California Drought: 2013/14 4th driest water year on record

California Drought: 4th driest water year depletes reservoirs

October 1, 2014

CW3E partners at the Sonoma County Water Agency (SCWA) are quoted in a recent article in the Santa Rosa Press Democrat marking water year 2013/14 as the 4th driest on record.


The baked lakebed of Lake Mendocino shows a carp head (photo taken 30 September 2014 by Press Democrat photographer Kent Porter)

Dwindling reservoir levels are one of the main concerns due to the drought – Lake Mendocino is only 27% full. The article mentions the research partnership between SCWA and CW3E. Understanding the key role of atmospheric rivers in the area’s water supply is a focus of the research agreement. Please find the full article (including additional photos and a video) at:

NASA NEWS program selects joint JPL+CW3E AR proposal

NASA NEWS program selects joint JPL+CW3E AR proposal

August 28, 2014


NASA recently announced it selections for its 2013 NASA Energy and Water Cycle (NEWS) solicitation. Included in the selections was a proposal led by Duane Waliser of JPL as PI, and Marty Ralph of CW3E and Bin Guan of UCLA as co-PIs. The proposal aims to study “Atmospheric Rivers: Water Extremes that Impact Global Climate, Regional Weather and Water Resources”, with objectives on observation characterization, including emphasis on atmospheric and terrestrial water budgets, and on the development of methodologies and metrics for model evaluation. The proposal is for a three year study, and funding is expected to start early in FY 2015.

Publication Notice: An Airborne Study of an Atmospheric River over the Subtropical Pacific during WISPAR: Dropsonde Budget-Box Diagnostics and Precipitation Impacts in Hawaii

CW3E Publication Notice

An Airborne Study of an Atmospheric River over the Subtropical Pacific during WISPAR: Dropsonde Budget-Box Diagnostics and Precipitation Impacts in Hawaii

Satellite image swath at 1921 UTC 3 Mar 2011 of IWV (cm; color scale at bottom) from the SSMIS. The unadjusted G-IV flight track is superimposed, along with dots marking the positions and times of the dropsonde releases late on 3 Mar (2007–2343 UTC) and early on 4 Mar (0003–0302 UTC) 2011. The operational rawinsonde locations at Lihue (LIH) and Hilo (ITO) on Hawaii are shown. Manually smoothed satellite-derived sea surface temperatures (8C; contours) from the Reynolds et al. (2007) daily 0.25830.258 resolution optimally interpolated infrared product are also shown. (From Neiman et al. 2014.).

The upcoming CalWater-2 experiment, which is organized by CW3E scientists and others from NOAA, NASA, DOE, USGS and elsewhere, will be using research aircraft to observe atmospheric rivers over the Northeastern Pacific Ocean and U.S. West Coast. This presents an opportunity to measure atmospheric river (AR) structure and embedded physical processes that control the water vapor transport budget. This paper develops some of the key diagnostic tools needed and demonstrates them using a flight pattern and dropsondes designed to calculate the vertical profile of water vapor flux divergence (and other key parameters) in an AR. These tools and associated flight strategies will be critical to future airborne field campaigns that will enable CW3E and colleagues to diagnose key AR-relevant physical processes and to then assess in detail their representation in weather and climate models.

In 2011 a short airborne campaign was conducted to demonstrate the ability of an unmanned aircraft (Global Hawk) to fly over ARs and sample them using dropsondes. As part of this successful demonstration of UAS technology – WISPAR – a special flight of the NOAA G-IV aircraft was also conducted. The paper presents a summary of this flight, including use of drospondes from a box pattern over an AR to calculate vertical profiles of divergence, water vapor flux divergence, sensible heat flux divergence and vertical air motions. The same AR studied here also produced over 10 inches of rain on the normally dry side of the Hawaiian Islands due to the anomalous water vapor transport conditions associated with the AR hitting the region.


The Winter Storms and Pacific Atmospheric Rivers (WISPAR) experiment was carried out in January–March 2011 from the National Aeronautics and Space Administration (NASA) Dryden Flight Research Center as a demonstration for utilizing unmanned aerial systems in meteorological research and operations over data-sparse oceans. One of the campaign’s three missions was coordinated with a manned National Oceanic and Atmospheric Administration Gulfstream-IV (G-IV) flight out of Honolulu, Hawaii, on 3–4 March 2011. The G-IV, which flew through a developing atmospheric river (AR) west of Hawaii, represents the cornerstone observing platform for this study and provided the southernmost dropsonde observations of an AR published to date in the subtropical Northern Hemisphere. The AR exhibited characteristics comparable to those observed in previous studies farther north in the subtropics and midlatitudes, save for larger integrated water vapor and weaker winds in the AR core and stronger equatorward vapor fluxes in the shallow post-cold-frontal northeasterly flow. Eight dropsondes released in a ~200-km-wide box formation provided a novel kinematic assessment of tropospheric vorticity, divergence (mass, water vapor, sensible heat), and vertical velocity in the AR region, as well as sea surface fluxes. The budget-box diagnostics were physically consistent with global-gridded reanalysis datasets, while also providing useful additional kinematic and thermodynamic information on the mesoscale. Meteorological impacts of the AR were assessed on Hawaii’s island of Kauai, where the state’s heaviest rainfall was observed for this case. Rainfall on Kauai was modulated significantly by its steep orography, including on the normally dry side of the island where heavy rains fell.

