Graduate Student Tashiana Osborne Represents UCSD at the California State Capitol

Graduate Student Tashiana Osborne Represents UCSD at the California State Capitol

May 3, 2017

CW3E graduate student, Tashiana Osborne, and Communication graduate student, Jahmese Fort, were selected to represent the University of California San Diego (UCSD) at the California State Capitol for the eighth annual UC Graduate Research Advocacy Day on April 19, 2017.

During their day at the state capitol, Osborne and Fort met face-to-face with several state senators, assembly members, and their staff. UC President Janet Napolitano addressed student representatives gathered from all 10 UC campuses during the event. Students engaged with legislators representing both major parties about ways their research projects contribute to making a difference for the lives of Californians and beyond.

Osborne highlighted implications of her research with CW3E, which focuses on investigating and enhancing forecasts of the atmospheric freezing level, the elevation where the air temperature is zero degrees Celsius. Frozen precipitation typically melts to become rain about 200-300 meters below this elevation. Freezing level, therefore, is key in determining the type and amount of precipitation, and ultimately, the amount of runoff generated during and after precipitation events. Freezing level is especially critical in California’s mountainous regions, where precipitation has a unique interaction with the complex and varied topography.

Her work supports the University’s goal to demonstrate the value and impact of UC research and graduate education for California. This research emphasizes the lead role California can have in western weather prediction and monitoring, water resources management, flood safety, and drought preparedness.

Fort and Osborne were also named as the inaugural recipients of the Jane and Jiao Fan, PhD ’94 Prize for Best Advocate for Graduate Studies through the Graduate Division. This prize honors graduate student representatives who are successful in marketing and communicating their own research efforts.

UC President, Janet Napolitano, and graduate student, Tashiana Osborne, at the California State Capitol. Photo credit: Denise Serrano; UCSD Director of Public Affairs.

May 31 – June 2 Big Data and The Earth Sciences: Grand Challenges Workshop

May 31 – June 2 Big Data and The Earth Sciences: Grand Challenges Workshop

April 17, 2017

Abstract deadline extended to April 21st

The Center for Western Weather and Water Extremes (CW3E) of UC San Diego’s Scripps Institution of Oceanography and the Pacific Research Platform (PRP) is excited to announce the organization of a workshop focused on earth sciences and information technology at the University of California San Diego. The workshop is a three-day Grand Challenges workshop May 31 to June 2 in La Jolla, Calif., on the topic of “Big Data and the Earth Sciences”.

CW3E is focused on advancing science and technology to support the unique information needs related to western U.S. extreme weather and water events, such as California’s recent flooding and multi-year drought and associated potential for subseasonal-to-seasonal forecasting. PRP is a consortium of universities in the western U.S. that is building a “science-driven, high-capacity data-centric freeway system on a large regional scale.” Funded by the National Science Foundation, PRP is based in the California Institute for Telecommunications and Information Technology (Calit2), a partnership of UC San Diego and UC Irvine. The workshop will take place in UC San Diego’s Atkinson Hall, headquarters of the Qualcomm Institute (the UCSD division of Calit2).

The goal of the The Big Data and Earth Sciences: Grand Challenges Workshop is to bring thought leaders in Big Data and Earth Sciences together for a three day, intensive workshop to discuss what is needed to advance our understanding and predictability of the Earth systems and to highlight key technological advances and methods that are readily available or in the final stages of development.

Sessions will include:

  • Big data collaborations;
  • Big data research platforms, networks, technologies and visualization;
  • Big data and predictability challenges in earth science data;
  • Pattern detection, segmentation and object recognition for earth sciences;
  • Structuring unstructured data in the earth sciences; as well as
  • Data mining and discovery, machine learning and predictive modeling.

For more information please visit:

Announcement: http://qi.ucsd.edu/news-article.php?id=2829

Official workshop website: http://prp.ucsd.edu/events/big-data-and-the-earth-science-grand-challenges-workshop

Please send abstracts to scottsellars@ucsd.edu

Abstracts are restricted to one page. Please include the abstract title, authors’ names and affiliations. A word document or .pdf is preferred.

