The Advanced Dvorak Technique (ADT) utilizes longwave-infrared, temperature
measurements from geostationary satellites to estimate tropical cyclone (TC) intensity.
The ADT is based upon the operational
developed by Vern Dvorak of NOAA over 30 years ago. This step-by-step
technique relies upon the user to determine a primary cloud pattern and measure
various TC cloud top parameters in order to derive an initial intensity estimate. Various
rules regarding TC development and intensity change over time are employed to guide
the user in the scene selection process and govern the rate in intensity change over a
given time period.
The Dvorak Technique continues to be the standard method for estimating TC intensity where
aircraft reconnaissance is not available (all tropical regions outside the North Atlantic
and Caribbean Sea), however it has several important limitations and flaws. The primary
issue centers upon the inherent subjectivity of the storm center selection and scene type
determination proceedures. Secondly, learning the Dvorak Technique and its regional nuances
and adjustments can take a significant time to master. Finally, the technique was developed
more or less empirically by Dvorak and his colleagues, without the aid of computer analysis,
to determine statistical relationships between various environmental parameters and intensity.
The ADT (and its predecessors the ODT and AODT) sought to alleviate many of the limitations
found within the Dvorak Technique and previous objective algorithms based upon methods
outlined by Dvorak. The ADT currently utilizes an objective storm center determination
scheme and cloud pattern determination logic to remove the subjectivity aspect from the
intensity estimation process. It also can be applied to all phases of the TC lifecycle;
something that previous objective schemes could not do. Finally, the ADT makes use
of statistical analysis results obtained from a 10+ year sample of North Atlantic storms, along
with a significant sample of West and East Pacific storms, covering the entire spectrum of
TC intensities to derive a regression-based intensity value estimate for various phases
of the TC lifecycle.
The ADT is a powerful but easy-to-use TC intensity estimation guidance tool
possessing an accuracy on par with estimates obtained by experienced TC forecasters
using the Dvorak Technique.
Link to real-time ADT estimates here.
ADT flowcharts :
Scene Selection |