. Other field campaigns covered at the workshop included NAWDEX, polar campaigns, cloud observing campaigns, among many other topics. Presentations focused on the use of ECMWF forecasts in planning field efforts, and the utility of field data to improve model parameterizations and weather forecasts. There were many fruitful discussions regarding ongoing efforts structured into the workshop. CW3E is grateful for the opportunity to participate in such a dynamic community of experts. All presentations were recorded and are available online on the workshop website. AR Recon represents a partnership led by CW3E including NCEP, NRL, ECMWF and NCAR and depends upon support from the Air Force’s 53rd Weather Reconnaissance Squadron and NOAA’s Office of Marine and Aircraft Operations. The CA Department of Water Resources and the US Army Corps of Engineers provide the core support for dropsondes and planning.

Attendees of the workshop at ECMWF.

AMS Broadcast Conference Attendees Visit CW3E

June 13, 2019

Research and Development Engineer Douglas Alden describes the instrumentation deployed on the pier and throughout California, as well as the radiosondes and dropsondes deployed by CW3E. Photo credit: Lauren Wood (Scripps)

CW3E and members from the Scripps Institution of Oceanography Communications Office had the pleasure of welcoming a group of 45 broadcast meteorologists to Scripps on June 11, 2019. The 47th American Meteorological Society’s Conference on Broadcast Meteorology was hosted in San Diego this week, and a group of conference attendees made a visit to Scripps. The group was made up of professionals associated with the broadcast meteorology community who traveled from all over the country to attend the conference.

After a welcome message from Scripps Director of Strategic Communications Lauren Wood, CW3E’s Brian Kawzenuk gave a presentation describing the CW3E program and research that is currently being done, as well as highlighting several of the unique forecast and observational products hosted on the CW3E website. After the presentation, the group was led on a tour of the Ellen Browning Scripps Memorial Pier by Douglas Alden, a research and development engineer at Scripps. During the tour the group was introduced to ongoing research at Scripps and instrumentation deployed on the pier. They also participated in a weather balloon launch.

The interaction between CW3E and broadcast meteorologists can be key in transferring the research and products developed at CW3E to the general public. The hazards and impacts that much of CW3E’s research focuses on should be communicated to the public, and a working relationship with the broadcast meteorology community is a critical step in this process.

Attendees learn about ongoing research at CW3E. Photo credit: Lauren Wood (Scripps)

Members of the broadcast meteorology community tour the Ellen Browning Scripps Memorial Pier. Photo credit: AMS Broadcast Conference

CW3E Graduate Student Attends the American Meteorological Society Summer Policy Colloquium

June 11, 2019

CW3E graduate student, Meredith Fish, was selected to attend the June 2019 American Meteorological Society (AMS) Summer Policy Colloquium, and was awarded full support by the National Science Foundation (NSF) through a nationwide competition.

During the 10-day AMS Summer Policy Colloquium hosted at the American Association for the Advancement of Science (AAAS) in Washington, D.C., Meredith learned from numerous perspectives on how science can inform policy and how policy governs science. The colloquium attendees visited the U.S. House of Representatives and the Senate, hearing from Senators and House Representatives, scientists who transitioned into policy, State Department negotiators, congressional science policy analysts and staffers, AAAS fellows, non-profits, registered lobbyists, leaders in private and public partnerships, and others. One highlight of the colloquium was the opportunity to have dinner with, hear from and engage with Dr. Kelvin K. Droegemeier, Director of the White House Office of Science and Technology Policy, fellow meteorologist, and previous attendee of the AMS Summer Policy Colloquium.

The attendees engaged in a group exercise on weather, water and climate legislation to conduct a mock Senate committee markup and vote on legislation relevant to the Earth Science community. Divided into small groups, we each ‘represented’ Senators and his/her staff to understand the bills proposed, understand the political views of and landscape for the office we represented, develop our own alternative or complementary policy approaches and devise and implement a markup strategy. This exercise and others highlighted some of the intricacies, nuances, and varying priorities involved in politics.

AMS Summer Policy Attendees in front of the U.S. Capitol Building. (Photo by AMS)

AMS Summer Policy Colloquium attendees on the last day pictured with the program lead, Dr. Bill Hooke (back row left).

AMS Summer Policy Colloquium attendees sitting in the House of Representatives hearing room for the Committee of Science, Space and Technology. After the picture, the attendees were granted permission to sit in the elevated seats, as seen on the sides of the photo, reserved for serving House of Representative members.

Climate Projections and Community Resilience: CW3E Explores the Yampa River Basin

June 6, 2019

The Yampa River is one of the wildest remaining major tributaries of the Colorado River and supports a rich ecosystem, local agriculture and ranching, and a robust recreation industry. It also provides crucial water supplies to local stakeholders and locations as far removed as Arizona and Southern California. A multitude of environmental and societal factors are expected to be affected by climate change in the Yampa River Basin, and are pertinent to other watersheds around the American West.

This June, CW3E travelled to Steamboat Springs, Colorado, for the second Yampa Basin Rendezvous. This event was a community-oriented event organized by CW3E and partners from Colorado Mountain College, Yampa Valley Sustainability Council, Friends of the Yampa, and Wyndham Resorts. During the event, which built directly off the inaugural Rendezvous held in 2018, participants examined the Yampa River Basin through the lens of climate change and community resilience. The workshop included talks by regional experts, discussion panels, afternoon field learning, and a community event. We explored the science behind climate projections with a focus on the Yampa, learned how climate change is expected to impact various stakeholders, and what adaptation and mitigation plans are in place, as well as where challenges remain. This dialogue with the local community allowed pairing of research interests of graduate students, post-doctoral scholars, researchers, staff and faculty from CW3E with the community’s expertise on challenges and successes of resilience planning and practice in the Yampa. This effort helped to identify how additional climate and weather information and research could support climate resilience planning in the Colorado River Basin and California, and strengthened connections between those who live in the Yampa basin and some of those who depend on its water.

Speakers present during morning panels at the Yampa Basin Rendezvous 2019. Left, David Pierce of Scripps Institution of Oceanography; right, Bill Atkinson of Colorado Parks and Wildlife.

Afternoon field learning at Steamboat Ski and Resort Corporation (SSRC) during the Yampa Basin Rendezvous 2019, led by Lance Miles of SSRC and Rick Henderson of the US Forest Service.

CW3E and friends after an afternoon river run the evening before Yampa Basin Rendezvous 2019, generously led by Kent Vertrees and John Saunders of Colorado Mountain College. Left to right: Zhenhai Zhang, Mike DeFlorio, Ben Hatchett, Allison Michaelis, Anna Wilson, Will Chapman, Mike Sierks, Douglas Alden, and Clinton Alden.