CW3E Launches Radiosonde with Potter Valley Elementary School Students

CW3E Launches Radiosonde with Potter Valley Elementary School Students

April 16, 2017

CW3E’s Reuben Demirdjian and Anna Wilson recently conducted a demonstration radiosonde launch at the Potter Valley Fire Department for the Potter Valley Elementary School in the Russian River Watershed. The 5th and 6th grade classes, taught by Lori Clark and Merri Emerson respectively, were very enthusiastic participants in the demonstration launch. During the event the students showed their interest while asking a seemingly endless supply of questions about how the information is collected and why it it is useful. The students wrote a message on the to be launched radiosonde’s plastic exterior (Go Bearcats!), and released the balloon. Topics covered included the research done with the collected data, how the information gained from our experiments might help their strong agricultural community, why the balloon expands as it rises, what the sensors attached to the balloon measure, and how far the balloon might go (atmospheric layers were discussed!). Reuben and Anna, along with CW3E’s Douglas Alden, were also able to interact with the same classes at the start of the 2017 field season in January, when they deployed ground instrumentation including a vertically pointing radar, optical disdrometers, rain gauges, and more instrumentation at the Potter Valley Fire Department. The instrumentation at the Potter Valley Fire Department site has collected a valuable dataset over this historic winter season and CW3E is grateful for the support and collaboration and looks forward to a strong relationship going forward.

CW3E graduate student Reuben Demirdjian gets ready to hand off the radiosonde and balloon to two capable Potter Valley Elementary School students to sample a vertical profile of the atmosphere; Potter Valley Elementary School students watch the balloon ascend.

CW3E Publication Notice: High-Impact Hydrologic Events and Atmospheric Rivers in California: An Investigation using the NCEI Storm Events Database

CW3E Publication Notice

High-Impact Hydrologic Events and Atmospheric Rivers in California: An Investigation using the NCEI Storm Events Database

April 12, 2017

Two 2016 graduates of the M.S. Applied Meteorology program at Plymouth State University, Klint Skelly (May 2016) and Allison Young (December 2016) advised by CW3E Affiliate Dr. Jason Cordeira, worked collectively on understanding the fraction of floods, flash floods, and debris flows (termed high-impact hydrologic events, or HIHEs) that are associated with landfalling ARs in California.

The HIHE–AR relationship was studied over a 10-water year period from Oct 2004 through Sep 2014 with HIHE reports obtained from the National Centers for Environmental Information (NCEI) Storm Events Database and AR dates obtained from a catalog of landfalling ARs from Rutz et al. (2013). Some detailed results are provided below. More information is contained in a manuscript that was recently published in the AGU Geophysical Research Letters: Young, A. M., K. T Skelly, and J. M. Cordeira, 2017: High-Impact Hydrologic Events and Atmospheric Rivers in California: An Investigation using the NCEI Storm Events Database. Geophys. Res. Lett., 44, doi:10.1002/2017GL073077. click here for personal use pdf file

Key Results: A total of 1,415 HIHE reports in California during the 10-year period of study reduced to 580 HIHE days across the different National Weather Service County Warning Areas (CWAs). A large majority (82.9%) of HIHE days occur over southern California; however, a larger fraction of HIHEs are associated with landfalling ARs across northern California (80.8%) as compared to southern California (41.8%). The 580 HIHE days across the different CWAs, when combined, reduced to 364 unique HIHE days for the state of California. A larger number of HIHE days statewide occur during summer (57.1%) as compared to winter (42.9%). Conversely, a larger fraction of HIHE days associated with ARs occur in winter (78.2%) as compared to summer (25.0%), which corresponds to similar values obtained by Neiman et al., (2008) and Ralph and Dettinger (2012).

