All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 78 17 4
PDF Downloads 16 10 4

The Detection of Flow Asymmetries in the Tropical Cyclone Environment

Michael J. ReederMeteorological Institute, University of Munich, Federal Republic of Germany

Search for other papers by Michael J. Reeder in
Current site
Google Scholar
PubMed
Close
,
Roger K. SmithMeteorological Institute, University of Munich, Federal Republic of Germany

Search for other papers by Roger K. Smith in
Current site
Google Scholar
PubMed
Close
, and
Stephen J. LordNational Meteorological Center, NOAA, Washington, D.C.

Search for other papers by Stephen J. Lord in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

Data from a numerical simulation of a moving barotropic vortex on a sphere with 10-km resolution are used to assess the ability of a state-of-the-art objective analysis scheme to detect certain large-scale tropical cyclone asymmetries, the so-called “beta gyres” to which the cyclone motion appears to be attributed.

A series of analyses is conducted, first using the entire dataset and then taking subsets of it. Four subsets were considered in which data at a regular array of points were extracted, progressively increasing the separation between points. A fifth calculation was considered in which data were selected at points corresponding to the proposed upgraded upper-air network for a tropical cyclone motion experiment in the northwest Pacific region.

It is shown that for a moderate-sized tropical cyclone-scale vortex, a regular grid spacing on the order of 100–150 km is required to adequately define the gyres, at least when the ambient flow is weak. The upgraded upper-air network was found to be inadequate by itself for this purpose, suggesting that aircraft dropwindsonde data are a prerequisite for this task.

Abstract

Data from a numerical simulation of a moving barotropic vortex on a sphere with 10-km resolution are used to assess the ability of a state-of-the-art objective analysis scheme to detect certain large-scale tropical cyclone asymmetries, the so-called “beta gyres” to which the cyclone motion appears to be attributed.

A series of analyses is conducted, first using the entire dataset and then taking subsets of it. Four subsets were considered in which data at a regular array of points were extracted, progressively increasing the separation between points. A fifth calculation was considered in which data were selected at points corresponding to the proposed upgraded upper-air network for a tropical cyclone motion experiment in the northwest Pacific region.

It is shown that for a moderate-sized tropical cyclone-scale vortex, a regular grid spacing on the order of 100–150 km is required to adequately define the gyres, at least when the ambient flow is weak. The upgraded upper-air network was found to be inadequate by itself for this purpose, suggesting that aircraft dropwindsonde data are a prerequisite for this task.

Save