[Dart-dev] [3316] group/posters/trunk: This is the first (and perhaps last) whack at a poster for Hui.

thoar at subversion.ucar.edu thoar at subversion.ucar.edu
Tue Apr 22 17:18:37 MDT 2008


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+\documentclass[landscape,B0]{sciposter}
+%
+% $Id: 2007_AGU_kdr.tex 2904 2007-05-10 00:36:31Z nancy $
+%
+% NEED TO SET TEXINPUTS env variable to have the
+% location of the TeX directory with the style files.
+%
+\usepackage{amsmath}
+\usepackage{amssymb}
+\usepackage{multicol}
+\usepackage[english]{babel}
+\usepackage{graphicx}
+\usepackage{picinpar}
+
+\title{Improving Forecasts of Tropical Cyclones with \\
+       Innovative GPSRO Satellite Observations}
+
+% Note: only give author names, not institute
+\author{H.~Liu, J.~Anderson, Y.-H.~Kuo, Y. ~Chen, and C.~Snyder}
+
+% insert institute name
+\institute{National Center for Atmospheric Research\\
+Institute for Mathematics Applied to Geosciences\\
+Boulder, Colorado, USA}
+
+\email{hliu at ucar.edu}  % shows author email address below institute
+
+% The following commands can be used to alter the default logo settings
+%\leftlogo[1.0]{ncar_logo}     % defines logo to left of title (with scale factor)
+\leftlogo[1.6]{../elements/DARTspaghettiSquare.pdf}
+\rightlogo[1.4]{../elements/imagelogoPoster.pdf}
+
+%===============================================================
+\begin{document}
+%===============================================================
+
+%define conference poster is presented at (appears as footer)
+\conference{28th Hurricane Meeting, April 29-May 2, 2008, Orlando}
+
+\maketitle
+
+\begin{multicols}{4}
+
+% -------------------------------------------------------------------------
+\section{Typhoon Shanshan (2006)}
+% -------------------------------------------------------------------------
+
+The tropical cyclone formed as a tropical depression on September 9, 2006 near 14N, 139E. 
+It went through rapid intensification becoming a Category 4 storm by 12 September, 2006. 
+It then moved northwestward and skirted to the east of Taiwan on 15 and 16 September, 2006.
+It was a challenge to predict the turning of the storm. 
+The typhoon brought heavy rainfall over Taiwan and Eastern China.
+
+\begin{figure}[h]
+\begin{center}
+\includegraphics[height=0.4\columnwidth,angle=0]{best_shan_track.pdf}
+\end{center}
+\caption{Observed best track and intensity of Typhoon Shanshan (2006).}
+\label{fig:best_track}
+\end{figure}
+
+% -------------------------------------------------------------------------
+\section{GPS Radio Occultation (RO) Refractivity observations}
+% -------------------------------------------------------------------------
+\subsection{What is GPS RO refractivity?}
+
+When radio signals from GPS satellites pass through the atmosphere,
+the raypaths are bent and the signal is slowed.
+The changes depend on the atmosphere's density along the path.
+Low-Earth-orbiting (LEO) satellites intercept the signals just above
+Earth's horizon and measure the bend and signal delay.
+The profiles of atmospheric refractivity as a function of height can be derived.  
+
+\begin{figure}[h]
+\begin{center}
+\includegraphics[width=0.7\columnwidth]{../2007_IUGG/Occultation.jpg}
+\end{center}
+\caption{Illustration of Radio Occultation.}
+\label{fig:occultation}
+\end{figure}
+
+\subsection{Reasons to use RO refractivity:}
+
+\begin{itemize}
+\item[$\bullet$] only source of high vertical resolution ($\sim$200m near the surface) 
+                 observations of water vapor for the middle and lower troposphere,
+\item[$\bullet$] provides large-scale observations of water vapor, 
+\item[$\bullet$] is collected under all weather conditions.
+\end{itemize}
+
+\columnbreak
+
+\subsection{Data availability}
+
+\begin{figwindow}[0,r, %
+{\fbox{\includegraphics[height=0.47\columnwidth,angle=0]{gloc13aug.png}}},%
+{Locations of RO profiles over the Western Pacific domain, September 13, 2006.}]
+During 13 September 2006, there were 24 GPS RO refractivity profiles available over the 
+Western Pacific domain. These observations provided large-scale water vapor information.
+\end{figwindow}
+
+\vspace{2.0in}
+  
+% -------------------------------------------------------------------------
+\section{Assimilation Experiments}
+% -------------------------------------------------------------------------
+
+\vspace{0.25in}
+\subsection{WRF/DART Ensemble Assimilation System}
+
+NCAR's Weather and Research Forecast (WRF) model is a state-of-the-art mesoscale
+atmospheric model.  The NCAR WRF/DART (Data Assimilation Research Testbed)
+ensemble data assimilation system 
+is used to assimilate the observations into WRF, which is then run in forecast mode.
+This ensemble-based system is particularly good for mesoscale analysis because 
+weather-dependent (i.e. spatially- and temporally-varying) 
+forecast error covariances are used in the generation of the analysis.
+
+\vspace{0.25in}
+\subsection{Experiments}
+
+Assimilations are done every 6 hours for September 13, 2006 and result in a final analysis
+at 00Z 14 September 2006. WRF is configured to run with 35 vertical levels at 36km
+horizontal resolution with a 120 second timestep.  Thirty-two (32) ensemble members 
+are used for the ensemble assimilation.  Each ensemble member was then run forward to 