A personal use copy of the article is available here.

Mike Dettinger elected AGU Fellow

CW3E congratulates Mike Dettinger – 2014 AGU Fellow<

July 30, 2014

CW3E congratulates PI Dr. Michael Dettinger’s election to AGU’s 2014 class of Fellows. This honor is a compliment to Mike’s long career and is presented with the citation “For insightful and useful research in understanding how climate and weather affect the variability of hydrologic systems”. Only one in a thousand members is elected AGU Fellow each year so this is a prestigious achievement. CW3E PI and colleague Dr. Dan Cayan notes “Mike was among the first to explain how hydrologic variability is organized across continental to global scales. Mike’s contributions also include new insights about how longer period climate variation may affect shorter period hydrologic phenomena. Mike’s recent emphasis on understanding North Pacific storms, with close ties to Marty Ralph and colleagues, has produced a sharper image of how “atmospheric rivers” produce most of the floods along the West Coast and deliver a large portion of its water supply.”

CW3E welcomes Reuben Demirdjian

CW3E welcomes Reuben Demirdjian

June 24, 2014

CW3E is pleased to welcome Reuben Demirdjian. Reuben joins CW3E to pursue his doctoral degree at Scripps Institution of Oceanography. Reuben completed his undergraduate degree at UC Santa Barbara in physics. “I met Dr. Ralph at the Scripps Open House and was impressed with the group he is building and his enthusiasm for understanding the role atmospheric rivers play in the precipittion regime of California and the western US,” Reuben said. Reuben is getting a head start this summer learning tools, especially the WRF (Weather, Research and Forecasting) model, and use of dropsonde observations from research aircraft.

CalWater 2015 Advanced Planning Workshop

CalWater 2015 Advanced Planning Workshop

June 10, 2014

CW3E is pleased to host a CalWater 2015 Advanced Planning Meeting for Forecasting at Scripps Institution of Oceanography from 24-25 June 2014. The purpose of this meeting was to begin preparing for a major deployment of 3 aircraft, a ship and ground-based observation sites this winter. Specifically the aim was to focus on the development of forecast requirements specific to the field experiment and implementation of forecasts for meteorological and chemical/aerosol dimentions of CalWater-2015. Coordinators of this meeting were Jason Cordeira (Plymouth State University), Andrew Martin (Scripps Institution of Oceanography) and Jonathan Rutz (NOAA/National Weather Service). Other participants included Ryan Spackman and Natalie Gaggani (NOAA STC/PSD) and Roger Pierce (NOAA/NWS).

Sonoma County Water Agency (SCWA) and Scripps Institution of Oceanography establish a Cooperative Agreement for Scientific and Educational Cooperation

Sonoma County Water Agency (SCWA) and Scripps Institution of Oceanography establish a Cooperative Agreement for Scientific and Educational Cooperation

July 2014

SCWA entrance; Santa Rosa, California.

Sonoma County Water Agency (SCWA) provides water for over 600,000 people from the Russian River in northern California. It also supports a vibrant economy famous for its wine and tourism, while at the same time working to restore endangered salmon species. SCWA performs this vital role in the face of a climate characterized by major swings in precipitation, ranging from major flooding to drought. These swings are largely controlled by the presence, absence and strength of atmospheric river storms, a topic for which CW3E provides deep and cutting-edge knowledge.

During meetings between CW3E and SCWA it became apparent that key capabilities at CW3E and needs for new information and tools at SCWA were well aligned. This led to the development of joint projects, including some with NOAA and/or USGS, for which it would be advantageous to formalize the relationship in a way that provides space for CW3E staff to spend productive time interacting with SCWA staff and their stakeholders. It also is seen as an opportunity for SCWA to highlight its forward looking culture of innovation geared toward improving its services and stewardship.

Specifically, the agreement sets forth to initiate cooperation to further the development of basic scientific and applied research with goals of advancing research in ocean science and meteorology, gaining a more fundamental understanding of the ocean and meteorology, and benefiting society at large. It also aims to maintain and promote channels of cooperation and communication that permit the exchange of academic and scientific knowledge, which will assist the Water Agency in carrying out water supply management more efficiently and effectively and the U.S. Army Corps of Engineers with flood control operations.