Figure caption: Total number of HIHE days per (a) CWA and (b–d) month for (b) all of California, (c) northern California, and (d) southern California. The blue bars and denominator represent the total number of HIHE days, whereas the white hatched bars and numerator represent the total number of HIHE days associated with ARs.

The 580 HIHE days across different CWAs, when combined by region, reduced to 88 unique HIHE days for northern California and 301 unique HIHE days for southern California. A larger number of HIHE days across northern California occur during winter (62.5%) as compared to summer (37.5%), whereas a larger number of HIHE days across southern California occur during summer (60.8%) as compared to winter (39.2%). The fraction of these HIHE days that are associated with ARs is higher over northern California (63.6%) as compared to southern California (39.2%).

This study illustrated that HIHE days contained within the NCEI Storm Events Database for CWAs across California can be attributed to landfalling ARs and their associated precipitation extremes. This attribution is largely valid for HIHE days across northern California in the cold season and not necessarily valid for HIHE days across southern California during the warm season. Approximately 57% of all HIHE days in California occurred during the warm-season, mostly in conjunction with flash floods, and 75% of these HIHE days were not associated with ARs. The composite analysis of flash flood days across California illustrated the climatological warm-season flow pattern for precipitation across southern California and closely resembled the type-IV monsoon synoptic pattern as defined by Maddox et al. (1980). This result motivates additional future work that could focus on the role of the North American monsoon and other non-AR processes that produce HIHEs across California.

Support for this project was provided by the State of California-Department of Water Resources and the U.S. Army Corps of Engineers, both as part of broader projects led by CW3E. Dr. Cordeira and his graduate students at Plymouth State University actively collaborate with CW3E on topics related to atmospheric rivers, such as analyzing, understanding, and forecasting their impacts along the U.S. West Coast.

How Many Atmospheric Rivers Have Hit the U.S. West Coast During the Remarkably Wet Water Year 2017?

How Many Atmospheric Rivers Have Hit the U.S. West Coast During the Remarkably Wet Water Year 2017?

April 6, 2017

It has been well established that much of the west coast receives roughly 30-50% of its annual precipitation from landfalling atmospheric rivers. One of the goals of CW3E is to provide timely information on atmospheric rivers and their impacts on water in the West. The analysis presented here is based upon examination of AR conditions on each day from 1 October 2016 through 31 March 2017. Research-based criteria for AR identification have been used, especially the strength of integrated vapor transport (IVT). ARs are also ranked according to a simple scale introduced in 2016 (see inset in the graphic for the scaling).

As would be expected, one reason this winter has been so wet in the west is the large number of landfalling ARs. In addition, a large fraction of these events has been strong, or even extreme, in magnitude, and have caused serious flooding, and incidents like the Oroville Dam spillway issue.

Contacts: F. Martin Ralph, Chad Hecht, Brian Kawzenuk

There have been 45 total atmospheric rivers that have made landfall over the U.S. West coast from 1 October to 31 March 2017. Of the 45 total ARs, 10 have been Weak, 20 have been Moderate, 12 have been Strong, and 3 have been Extreme (Based on IVT magnitude). 1/3 of the landfalling ARs have been “strong” or “extreme”.

The large number of ARs that have made landfall over the U.S. West Coast have produced large amounts of precipitation. The Northern Sierra 8-station index is currently at 83.4 inches, which is just 5.1 inches below the wettest year on record with seven months remaining in the water year. The graphic below, from the California Department of Water Resources, highlights this information.

Odds of Reaching 100% Water Year Precipitation – Apr Update

Odds of Reaching 100% of Normal Precipitation for Water Year 2017 (April Update)

April 6, 2017

Contribution from Dr. M.D. Dettinger, USGS

The odds shown here are the odds of precipitation in the rest of the water year (after March 2017) totaling a large enough amount to bring the water-year total to equal or exceed the percentage of normal listed. “All Yrs” odds based on monthly divisional precipitation totals from water year 1896-2015. Numbers in parenthesis are the corresponding odds if precipitation through March had been precisely normal (1981-2010 baseline).

