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Unless noted otherwise, all seminars take place at:
NOAA Center for Weather and Climate Prediction
5830 University Research Court
College Park, MD  20740

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If you are a presenter and are going to be giving a JCSDA seminar with slides, please follow these guidelines on presentation file preparation.

Upcoming JCSDA Seminars

About JCSDA's Seminar Series

The JCSDA seminar series includes presentations on satellite observing instruments, radiative transfer models for use in satellite data assimilation, algorithms for deriving information on the Earth's atmosphere, oceans, and land surface from satellite observations, advances in data assimilation techniques, preparations for assimilation of data from new satellite instruments, and impacts of satellite data on weather and climate predictions. The seminars are about 1 hour in duration (including discussion period) and are held monthly, usually on the 3rd Wednesday of each month at 2 PM, and are open to the public.

The audience for the seminars generally consists of remote sensing researchers from NOAA/NESDIS, data assimilation experts and modelers from NOAA/NCEP and NASA/Goddard Space Flight Center Global Modeling and Assimilation Office, and students/faculty from the University of Maryland.

  • Slides for each presentation should be available for download in PDF format on this page, the day before each talk.
  • Unless specifically noted otherwise, the contact for the JCSDA seminar series is Kevin Garrett.

Upcoming Seminars


Title

Correcting for Position Errors in Variational Data Assimilation

Presentation file posted here when available.

Speaker Thomas Nehrkorn
AER
Date Monday, November 10, 2014
2:00 p.m. - 3:00 p.m.
Conference Center, NOAA Center for Weather and Climate Prediction,5830 University Research Court, College Park, MD
Abstract

Show Abstract

Forecasts used in variational data assimilation schemes for the atmosphere and ocean often exhibit significant position errors. In standard data assimilation approaches position errors often result in background errors that have complex error correlations, are not normally distributed, and are particularly difficult to correct. A number of approaches have been proposed to measure and correct position or phase errors, ranging from techniques originating from image processing such as "image warping" or "morphing" and "optical flow," object-oriented verification measures, to alignment approaches aimed at data assimilation improvements.

We present an implementation of a displacement scheme to correct phase errors based on the feature calibration and alignment (FCA). In its original formulation, a set of two-dimensional displacement vectors is applied to forecast fields to improve the alignment of features in the forecast and observations. These displacement vectors are obtained by a nonlinear minimization of a cost function that measures the misfit to observations, along with a number of additional constraints (e.g., smoothness and non-divergence of the displacement vectors) to prevent unphysical solutions. Results from this implementation will be compared with a more recent implementation within the WRF-Var (WRFDA) algorithm, in which the nonlinear minimization is replaced by the (linear) conjugate gradient inner-loop minimization combined with outer loop nonlinear adjustments, and the ad-hoc penalty function constraints are replaced by an error-covariance representation of the displacement vectors.

Remote Access Video: 1. Go to JCSDA Seminar and click on the seminar title
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Audio: USA participants: 1-866-715-2479, Passcode: 9457557
International: 1-517-345-5260
Contact

Erin Jones




Most seminars are scheduled on Wednesdays at 2:00 p.m. unless noted otherwise. Titles are tentative, and are subject to change.

Modified February 12, 2014 11:02 PM
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