Three early projects form the initial use of this agreement: 1) study of the role of atmospheric rivers in filling Lake Mendocino and potentially offering predictability to retain water without increasing flood risk, 2) a NOAA-funded climate program office project to study the role of atmospheric rivers in ending droughts on the Russian River, including how this may be affected by a changing climate, as well as development of a drought scenario and drought readiness assessment, and 3) cooperation in developing a feasibility assessment project for the potential use of forecast-informed reservoir operations (FIRO) for Lake Mendocino in cooperation with the US Army Corps of Engineers. The FIRO effort is taking a major step forward through a workshop that is being conducted in August 2014 at Scripps. Representative of the partnership this important cooperative agreement creates, the FIRO Workshop is co-chaired by Jay Jasperse, Chief Engineer for SCWA, and F. Martin Ralph, Director of CW3E at UCSD/Scripps.

Publication Notice: Chemical properties of insoluble precipitation residue particles

CW3E Publication Notice

Chemical properties of insoluble precipitation residue particles

Jessie Creamean posing for a photo while clearing snow from the top of the NOAA trailer at Sugar Pine Dam after the storm on 2/25/11.

This article provides an in-depth analysis of resuspended residues from precipitation samples collected at a remote site in the Sierra Nevada Mountains in California during the 2009-2011 winter seasons. These residues may be used as a benchmark for classification of insoluble precipitation. Knowledge of the precipitation chemistry of insoluble residues coupled with meteorological and cloud microphysical measurements will ultimately improve our understanding of the link between aerosols, clouds, and precipitation.

This paper represents a significant milestone from the CalWater experiment, which is led by members of UCSD/Scripps’ new Centers on aerosols (CAICE) and extreme events (CW3E), as well as NOAA, DOE, NASA, USGS. It also highlights the multi-disciplinary research stimulated by CalWater, and the partnerships between key researchers across organizations. The lead author, Jessie Creamean, received her PhD in atmospheric chemistry from UCSD under Kim Prather using CalWater data, and is now bringing that expertise to a primarily meteorological group in NOAA as she pursues emerging topics in aerosol-precipitation interactions in collaboration with CW3E scientists.

A personal use copy of the article is available here.

CalWater-ACAPEX 2015 Planning Workshop

CalWater-ACAPEX 2015 Planning Workshop

Scripps Institution of Oceanography

La Jolla, California

CalWater 2 Co-Leads: Marty Ralph, Kim Prather, Dan Cayan (Scripps)

Organizing Committee: Chris Fairall (NOAA), Ruby Leung (PNNL), Andrew Martin (Scripps), Ryan Spackman (NOAA/STC)

CalWater2 – ACAPEX Observational Strategy Winter 2014-15

CalWater-2 took major steps from vision to reality on 22-24 April 2014 at Scripps Institution of Oceanography when roughly 40 key individuals (scientists, engineers, aircraft and ship managers, and students) met to plan for major field deployments in 2015. The following facilities are committed (or nearly so) to a field campaign between roughly 10 January and 10 March 2015:

  • DOE – G-1 aircraft
  • DOE AMF-2 ocean-atmosphere facility on the NOAA Research Vessel (ship) Ron Brown
  • NOAA G-IV aircraft
  • NOAA P-3 aircraft
  • ATOFMS mobile, land-based aerosol-sensor suite
  • EFREP hydrometeorological Mesonetwork in California

The DOE facilities are part of the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) experiment addressing (1) aerosol impacts on clouds and precipitation and (2) atmospheric rivers. The NOAA facilities were requested also based on the CalWater vision, with an emphasis on atmospheric-river science questions.

The workshop concluded with a plan for specific start and end dates for each facility, narrowed options for where to operate them, a plan for a field operations center (and a specific possible location), strategies for developing coordinated ship and aircraft operations, and plans for the forecasting capabilities needed to guide missions. In addition, the 12-member CalWater Core Scientific Steering Group met afterword and reviewed plans for 2016-2018 and strategies to advance the longer term Calwater Vision. The Steering Group committed to organizing two special sessions and a side meeting (for last minute coordinations of the 2015 CalWater and ACAPEX activities) at the Fall Meeting of AGU in December 2014, and a journal article describing the program. The proposed AGU sessions are:

  1. CalWater Theme 1: Cloud-Aerosol-Precipitation Interactions in California (Conveners: Daniel Rosenfeld, Kimberly Prather),
  2. Atmospheric Rivers: Observations, Dynamics, Modeling, Impacts and Applications (Conveners: Marty Ralph, Duane Waliser, Jason Cordeira).

The presentations from the Workshop are available here.

Workshop Sponsored by:

  • Scripps, Center for Western Weather and Water Extremes (CW3E)
  • Scripps Center for Aerosol Impacts on Climate and the Environment (CAICE)
  • Science and Technology Corporation (STC)

Workshop Sponsored by:Workshop Participants

Photo of most workshop participants at the CalWater 2015 – ACAPEX workshop at Scripps, April 2014.

CalWater2 Workshop Participants