Detecting the Intensity Evolutions of Northwest Pacific Super Typhoons in 2015 Using Deviation Angle Variance Technique

2018 ◽  
Vol 07 (06) ◽  
pp. 430-441
Author(s):  
猛 袁
Keyword(s):  
Northwest Pacific ◽  
Deviation Angle ◽  
Variance Technique

scholarly journals Tropical Cyclogenesis Detection in the North Pacific Using the Deviation Angle Variance Technique

2015 ◽  
Vol 30 (6) ◽  
pp. 1663-1672 ◽  
Author(s):  
Kimberly M. Wood ◽  
Oscar G. Rodríguez-Herrera ◽  
Elizabeth A. Ritchie ◽  
Miguel F. Piñeros ◽  
Ivan Arias Hernández ◽  
...  
Keyword(s):  
False Alarm ◽  
False Alarm Rate ◽  
Tropical Cyclones ◽  
Median Time ◽  
North Pacific ◽  
Western North Pacific ◽  
Tropical Cyclogenesis ◽  
Deviation Angle ◽  
Variance Technique ◽  
Cloud Clusters

Abstract The deviation angle variance technique (DAV-T) for genesis detection is applied in the western and eastern North Pacific basins. The DAV-T quantifies the axisymmetric organization of cloud clusters using infrared brightness temperature. Since axisymmetry is typically correlated with intensity, the technique can be used to identify relatively high levels of organization at early stages of storm life cycles associated with tropical cyclogenesis. In addition, the technique can be used to automatically track cloud clusters that exhibit signs of organization. In the western North Pacific, automated tracking results for the 2009–11 typhoon seasons show that for a false alarm rate of 25.6%, 96.8% of developing tropical cyclones are detected with a median time of 18.5 h before the cluster reaches an intensity of 30 knots (kt; 1 kt = 0.51 m s−1) in the Joint Typhoon Warning Center best track at a DAV threshold of 1750°2. In the eastern North Pacific, for a false alarm rate of 38.0%, the system detects 92.9% of developing tropical cyclones with a median time of 1.25 h before the cluster reaches an intensity of 30 kt in the National Hurricane Center best track during the 2009–11 hurricane seasons at a DAV threshold of 1650°2. A significant decrease in tracked nondeveloping clusters occurs when a second organization threshold is introduced, particularly in the western North Pacific.

Tropical Cyclone Intensity Estimation in the North Atlantic Basin Using an Improved Deviation Angle Variance Technique

2012 ◽  
Vol 27 (5) ◽  
pp. 1264-1277 ◽  
Author(s):  
Elizabeth A. Ritchie ◽  
Genevieve Valliere-Kelley ◽  
Miguel F. Piñeros ◽  
J. Scott Tyo
Keyword(s):  
Root Mean Square ◽  
North Atlantic ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Mean Square ◽  
Deviation Angle ◽  
The North ◽  
Variance Technique ◽  
The North Atlantic

Abstract This paper describes results from an improvement to the objective deviation angle variance technique to estimate the intensity of tropical cyclones from satellite infrared imagery in the North Atlantic basin. The technique quantifies the level of organization of the infrared cloud signature of a tropical cyclone as an indirect measurement of its maximum wind speed. The major change described here is to use the National Hurricane Center’s best-track database to constrain the technique. Results are shown for the 2004–10 North Atlantic hurricane seasons and include an overall root-mean-square intensity error of 12.9 kt (6.6 m s−1, where 1 kt = 0.514 m s−1) and annual root-mean-square intensity errors ranging from 10.3 to 14.1 kt. A direct comparison between the previous version and the one reported here shows root-mean-square intensity error improvements in all years with a best improvement in 2009 from 17.9 to 10.6 kt and an overall improvement from 14.8 to 12.9 kt. In addition, samples from the 7-yr period are binned based on level of intensity and on the strength of environmental vertical wind shear as extracted from Statistical Hurricane Intensity Prediction Scheme (SHIPS) data. Preliminary results suggest that the deviation angle variance technique performs best at the weakest intensity categories of tropical storm through hurricane category 3, representing 90% of the samples, and then degrades in performance for hurricane categories 4 and 5. For environmental vertical wind shear, there is far less spread in the results with the technique performing better with increasing vertical wind shear.

Archibald Menzies (1754–1842), an early botanist on the northwestern seaboard of North America, 1792–1794, with further notes on his life and work

2001 ◽  
Vol 28 (1) ◽  
pp. 71-122 ◽  
Author(s):  
ERIC W. GROVES
Keyword(s):  
North America ◽  
Pacific Coast ◽  
Later Life ◽  
Northwest Pacific ◽  
Historical Events ◽  
Short Biography

ABSTRACT: This paper includes a short biography of Menzies and an outline of the historical events on the northwest Pacific coast leading up to Vancouver's voyage. A table listing the botanical visitors to that area prior to 1792 is given followed by a résumé of the evolution of Menzies's journal. Sources used in compiling the chronology of his movements during Vancouver's voyage are then set down, ending the section with an account of Menzies's own visit, 1792–1794. His method of plant collecting is discussed along with an account of his collections and their subsequent disposal. The paper concludes with details of Menzies's later life, his connection with other botanists of the day, and an assessment of his achievements.

Sign in / Sign up

Export Citation Format

Share Document