Staff Notes Daily Calendar Events

Title: Seasonal Climatology, Variability, and Temporal Characteristics of Caribbean Rainfall

Speaker: Carlos Martinez, Columbia University

Date: Tuesday 26 January 2021

Time: 11 am - 12 pm

To join via Zoom contact Tracy Baker, tbaker@ucar.edu

Abstract: The Caribbean is a topographically complex region that heavily relies on its rainfall cycle for its economic and societal needs. This makes the Caribbean especially susceptible to hydro-meteorological disasters (e.g., droughts and floods). Previous studies have investigated the seasonal cycle and variability of rainfall in the Caribbean with monthly or longer resolutions that often mask the seasonal transitions and regional differences of rainfall. In addition, temporal characteristics (e.g., onset, demise), which are useful for farmers, have yet to be investigated. To address this, the study conducts principal component, moisture budget, and composite analyses to better understand the Caribbean rainfall cycle and its variability using 38 rain gauges and ERA-Interim Reanalysis over the region. The seasonal climatology of Caribbean rainfall hinges on two main facilitators of moisture convergence: the Intertropical Convergence Zone and the North Atlantic Subtropical High, and two regional modifiers of moisture convergence: the Atlantic Warm Pool, and the Caribbean Low-Level Jet. The spatial and temporal evolution of these dynamical mechanisms vary across the five regions of the Caribbean. The early and late rainfall seasons of the Caribbean are impacted in distinctly different ways by two different, and largely independent large-scale phenomena: the North Atlantic Oscillation, and the El Niño-Southern Oscillation, respectively. Onsets and demises that are calculated based on yearly rainfall seasonal means effectively characterize the seasonal evolution of mean onsets and demises in the Caribbean. Onsets and demises that are calculated based on the climatological seasonal mean resemble the variability of seasonal rainfall totals in the Caribbean. The study has important implications for prediction of rainfall and modeling capabilities.

For more information contact Tracy Baker, tbaker@ucar.edu

Title: The challenge of energy budget closure in Earth system models

Speaker: Peter Lauritzen, NCAR

Date: Tuesday 16 March 2021

Time: 11 am - 12 pm

For zoom information please contact Tracy Baker, tbaker@ucar.edu

Abstract:  A closed total energy (TE) budget is of utmost importance in coupled climate system modeling. In the case of the atmosphere it involves physical parameterizations, the dynamical core solver, the coupling between the two (referred to as physics-dynamics coupling) and fluxes from the surface components. The budget is rather complicated partly due to the fact that all parts of an Earth System Model are involved and, even on a continuous level, it is not straightforward how to formulate energetically and thermodynamically consistent equations for a moist atmosphere containing falling hydrometeors.A detailed analysis of the spurious sources/sinks of TE in the National Center for Atmospheric Research's Community Atmosphere Model (CAM) is given. This includes spurious sources/sinks associated with the parameterization suite, the dynamical core, TE definition discrepancies, and physics‐dynamics coupling. It will also be discussed how to move towards a more comprehensive and thermodynamically consistent formulation of TE in CAM.

For more information contact Tracy Baker, tbaker@ucar.edu, 303-497-1366

SPEAKER:      Chris Rattray - Masters Student, School of Meteorology, University of Oklahoma

DATE:              January 19, 2021

TIME:               3:30 - 4:30 pm

WEBCAST:     operations.ucar.edu/live-eol (Will be recorded and uploaded to the EOL Youtube channel)

QUESTIONS:  During the seminar, you will have the opportunity to ask questions via Slido

ABSTRACT

This study investigates the evolution of the Great Plains nocturnal low-level jet (NLLJ) as warm, moist flow returns following a cold frontal passage. The study utilizes the ERA-5 reanalysis and 3-h radiosonde data taken during the International H2O Project field campaign. This talk will present new insight into the processes controlling the NLLJ intensity and structure including the possible role of variations in water vapor and radiative processes. The results also show that two mechanisms resulted in the destabilization of the nocturnal environment, weak (2 cm/s) ascent and differential advection, with implications for the eastward movement of nocturnal convection over the region.

If you have any questions about the seminar, reach out to Jacquie Witte or Melissa Ward.

