Follow the instructions that appear on your screen.
Audio / conference call:
USA participants: 1-866-715-2479
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.
Correcting for Position Errors in Variational Data Assimilation
Presentation file posted here when available.
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
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
Video: 1. Go to JCSDA Seminar and click on the seminar title
2. Enter your name and email address.
3. Click "Join Now".
4. Follow the instructions that appear on your screen. Audio: USA participants: 1-866-715-2479, Passcode: 9457557