Browsing by Author "Bhattacharya, Y."
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Item Open Access Initial MST radar observations of upper tropospheric-lower stratospheric duct-like structures over Jicamarca, Peru(European Geosciences Union, 2012-11-22) Li, Z.; Naqvi, S.; Gerrard, A. J.; Chau Chong Shing, Jorge Luis; Bhattacharya, Y.Persistent wind jet structures along zonal and meridional fields, believed to be caused by stationary gravity waves, were detected in February 1999 in mesospherestratosphere-troposphere (MST) radar wind measurements of the troposphere and lower stratosphere over Jicamarca, Peru. Over a continuous seven day span of MST-data analyzed in this study, two days of observations showed signatures of wave-like structures in the upper troposphere/lower stratosphere wind jets associated with the phases of the stationary gravity waves. We believe these wave-like structures are ducted gravity waves. We present these initial observations, their characteristics, and the results of simple numerical simulations used in an attempt to mimic these observed features. Although a fair replication of the observed ducted structure in the numerical model is found, the observed period of ∼90 min is nonetheless much longer than what is traditionally observed. As a result, the specific physical nature of the observed structures is not fully established. Nevertheless, given the high quality of the observations, we demonstrate here that continued analysis of this data set and concurrent modeling efforts will allow for a better understanding of Doppler ducts at high spatial and temporal resolution, and the results presented here can ultimately be applied to studies of middle atmospheric fronts, ducts, and bores.Item Open Access Numerical modeling of lower stratospheric Doppler ducted gravity waves over Jicamarca, Peru(European Geosciences Union (EGU), 2011-07) Li, Z.; Naqvi, S.; Gerrard, A. J.; Chau Chong Shing, Jorge Luis; Bhattacharya, Y.Persistent jet structures along zonal and meridional fields, believed to be caused by stationary gravity waves, were detected in February 1999 in MST wind measurements of the troposphere and lower stratosphere over Jicamarca, Peru. Over a seven day span, two days of observations showed signatures of a Doppler ducted gravity wave in the upper troposphere/lower stratosphere. Herein we present the observations, their characteristics, and results of numerical simulations used to mimic these observed features. Though a fair replication of the observed ducted structure in the numerical model is found, the observed period of ~90 min is nonetheless longer than anticipated and raises concern as to the specific physical nature of the observed structures. However, given the high quality of the observations, we demonstrate that continued analysis of this data set and concurrent modeling will allow for a better understanding of Doppler ducts at high spatial and temporal resolution which can ultimately be applied to studies of mesospheric ducts and bores.