From solar atmosphere to tokamak divertor: plasma diagnostics and spectroscopic techniques

The emission of photons and all spectral lines have encoded information to diagnose the physical and chemical status of the emitting source, carrying the signature of the underlying plasma parameters. Such an approach is suitable not only in an astrophysical context, but also for laboratory fusion plasmas. Atomic physics provides the link that enables the observed spectra to be interpreted in terms of the properties of the source from which they arise, whether they originate in an experiment on Earth, such as a laser or tokamak device, or in an astronomical object, ranging from the Sun and stars to planetary nebulae and interstellar medium. The increasing capabilities of the current and new space-borne instrumentation (e.g. Interface Region Imaging Spectrograph, Solar Orbiter, Parker Solar Probe) and controlled fusion devices (e.g. Mega Ampère Spherical Tokamak Super-X upgrade divertor, International Thermonuclear Experimental Reactor, Spherical Tokamak for Energy Production, DEMOnstration Power Station), require atomic modelling and the derived spectroscopic techniques to be regularly revised and upgraded. The present work will strongly exploit this interdisciplinary link between laboratory and astrophysics plasma environments. Atomic data requirements and their accuracy will be discussed, concentrating on the applications to the analysis of the solar upper atmosphere emission and the investigation of controlled fusion plasmas in a tokamak divertor. An example of the exploitation of a common methodology for the detection and assessment of non-equilibrium processes will be described. This will show that the derived atomic data allow equivalent prediction in non-stationary transport regimes and dynamic conditions of both the solar atmosphere and tokamak divertor.

https://meet.google.com/idt-ncsy-sfq

Understanding solar wind formation by identifying the origins of in situ observations

Authors: S. Wallace, C.N. Arge, N.M. Viall, S. Di Matteo, S.I Jones

Solar wind formation can be separated into three physical steps – source, release, and acceleration -- that each leave distinct observational signatures on plasma parcels. The Wang-Sheeley-Arge (WSA) model driven by Air Force Data Assimilative Photospheric Flux Transport (ADAPT) time-dependent photospheric field maps now has the ability to connect in situ observations more rigorously to their precise source at the Sun, allowing us to investigate the physical processes involved in solar wind formation. In this talk, I will highlight my PhD dissertation research in which we use the ADAPT-WSA model to either characterize the solar wind emerging from specific sources, or investigate the formation process of various solar wind populations. In the first study, we test the well-known inverse relationship between expansion factor (fs) and observed solar wind speed (vobs) for solar wind that emerges from a large sampling of pseudostreamers, to investigate if field line expansion plays a physical role in accelerating the solar wind from this source region. We find that there is no correlation between fs and vobs at pseudostreamer cusps. In the second study, we determine the source locations of the first identified quasiperiodic density structures (PDSs) inside 0.6 au. Our modeling provides confirmation of these events forming via magnetic reconnection both near to and far from the heliospheric current sheet (HCS) -- a direct test of the Separatrix-web (S-web) theory of slow solar wind formation. In the final study, we use our methodology to identify the source regions of the first observations from the Parker Solar Probe (PSP) mission. Our modeling provided confirmation that the closest to the Sun observed coronal mass ejection (CME) to date was a streamer blowout. We close with future ways that ADAPT-WSA can be used to test outstanding questions of solar wind formation.

meet.google.com/idt-ncsy-sfq

Are you interested in K-12 education and public outreach? If so, please join your colleagues in an online Zoom discussion about this topic on Tuesday, January 26 from 2:30-3:30 pm. During this meeting, we will share updates on education and outreach efforts happening across the organization, discuss ideas for collaborations across groups, and discuss new ideas for education and outreach efforts we want to consider doing in the future.

To RSVP, please send an email to Shaun Bush at sbush@ucar.edu and you'll be added to the calendar invite.

If you would like to discuss or share anything at the meeting, please add it to our agenda. This is a living document that you can fill out before and during the meeting.

In addition, if you haven't already signed up for the email list for this group (k12@ucar.edu), please email Emily Snode-Brenneman at emilysb@ucar.edu and let her know that you would like to be added to the list to get notifications about education and outreach opportunities.

We hope to see you at the meeting!

Eric Gilleland - National Center for Atmospheric Research

Spatial forecast verification has exploded into an increasingly complicated set of tools for either automatically assessing forecast performance or providing diagnostic plots and other information.  A set of tools that breaks that mold by providing simple, easy-to-understand summary measures has also gained some traction in recent years, and are now included, for example, in the MET software.  No single summary will provide all the information needed and each will have its pros and cons.  Recent work has demonstrated some common pitfalls with each of them.  Predicated off of this work, a new summary measure is proposed that does not suffer from any of these flaws, while providing useful information about forecast performance.

Thursday, February 18, 2021 | 1:00 PM - 2:00 PM

Live webcast - https://operations.ucar.edu/live-ral

Thursday, January 28, 2021

Consultant:

Rhet Belcher

9:00am - 4:00pm

For more information, contact hopek@ucar.edu