1. FY10-11 GIMPAP Project Proposal Title Page

1. 1. FY10-11 GIMPAP Project Proposal Title Page • Title: Improvements to the Advanced Dvorak Technique (ADT) • Project Type: Product Improvement • Status: New – continuing work from GIMPAP FY08-09 project • Duration: 2 Years • Leads: • Chris Velden (CIMSS) • Tim Olander (CIMSS) • Other Participants: • Mike Turk (NOAA/NESDIS/SAB)

2. 2. Project Summary • A new concept using multispectral geostationary satellite data has been recently developed, and a journal article accepted for publication – Olander, T. and C. Velden, 2009: Tropical cyclone intensity and convection analysis using differenced Infrared and Water Vapor imagery. Accepted in Wea. And Forecasting. • We propose to investigate these ideas towards potential applications to the Advanced Dvorak Technique, an operational objective algorithm that estimates tropical cyclone intensity.

3. 3. Motivation/Justification • Supports NOAA Mission Goal(s): Climate, Weather and Water • NOAA/NWS has declared that Tropical Cyclone intensity analysis and forecasting improvement is a high priority research goal • The ADT is now an established operational TC intensity estimation algorithm used by NOAA/NESDIS to support hurricane analysis, however, the method’s accuracy in certain conditions is still suboptimal • We continue to strive to improve the ADT performance through new innovations, that when successful can be transitioned to the operational version • One such new innovation we propose to investigate is a new product that we think might lead to improved ADT performance

4. 4. Methodology • The proposed technique highlights the spectral response differences between geostationary infrared window (IRW) and water vapor (WV) channel data in regions of intense TC convection. As noted in standard tropical atmosphere weighting functions, the WV will typically be colder than the IRW during tropospheric clear sky conditions. However, in opaque cloud conditions associated with intense, active convection penetrating the tropopause, the sign of the measured difference between the two channels can reverse due to the re-emitted radiation from above-cloud water vapor at higher stratospheric temperatures. • The initial Olander and Velden study suggests that the IRWV product values can be used in a variety of ways to provide TC forecasters with important information about current and future intensity trends. The derived imagery may aid in the TC storm center identification process, both manually and objectively, especially in difficult situations where the IRW imagery alone cannot be used such as when the storm circulation center and/or eye feature are obscured by a cirrus canopy. Quantitative methods discussed in the study involve the predictive quality of the IRWV data in terms of TC intensity changes, primarily during TC intensification. Strong correlations exist between storm intensity change and IRWV values at varying 6-hr forecast interval periods, peaking between the 12-hour and 24-hour time periods. Implications of the IRWV data as a potential input parameter to the ADT will be the primary focus of the proposed work.

5. Cross section of GOES-12 brightness temperatures (Tb) during Hurricane Wilma (2005) near the time of its maximum intensity on 19 October/09:15UTC. The west to east cross section transverses the eyewall as well as the outer rainbands of the storm. In the outer regions of the TC, the clouds are typically less opaque or missing entirely, resulting in brightness temperature measurements in line with those expected; WV Tbs (red) are colder than the corresponding IRW values (blue). In the inner eyewall region, however, this relationship reverses as water vapor above the convection is forced through the tropopause and into the stratosphere where it re-emits in the WV emission bands at higher temperatures. Here, the IRW minus WV (IRWV) difference values are near zero or negative, indicating the presence of vigorous convection “overshooting” into the stratosphere. . .

6. 5. Expected Outcomes • If the research is successful and validated, we will see an improved performance in the ADT algorithm’s ability to estimate tropical cyclone intensity • A GOES PSDI proposal will be submitted to implement the new science into the existing operational version of the ADT

7. 6. FY10-11 Milestones • Jan – July 2010 • Explore the new concepts as potential input to the ADT • Build a large GOES dataset for interrogation (Atlantic tropical cyclone cases with aircraft validation) • July – Dec 2010 • Implement the new science upgrades into the experimental ADT version at CIMSS for testing and evaluation • Begin experimentation on dependent dataset • Jan – July 2011 • Continue ADT experimentation and conduct statistical evaluation and error analysis • July – Dec 2011 • Conduct real time test of upgraded ADT version on 2011 Atlantic tropical cyclones • Provide final report and analysis; recommend for operational transition

8. 7. Funding (K)