Click here for a pdf file of this information.

 

 

 

How these probabilities were estimated:

At the end of a given month, if we know how much precipitation has fallen to date (in the water year), the amount of precipitation that will be required to close out the water year (on Sept 30) with a water-year total equal to the long-term normal is just that normal amount minus the amount received to date. Thus the odds of reaching normal by the end of the water year are just the odds of precipitation during the remaining of the year equaling or exceeding that remaining amount.

To arrive at the probabilities shown, the precipitation totals for the remaining months of the water year were tabulated in the long-term historical record and the number of years in which that precipitation total equaled or exceeded the amount still needed to reach normal were counted. The fraction of years that at least reached that threshold is the probability estimate. This simple calculation was performed for a full range of possible starting months (from November thru September) and for a wide range of initial (year-to-date) precipitation conditions. The calculation was also made for the probabilities of reaching 75% of normal by end of water year, 125%, and 150%, to ensure that the resulting tables of probabilities cover almost the full range of situations that will come up in the future.

[One key simplifying assumption goes into estimating the probabilities this way: The assumption that the amount of precipitation that will fall in the remainder of a water year does not depend on the amount that has already fallen in that water year to date. This assumption was tested for each month of the year by correlating historical year-to-date amounts with the remainder-of-the-year amounts, and the resulting correlations were never statistically significantly different from zero, except possibly when the beginning month is March, for which there is a small positive correlation between Oct-Mar and Apr-Sept precipitation historically.]

Contact: Michael Dettinger (USGS)

Odds of Reaching 100% Water Year Precipitation – Mar Update

Odds of Reaching 100% of Normal Precipitation for Water Year 2017 (March Update)

March 8, 2017

Contribution from Dr. M.D. Dettinger, USGS

The odds shown here are the odds of precipitation in the rest of the water year (after February 2017) totaling a large enough amount to bring the water-year total to equal or exceed the percentage of normal listed. “All Yrs” odds based on monthly divisional precipitation totals from water year 1896-2015. Numbers in parenthesis are the corresponding odds if precipitation through February had been precisely normal (1981-2010 baseline).

Click here for a pdf file of this information.

 

 

 

How these probabilities were estimated:

At the end of a given month, if we know how much precipitation has fallen to date (in the water year), the amount of precipitation that will be required to close out the water year (on Sept 30) with a water-year total equal to the long-term normal is just that normal amount minus the amount received to date. Thus the odds of reaching normal by the end of the water year are just the odds of precipitation during the remaining of the year equaling or exceeding that remaining amount.

To arrive at the probabilities shown, the precipitation totals for the remaining months of the water year were tabulated in the long-term historical record and the number of years in which that precipitation total equaled or exceeded the amount still needed to reach normal were counted. The fraction of years that at least reached that threshold is the probability estimate. This simple calculation was performed for a full range of possible starting months (from November thru September) and for a wide range of initial (year-to-date) precipitation conditions. The calculation was also made for the probabilities of reaching 75% of normal by end of water year, 125%, and 150%, to ensure that the resulting tables of probabilities cover almost the full range of situations that will come up in the future.

[One key simplifying assumption goes into estimating the probabilities this way: The assumption that the amount of precipitation that will fall in the remainder of a water year does not depend on the amount that has already fallen in that water year to date. This assumption was tested for each month of the year by correlating historical year-to-date amounts with the remainder-of-the-year amounts, and the resulting correlations were never statistically significantly different from zero, except possibly when the beginning month is March, for which there is a small positive correlation between Oct-Mar and Apr-Sept precipitation historically.]

