Skin-Flying into the Storm Center

1971 ◽  
Vol 24 (3) ◽  
pp. 424
Author(s):  
Laurence Lieberman
Keyword(s):  
2019 ◽  
Vol 58 (9) ◽  
pp. 1993-2003 ◽  
Author(s):  
David Mayers ◽  
Christopher Ruf

AbstractA new method is described for determining the center location of a tropical cyclone (TC) using wind speed measurements by the NASA Cyclone Global Navigation Satellite System (CYGNSS). CYGNSS measurements made during TC overpasses are used to constrain a parametric wind speed model in which storm center location is varied. The “MTrack” storm center location is selected to minimize the residual difference between model and measurement. Results of the MTrack center fix are compared to the National Hurricane Center (NHC) Best Track, the Automated Rotational Center Hurricane Eye Retrieval (ARCHER), and aircraft reconnaissance fixes for category 1–category 3 TCs during the 2017 and 2018 hurricane seasons. MTrack produces storm center locations at intermediate times between NHC fixes with a factor of 5.6 overall reduction in sensitivity to uncertainties in the NHC fixes between which it interpolates. The MTrack uncertainty is found to be larger in the cross-track direction than the along-track direction, although this behavior and the absolute accuracy of position estimates require further investigation.


Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 942
Author(s):  
Benjamin Davis ◽  
Xuguang Wang ◽  
Xu Lu

Six-hourly three-dimensional ensemble variational (3DEnVar) (6H-3DEnVar) data assimilation (DA) assumes constant background error covariance (BEC) during a six-hour DA window and is, therefore, unable to account for temporal evolution of the BEC. This study evaluates the one-hourly 3DEnVar (1H-3DEnVar) and six-hourly 4DEnVar (6H-4DEnVar) DA methods for the analyses and forecasts of hurricanes with rapidly evolving BEC. Both methods account for evolving BEC in a hybrid EnVar DA system. In order to compare these methods, experiments are conducted by assimilating inner core Tail Doppler Radar (TDR) wind for Hurricane Edouard (2014) and by running the Hurricane Weather Research and Forecasting (HWRF) model. In most metrics, 1H-3DEnVar and 6H-4DEnVar analyses and forecasts verify better than 6H-3DEnVar. 6H-4DEnVar produces better thermodynamic analyses than 1H-3DEnVar. Radar reflectivity shows that 1H-3DEnVar produces better structure forecasts. For the first 24–48 h of the intensity forecast, 6H-4DEnVar forecast performs better than 1H-3DEnVar verified against the best track. Degraded 1H-3DEnVar forecasts are found to be associated with background storm center location error as a result of underdispersive ensemble storm center spread. Removing location error in the background improves intensity forecasts of 1H-3DEnVar.


1987 ◽  
Vol 85 (5/6) ◽  
pp. 1197
Author(s):  
Nelson P. Miller ◽  
David M. O'Brien

1992 ◽  
Vol 19 ◽  
pp. 411-433 ◽  
Author(s):  
Dan Wylie

Literary practitioners have long been, often uncomfortably, aware of the ambivalently fruitful and constraining rhetorical influences of the past. Writers successively utilize or rebel against traditional tropes, poetic conventions, and narrative norms, balancing cultural depth against individualist innovation, acceptability against rejection, public intelligibility against the opacity of private connotation. By such gestures towards the traditions, literature challenges, upholds, or leaves unquestioned the moral, political, and cultural pre-suppositions of its day.South African historiography is less aware than it might be of its textuality, in this sense, of its immersion in a similar “anxiety of influence,” as Harold Bloom has termed it. Little attention has been paid to its rhetorical lineaments and heritage or to the ways historians have read, used, and departed from one another. This is dramatically illustrated by the case of the historiography of Shaka Zulu (assassinated in 1828). Nowhere else has such poverty of evidence and research spawned such a massively unquestioned, long-lived, and monolithic “history.” Only in the last decade has the legendary, verbal construction of the Shaka figure been seriously questioned; only in 1991, at an important colloquium at the University of the Witwatersrand, was something approaching an academic consensus reached that themfecane—the notion of Shaka's Zulus as the “storm-center” of a sub-continental explosion of autophagous, black-on-black violence—was no longer a credible vehicle for understanding the early nineteenth century in southern Africa.


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