Real-time Doppler winds
Vijay Tallapragada (NCEP/EMC)
Mingjing Tong (NCEP/EMC)
Alan Goldstein (NMAO/AOC)
Fuging Zhang (Penn State)
Yonghui Weng (Penn State)
- To control the quality of airborne Doppler radar data in "real time."
- To analyze the quality-controlled data in "real time."
- To deliver the data and analyses in 'real time' to the Environmental Modeling Center and National Hurricane Center.
- To examine how these data may be incorporated into numerical simulations.
- To determine the best flight strategies for obtaining data that will initialize the simulations.
Rationale and Methodology:
As operational hurricane forecasts attain finer resolution, the models must be initialized with finer-resolution data. Airborne Doppler radar observations provide the most widespread observations of the hurricane core at a 1.5-km resolution. At the Hurricane Research Division we have been developing methods to produce research-quality analyses from the airborne Doppler radar aboard the NOAA WP-3D (P-3) aircraft for 30 years. Within the last decade we have been refining a three-dimensional variational method to produce three-dimensional wind analyses, as well as analyses of winds in a vertical cross-section defined by the flight track of the aircraft. Coarser-resolution three-dimensional, as well as same-resolution vertical cross-sections, and now produced routinely in "real time." The three-dimensional analysis scheme was described by Gamache et al. (1997), and has been modified in such a way as to be nearly identical to the method described by Gao et al. (1999). The variational scheme simultaneously minimizes
- the difference between the projection of the wind analysis on the Doppler radial direction cosines, and the observed Doppler radial velocities,
- the error in the 4-th order discretized three-dimensional mass divergence of the wind field, and
- the various second derivatives of wind components.
- Real-time QC and analysis method tested successfully on NOAA P-3 aircraft in 2004 (not transmitted).
- Doppler analyses transmitted to NHC in real time in 2005 (in particular in Wilma of October 2005)
- Real-time quality controlled analyses of airborne Doppler radar data accepted by JHT (NHC) for operational use.
- Real-time analyses transmitted in real time from Tropical Storm Ernesto and Hurricane Helene of 2006, and routinely since them.
- Doppler-radar superobs (intelligently averaged Doppler velocities designed to reduce number of observations that must be assimilated) transmitted to ground beginning in Tropical Storm Fay (2008) and routinely thereafter. Superobs were assimilated in "real time" into a research WRF-ARW tropical-cyclone simulation.
- Quality-controlled P-3 Doppler radials first assimilated in a "real-time" parallel run of the operational HWRF in Hurricane Tomas of (2010)
- A simple GUI menu was developed to help set up parameters for automatic quality control and analysis. Recently, during 2013-2014, this has been adapted to a java application that can be run across many platforms, allowing numerous HRD personnel to submit real-time QC and analysis runs to the linux system running aboard the aircraft.
- RVP-8 (Sigmet radar data system now on both P3's as well as the G-IV) I/O software developed and first TC-run performed on data collected in Hurricane Katia (2011).
- Quality-controlled P-3 Doppler radials first assimilated in operational HWRF run during Hurricane Ingrid of 2013.
- Deploy new job-file submission for airborne real-time airborne-Doppler quality control and analysis aboard all three NOAA aircraft with airborne Doppler radars.
- Assimilate quality-controlled G-IV airborne Doppler radial velocities in parallel real-time HWRF runs, and if possible the operational HWRF.
- Bargen, D. W., and R. C. Brown, 1980:Interactive radar velocity unfolding. Proc. 19th Conference on Radar Meteorology, Miami, Amer. Meteor. Soc., 278-283.
- Gamache, J. F., 1997: Evaluation of a fully three-dimensional variational Doppler analysis technique. Preprints, 28th Conf. On Radar Meteorology , 9-13 Sept. 1997, Austin, AMS.
- Gamache, J. F., 2005:Final report on JHT project entitled: Real-Time Dissemination of Hurricane Wind Fields Determined from Airborne Doppler Radar.
- Gao Jidong, Ming Xue, Alan Shapiro, Kelvin K. Droegemeier, 1999: A Variational Method for the Analysis of Three-Dimensional Wind Fields from Two Doppler Radars. Mon. Wea. Rev: 127, 2128-2142.
- Zhang, Fuqing, Yonghui Weng, John F. Gamache, and Frank D. Marks, 2011: Performance of convection-permitting hurricane initialization and prediction during 2008-2010 with ensemble data assimilation of inner-core airborne Doppler radar observations. Geophys. Res. Lett., 38, L5810, 1-6.
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