Staff Notes Daily Calendar Events

A plain-language abstract is an incredibly effective science communication tool because it allows researchers to reach a wider audience by summarizing papers in terms that are accessible to people outside of a specific scientific circle.

In this webinar, learn how to identify your audience, reduce jargon, determine what key points to hit, and more.

American Geophysical Union Webinar

Thu, Aug 30, 2018

12:00 - 1:00 PM MDT (2:00 - 3:00 PM EDT)

Register to attend: https://register.gotowebinar.com/register/2391323833530123266

"Stability Analysis of Inline ZFP Compression for Floating-Point Data in Iterative Methods"

Alyson Fox Lawrence Livermore National Lab

ZFP, a state-of-the-art lossy compression algorithm, can easily be used inline during numerical simulations due to the inherent locality of the algorithm. ZFP decomposes a solution state into 4d blocks, which are subsequently compressed (decompressed) independently. In a numerical simulation, the solution state already contains traditional errors, e.g., floating-point round-off, truncation error, and discretization error. The information that is lost during ZFP compression may represent the traditional errors, however, any additional error caused by ZFP could contaminate the current iterate. It is important to understand if the error from ZFP compression overwhelms the other sources of error. The goal of this work is to analyze the stability of using ZFP in fixed precision inline in time-evolving iterative methods. We introduce the infinite bit vector space and define corresponding operators for each step of ZFP, to establish an error bound for both a static and iterative implementation of ZFP in fixed precision. To conclude, we present results from several numerical experiments to observe the validity of our established error bounds.

Bring your lunch!

Wednesday, September 5, 2018 12:00pm - 1:00pm ML, Room 680 Tower B (Penthouse)

The Sundowner Winds Experiment (SWEX) First Intensive Campaign: understanding downslope windstorms in the Santa Ynez Mountains, Santa Barbara, CA

Sundowner winds (Sundowners for short) are the northerly gusty winds frequently observed leeward of the Santa Ynez Mountains (SYM) in coastal Santa Barbara (SB), CA. These winds typically peak from early evening through early morning with gale force gusts exhibiting features of downslope windstorms. The SYM rise abruptly from coastal SB separating the Pacific Ocean on its south face from the Santa Ynez Valley on its north face. Sundowners are considered the most relevant fire weather condition in all seasons and represent a major hazard for aviation, particularly small crafts. All major wildfires affecting the region exhibited significant fire spread rates toward the SB wildland-urban interface during Sundowners. The Sundowner Wind Experiment-first intensive campaign (hereafter, SWEX-I) was the first to evaluate vertical profiles of winds, temperature, humidity and other thermodynamic variables from the boundary layer to mid-high troposphere and leeward of the SYM during episodes of Sundowners (wind gusts exceeding 13 m/s or 30 mph). This was accomplished by launching 3-hourly radiosondes during the Sundowner events on April 28-29, 2018. SWEX-I demonstrated that cross-mountain winds in the lee of the SYM exhibit complex spatial and temporal patterns. Profiles of wind speed and direction, temperature and humidity near ground level showed a transition from humid onshore winds from morning-to-mid afternoon hours to very pronounced offshore winds during the evening. These offshore winds accompanied a northerly nocturnal low-level jet leeward of the SYM with variable behavior. The experiment showed evidence of mountain waves and critical layers associated with the intensification of winds. Around sunset (April 28, 20:00 PDT), the jet was characterized by a layer with strong wind speeds (~17m/s) around 273m asl. Winds weakened considerably at 23:00 PDT (peak ~ 9. 5m/s at 186m asl) but enhanced dramatically at 2:00 PDT on April 29 (peak ~14 m/s) at much lower elevations (150asl), when the jet was confined to a much narrower layer compared to observations at 20:00 PDT. These transitions were accompanied by changes in stability profiles and the Richardson number. Additionally, we examined the skill of the Weather and Forecast Model (WRF) (at 1km grid spacing) in forecasting this event, with focus on profiles of winds and stability. These results advanced our understanding of Sundowners and indicated that a comprehensive field campaign is critical to properly characterize the main mechanisms driving these winds and to advance studies on predictability of these events.

