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Objective Dvorak Technique (ODT) AFWA/XOGM. Material for this training module largely comes from:. UW-CIMSS Objective Dvorak Technique. Tim Olander and Chris Velden University of Wisconsin - Madison Cooperative Institute for Meteorological Satellite Studies In cooperation with :

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Objective Dvorak Technique (ODT)AFWA/XOGM


Uw cimss objective dvorak technique

Material for this training module largely comes from:

UW-CIMSS Objective Dvorak Technique

Tim Olander and Chris Velden

University of Wisconsin - Madison

Cooperative Institute for Meteorological Satellite Studies

In cooperation with :

Jeff Hawkins

Naval Research Laboratory - Monterey, CA

Office of Naval Research


Objective Dvorak Technique (ODT)

Overview

- What is the ODT?- How does it work?- Why use it?- How will we use it here?


Objective Dvorak Technique (ODT)

What is the ODT?ODT is a computerized method for determining the intensity of tropical cyclones. It was originally developed by the University of Wisconsin, and we are able to perform some ODT functions currently.Ok, so how does it work?



Odt methodology1

Identification of two environmental temperatures (BTs)

Uses IR data only

Eye Temperature (0-40 km)

Cloud Temperature (26-136 km)

Scene identification performed

ODT is only performed for four types of features:

Eye, Embedded Center, CDO, and Shear

SIDAS version only handles EYE currently

Based on histogram and Fourier Transform Analysis

ODT Methodology


Odt methodology2

Determination of the cloud pattern is performed objectively (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

ODT Methodology


Odt methodology3

Storm Center Location (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

The only user input is the specification of the storm center location

ODT only does intensities

EYE determination

If the storm has an eye, it uses the warmest pixel temperature within a 40 km radius of the chosen storm center

Warm values represent ocean surface or low cloud within the eye

This value is retained as the 'eye temperature'.

ODT Methodology


Odt methodology4
ODT Methodology (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


Warmest value = 'eye temperature' (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


Odt methodology5

EYE determination (con’t) (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

ODT analyzes temperatures on concentric rings (1 pixel wide) centered on the eye between 24 km and 136 km from the eye location (this range was empirically determined by many observations of coldest ring radii).

For GOES data with 4km pixel resolution, this results in a total of 28 rings that are analyzed to determine the 'surrounding temperature'.

In addition, a continuous ring of cold temperatures surrounding the eye is more indicative of an organized (and more intense) storm than one with breaks in the convection.

Therefore, the warmest temperature found on each ring is identified and stored, with the coldest of these retained as the final surrounding temp value.

ODT does not reposition the storm center, since it has been found that the subsequent analysis of the surrounding temperature field may be improperly influenced by this adjustment in some cases ('false' eyes).

ODT Methodology


Odt methodology6
ODT Methodology (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


Odt methodology7
ODT Methodology (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


Odt methodology8
ODT Methodology (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

The warmest temperature

is found on each ring...


Odt methodology9
ODT Methodology (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

This ring has “Light Grey”

as its warmest temp.


Odt methodology10
ODT Methodology (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

Of those temps that are

left, the coldest is taken

as the surrounding ring


Odt methodology11

“No Eye” Condition (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

ODT can handle Central Dense Overcast (CDO)/Embedded Center

Temperatures near the storm center are dominated by cold cloud tops and a warm eye is not resolvable.

The value of the pixel at the user-defined storm center location is used as the 'eye’ temperature

Shear scenario is also detected in ODT

The SHEAR, CDO/EMBD CTR ARE NOT YET AVAILABLE IN SIDAS VERSION OF SOFTWARE

ODT Methodology


Odt methodology12

Initial intensity estimate determined (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.(Raw T#)

Based on original Dvorak Rules for different patterns and cloud top temperatures. Eye temperature serves as adjustment

Use history file with previous storm analysis data

(Final T#)

Provide data for 12-hour time weighted time averaging scheme

This means we have to perform ODT every hour

Data is saved in SIDAS interface

Implementation of Dvorak Rule 9 for weakening storms (CI#)

Corrects underestimate bias in weakening storms

Hold T# constant for 12 hours after initial weakening, add 1.0 T# until dissipation or restrengthening

Not currently implemented in SIDAS

ODT Methodology


Odt purpose
ODT Purpose (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

  • Ok, but why use it?

  • 1. It’s OBJECTIVE

    • Doesn’t depend on opinions of human being

    • Done the same way every time

    • Can be more accurate (sometimes)

  • 2. It’s FAST

    • Computer derived

    • Some storms are harder than others

  • 3. It’s WANTED

    • JTWC has formally requested that we do this

    • We are holding off until full capability is here

    • Test mode only for now


  • Current user status

    Operational Use (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    NOAA/NESDIS Satellite Analysis Branch

    NHC/Tropical Analysis Forecast Branch

    Experimental Use

    Joint Typhoon Warning Center

    Air Force Weather Agency

    Central Pacific Hurricane Center

    Australian Bureau of Meteorology

    Japanese Meteorological Agency

    Current User Status


    Odt past performance

    Developmental Data Sample (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    1995-1997