Contact: Michael Dettinger (USGS)

Director of CW3E to Present at Birch Aquarium

Director of CW3E to Present at Birch Aquarium

March 7, 2017

Director of the Center for Western Weather and Water Extremes, Dr. F. Martin Ralph, will present on atmospheric rivers, their impacts, and their role on California’s water cycle and budget as part of Birch Aquarium’s Perspectives Lectures. The lecture series features presentations on research conducted by scientists from Scripps Institution of Oceanography. Dr. Ralph’s presentation on atmospheric rivers will be held from 7–8 P.M. (doors open at 6:30) on Monday, March 13th. Tickets are $8 for the general public, $5 for students and teachers, and free for Birch Aquarium Members.

Click here for more information.

Current Winter Setting a New California-Wide Record Precipitation Accumulation

Current Winter Setting a New California-Wide Record Precipitation Accumulation

March 7, 2017

Fueled by a string of strong atmospheric rivers (ARs), California’s current winter-to-date accumulated precipitation has hit a new record high level, eclipsing the previous record set during the strong El Niño winter of 1982-83.

The winter began with an unusual early season AR, which contributed 6% of normal annual California-wide precipitation over the period Oct 14-17. Strong AR activity continued in Jan and Feb 2017, with exceptionally strong precipitation Jan 8-10, which produced 14% of normal statewide annual precipitation in just three days and reached R-cat 4 intensity. (R-cat levels measure intense precipitation events; a fuller description of R-cat levels and this event can be found here). The AR during Feb 7-9 produced 9.5% of total annual California precipitation. Together, the latter two AR events produced nearly a quarter of an entire normal year’s precipitation in just 6 days, with each event including extreme intensity AR landfalls in the state.

The figure below shows the water year (Oct 1st – the following Sep 30th) that holds the record for maximum precipitation in California accumulated since the beginning of October for each day of winter. The current water year, 2017, broke the old record in early February and has continued to be the record-holder up to the current date (first week of March). Currently, 1982-82 holds the record for the maximum state-wide accumulated precipitation at the end of May in observations that go back to 1948. The accumulation so far this year is above the pace of 1982-83, but 1982-83 received a significant amount of precipitation in March and early May.

This figure shows California statewide accumulated precipitation estimated from 96 stations distributed across the state, but similar results are seen in the “Eight Station Index”, which uses eight stations in the Sierra Nevada selected for their importance to the state’s water supply. The eight station index is likewise currently at new record levels of accumulated winter precipitation, superseding the previous record-holding winter of 1982-83.

The southern portion of the state, including the greater Los Angeles region and San Diego county, are unusually wet so far this winter but not at record breaking levels. For instance, the Los Angeles region received substantially more precipitation in 2005, which led to widespread flooding, infrastructure damage, and several deaths.

The record-breaking precipitation has led to high values of snow cover, as shown by the yellow line (winter of 2016-2017) below. In the central and southern Sierra Nevada, current values are almost twice what is seen at the typical peak of snow accumulation on April 1st, and significantly above the high values seen during the El Niño winter of 1997-98 (dashed blue line). Snow is an important component of California’s water supply, since it holds the precipitation from intense winter storms, releasing the water more slowly via snow melt.

Contact: David Pierce and Marty Ralph

CW3E AR Update: 13 February 2017 Outlook

CW3E AR Update: 13 February 2017 Outlook

February 13, 2017

Click here for a pdf of this information.

Two ARs Forecast to Impact the West Coast

  • Potentially moderate AR conditions to impact the Pacific Northwest and Northern CA on 15–16 Feb.
  • Up to 5 inches of precipitation could fall over the next 72-hrs over the Coastal Ranges
  • Although forecasts are more uncertain, a second AR is likely to impact most of CA from late 16 Feb through early 18 Feb
  • 7-day precipitation forecasts are as high as 7.6 inches over Northern CA and 6.5 inches over Southern CA

Click IVT or IWV image to see loop of 0-132 hour GFS forecast

Valid 1200 UTC 13 Feb – 0000 UTC 19 Feb 2017


 

 

 

 

 

 

 

 

Summary provided by C. Hecht and F.M. Ralph; 3 PM PT Mon 13 Feb. 2017