Tuesday, 21 August 2018, 3:30 PM Refreshments 3:15 PM NCAR-Foothills Laboratory • 3450 Mitchell Lane • Bldg 2 Small Seminar (Rm1001) Webcast: https://ucarconnect.ucar.edu/live

The Magnetic and Plasma Properties of Coronal Loops

The heating of the solar atmosphere remains to be one of the outstanding questions in Solar Physics. Despite the difficulty in finding a comprehensive and satisfactory explanation (model), significant progress has been made over the years in our understanding of the corona. Our observational constrains to theory and numerics are today far more demanding than simply producing million degree plasma. In this presentation, we discuss the current status of our understanding of the formation and evolution of the building blocks of the atmosphere, coronal loops, looked through the lens of our recent work on the spectroscopic and topological properties of EUV loops, and our efforts to reproduce the data with (Magneto) Hydrodynamic models.

Speaker: Sean Healy

Affiliation: ECMWF

*Please note Special Location- FL2-1001 Small Seminar Room

ECMWF has assimilated GPS radio occultation (GPS-RO) measurements operationally since December 2006, and they are now considered to be a key component of the global observing system. Importantly, these measurements complement the information provided by satellite radiances, because they have good vertical resolution and they can be assimilated without bias correction to the background model. This talk will review how the assimilation of the GPS-RO data at ECMWF has evolved since 2006, and summarise the current impact of this data in the numerical weather prediction system. Current efforts to improve the forward modelling of the GPS-RO data will be described, and areas which require further improvement, such as improved observation error statistics, will be highlighted. Recent wave optics simulation results estimating the size of both the instrument errors and forward model/retrieval errors in the troposphere will be presented.

The importance of GPS-RO measurements for climate reanalyses will be demonstrated. It will be shown that the consistency of ERA5, JRA55 and MERRA-2 temperature estimates in the lower/middle stratosphere has improved since the active assimilation of COSMIC data in 2006.

Refreshments: 3:15pm

Training Workshop: The Community WRF-Hydro Modeling SystemOctober 23-26, 2018 || Boulder, CO

NCAR is pleased to partner with CUAHSI to offer the Training Workshop: The Community WRF-Hydro Modeling System, a 3.5-day hands-on training workshop on the use and applications of the Community WRF-Hydro Modeling System.

Course DescriptionThis training workshop will provide graduate students and early career scientists with formal instruction on the structure and application of the WRF-Hydro system and will offer hands-on experience in setting up and running the system for several different research and prediction applications.

Specific topics to be covered during the workshop include:

• Conceptualization and structure of the WRF-Hydro system
• Description of physics components and options within WRF-Hydro
• Model porting and compilation, and an overview of parallel computing with WRF-Hydro
• Hands-on model input data preparation and creation of an example test case
• Hands-on model configuration and execution
• Hands-on experimental model simulations and comparisons with a prepared example test case
• Overview of the open source Rwrfhydro hydrologic model evaluation package  with example vignettes
• Overview of model calibration
• Overview of data assimilation
• Open discussion on class participant interests and applications

Class participants will receive in-depth training via lectures and hands-on activities on the implementation and use of the WRF-Hydro system where all hands-on tutorial activities will be conducted in a formal computer laboratory located at NCAR in Boulder, CO.

Lead Instructor: Dave Gochis, NCAR

Presenters: Dave Gochis, NCARAubrey Dugger, NCARKevin Sampson, NCARLaura Read, NCARMichael Barlage, NCARArezoo RafieeiNassab, NCARLogan Karsten, NCARJames McCreight, NCARJoe Mills, NCARKatelyn FitzGerald, NCAR

Workshop Eligibility

Applicants must apply to attend the workshop. Applications will be accepted from current and incoming graduate students, post-docs, academics, and professionals working in hydrology and/or the atmospheric sciences. Instructors will review applications to verify in advance that the applicant has the necessary skills and experience to successfully participate in the workshop and get the most out of the course topics. See the event website to apply.

Requirements

• Prior hydrologic and/or atmospheric modeling experience is advised.
• Must be comfortable working in a UNIX environment, running UNIX command line operations and text editors.
• Familiarity with the R and/or Python programming language is recommended.

How to ApplySee the event website to apply. Applications will be accepted beginning June 25, 2018. Complete applications will be accepted on a rolling basis until 5:00 p.m. ET on July 31, 2018. However, we recommend that you submit your application as soon as possible, as applications will be reviewed on a rolling basis on first-come, first-served. We reserve the right to review only the first 50 applications. Past offerings of this course have filled up very quickly.

Visit the event website for additional information on applying to the workshop.