    Independent Data Sample

    1998-1999

    Units in hPaBiasRMSESample

    ODT +1.69 7.34 407

    Op. Center +4.31 10.35 407

    Units in hPaBiasRMSESample

    ODT -0.72 7.97 397

    Op. Center -0.05 10.38 397

    Units in hPaBiasRMSESample

    TAFB +2.29 10.76 305

    ODT +1.58 7.46 305

    SAB +4.88 10.42 319

    ODT +1.45 7.35 319

    AFWA +5.55 12.06 146

    ODT +0.53 7.39 146

    Units in hPaBiasRMSESample

    TAFB -1.25 10.65 341

    ODT -0.62 8.72 341

    SAB +0.58 9.91 334

    ODT -0.53 8.75 334

    AFWA +1.83 10.40 334

    ODT -0.43 8.07 334

    ODT Past Performance

    Legend : TAFB - Tropical Analysis Forecast Branch - NOAA/NCEP

    SAB - Satellite Analysis Branch - NOAA/NESDIS

    AFWA - U.S. Air Force Weather Agency


    Super typhoon bilis 18w
    Super Typhoon Bilis (18W) (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    http://pzal.npmoc.navy.mil/jtwc_archive/2000/STORM_FOLDERS/NORTHWEST_PACIFIC/18W/Time_Intensity_Chart/18W_ti.gif

    • Good agreement with operational center and Best Track estimates

      • Slight overestimate during intensification and at peak

      • CI#s compare better with Best Track during weakening than Final T#s

      • Rapid weakening indicated by Final T#s supported by AMSU data (landfall)

      • SAB ODT estimates differ from JTWC ODT during intensification


    Super Typhoon Saomai (22W) (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    http://pzal.npmoc.navy.mil/jtwc_archive/2000/STORM_FOLDERS/NORTHWEST_PACIFIC/22W/Time_Intensity_Chart/22W_ti.gif

    • Good agreement with operational center and Best Track estimates

      • Underestimate during weakening with Final T#s (should use CI#s)

      • Initial estimates off due to very cold cloud top temperatures (~-80ºC)

      • SAB ODT analysis very similar to JTWC ODT analysis


    Super Typhoon Shanshan (26W) (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    http://pzal.npmoc.navy.mil/jtwc_archive/2000/STORM_FOLDERS/NORTHWEST_PACIFIC/26W/Time_Intensity_Chart/26W_ti.gif

    • Slight disagreement with operational center and Best Track estimates

      • Over/Underestimate during strengthening/weakening processes

      • CI#s compare better with Best Track during weakening than Final T#s

      • Rapid intensification cycles noted but led to ODT overestimates

      • SAB ODT analysis very similar to JTWC ODT analysis


    Summary and conclusions

    6 storm sample for 2000 West Pacific season (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    Overall, good comparison between JTWC and SAB ODT estimates

    JTWC and SAB ODT Final T# estimates were typically within 0.5 T# of JTWC Best Track estimates

    Very cold cloud temperatures led to high bias in Final T# relative to JTWC Best Track estimates (cloud temperatures < upper -70°C)

    Rapid intensification flag correctly identified events but led to large Final T# high bias when coupled with very cold cloud top temperatures (tuning to West Pacific needed)

    Slight differences between JTWC and SAB ODT estimates

    Possible errors with ocean basin identification (basin flag is manually adjusted; could be automated)

    Implementation of 48 Hour Rule is slightly different between JTWC and SAB due to different ODT versions (fixed vs. time-weighted value)

    Overall, CI#s provided better fit to JTWC Best Track estimate than Final T#s during weakening

    Summary and Conclusions


    Future directions

    Operational ODT Usage (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    Full operational test at JTWC during 2001 with devoted analyst (patterned after SAB and TAFB evaluation)

    Experimental use only here at AFWA

    Research Focus

    Further tune ODT for West Pacific based on JTWC and SAB 2000 results

    Expand analysis range for tropical storms and weaker systems (will remove need for 48 Hour Rule)

    Investigate application of rapid intensification flag based on user analysis and feedback

    Begin development of Multispectral Dvorak Technique (MDT), incorporating multiple satellite and channel information(AMSU, SSM/I, visible, water vapor, etc.)

    Future Directions


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    • JTWC uses it on NSDS-E

    • SAB uses it in MCIDAS

    • How will we use it here?

      • SIDAS

      • New Eye Intensity Calculation

        ODT IS ALWAYS TO BE PERFORMED AFTER YOU COMPLETE YOUR OWN INDEPENDENT ANALYSIS!


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    Previous

    SIDAS

    Method

    ODT Method


    Odt methodology13
    ODT Methodology (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    ODT uses rings….


    Previous sidas method
    Previous SIDAS Method (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    The SIDAS method uses

    radial measurements of

    temperature. ODT and

    SIDAS are different!

    Neither include

    any banding features!


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    The SIDAS method

    is only for a “point

    in time”. The ODT

    is time averaged.

    ~

    So…..we need to

    save this ODT

    calculation……..

    Hit the button


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    Once you hit

    the button,

    the names of

    all available

    ODT storm

    archives will

    appear

    Hit the button:


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    Highlight the

    ODT storm

    archive file

    that you need


    Highlight the (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    ODT storm

    archive file

    that you need

    ODT Implementation

    Then Hit

    the button:


    ODT Implementation (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.

    Remember that

    you will need to

    do this every hour

    (while the storm

    has an EYE!)


    Questions? (in other words, by the computer) by examining area histograms of cloud top temperatures and corresponding Fourier Analysis for the eye region and surrounding cloud region. Based on this analysis, four scene patterns can be categorized by ODT: Eye, Central Dense Overcast, Embedded Center, and Shear.Objective Dvorak Technique (ODT)AFWA/XOGM


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