+produce a 48-hour forecast. Two sets of nearly identical observations was used to
+determine the impact of the RO refractivity observations.
+
+\vspace{0.25in}
+\subsection{NOGPS}
+
+The following observations were assimilated:
+\begin{itemize}
+\item[$\bullet$] Radiosonde temperature, moisture, and wind vectors (T,Q,U,V),
+\item[$\bullet$] Aircraft temperature and wind vectors (T,U,V),
+\item[$\bullet$] QuikSCAT ocean surface wind vectors (U,V), and 
+\item[$\bullet$] Satellite cloud drift winds (U,V).
+\end{itemize}
+
+\vspace{0.25in}
+\subsection{GPS}
+
+The same observations as NOGPS as well as the RO refractivity observations by
+the COSMIC satellite network.
+
+\vfill
+\columnbreak
+
+% -------------------------------------------------------------------------
+\section{Results}
+% -------------------------------------------------------------------------
+
+\subsection{Impact on track forecast}
+
+The left panel of Figure~\protect\ref{fig:ens_track}, depicts the performance of the
+`NOGPS' experiment. The best track is not in the center of the tracks of the ensemble
+members. The panel on the right is the result of the `GPS' experiment. 
+The ensemble tracks are more symmetrically distributed around the best track and results 
+in an ensemble mean that is much more representative of the Best Track. 
+With the GPS RO observations, the ensemble performs better, especially at the later 
+stage of the forecasts. 
+%The improvement in the storm tracks are due solely to improvements
+%in the analysis field from the GPS RO observations. 
+As the storm matures, the vortex center is more reliably estimated.
+
+\vspace{-0.50in}
+\begin{figure}[h]
+\begin{center}
+\includegraphics[height=0.65\columnwidth,angle=0]{shan_track.pdf}
+\end{center}
+\vspace{-1.0in}
+\caption{Track forecasts for both experiments. 
+The start of the tracks is at 14 Sep 00Z (the end of the data
+assimilation period) and ends at 16 Sep 00Z.
+The position of the vortex center for each 
+ensemble member forecast is depicted as a thin black line. The (observed) Best Track is
+shown in red, the average of the ensemble is shown in green. 
+%The ensemble tracks in the 
+%panel on the right - the experiment with the GPS RO observations - are more 
+%representative of the Best Track.
+}
+\label{fig:ens_track}
+\end{figure}
+
+\subsection{Impact on intensity forecast}
+
+The intensity of the typhoon's minimum central sea level pressure is also
+enhanced (by several hPa) by assimilating the GPS RO observations. 
+The 36km grid size is fundamentally too coarse to accurately represent the storm intensity.  
+
+\vspace{-0.50in}
+\begin{figure}[h]
+\begin{center}
+\includegraphics[height=0.65\columnwidth,angle=0]{shan_int.pdf}
+\end{center}
+\vspace{-1.0in}
+\caption{Ensemble forecasts of the central minimum sea level pressure for 14 Sep 00Z
+through 16 Sep 00Z for both experiments. The assimilations using the GPS RO observations
+result in a slight improvement in intensity.}
+\label{fig:intensity}
+\end{figure}
+
+\subsection{Impact on precipitation forecast}
+
+The GPS experiment forecasts of probability of heavy precipitation over Taiwan more 
+closely match the heavy precipitation that was observed. In general, the GPS experiment
+forecasts have a higher probability of heavy precipitation.
+
+\vspace{-0.50in}
+\begin{figure}[h]
+\begin{center}
+\includegraphics[height=0.65\columnwidth,angle=0]{shan_rain.pdf}
+\end{center}
+\vspace{-1.0in}
+\caption{The two panels on the left show the probability forecast of 24-hour accumulated
+rainfall $>$ 60mm/day during the 24-hour period starting 12Z 14 Aug 2006.
+Note: the panel on the right (showing the observed rainfall) is not to scale with 
+the other two panels in an attempt to highlight the rainfall amounts over 
+northern Taiwan.}
+\label{fig:rainfall}
+\end{figure}
+
+% -------------------------------------------------------------------------
+\section{Conclusion}
+% -------------------------------------------------------------------------
+It can be concluded the GPS RO observations improved the ensemble forecasts of 
+the Typhoon Shanshan. More cases are being studied to evaluate the impact of this 
+new type of satellite observations.
+
+% -------------------------------------------------------------------------
+\section{For further information}
+% -------------------------------------------------------------------------
+
+Our DART web site is: {\bf http://www.image.ucar.edu/DAReS/DART}
+
+There you will find information about how to download the
+latest revision of DART from our subversion server, information
+on a full DART tutorial (included with the distribution), and contact
+information for the DART development group.
+
+\vspace{\baselineskip}
+
+\begin{center}
+\includegraphics[width=4in]{../elements/Dartboard7.png}
+\end{center}
+
+% -------------------------------------------------------------------------
+\begin{thebibliography}{m}
+% -------------------------------------------------------------------------
+
+\bibitem{areference}
+R.A.~Anthes et.al., 2008: 
+{The COSMIC/FORMOSAT-3 Mission: Early Results} {\it BAMS},
+          {\bf 89} No. 3 pp. 313--333
+
+\end{thebibliography}
+
+\end{multicols}
+\end{document}
+

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