T.N. Krishnamurti
Department of Meteorology
Florida State University
Tallahassee Florida 32306
(work) (850) 644-2210
(fax) (850) 644-9642
We propose to carry out a detailed analysis of the global(and regional) data sets over the PEM-Tropics B domain during the winter and early spring months of 1999. Furthermore we propose to undertake the background meteorological studies relevant to important field phase observations on trajectories, passive tracer transports and simple chemical transport modelling for PEM-Tropics B.
Proposed Work:
(a) Reanalysis
Global high resolution reanalysis utilizing a global spectral model and physical initialization will be carried out. This reanalysis will use a transform grid resolution (horizontal) comparable to the best available satellite rainfall product (the SSMI and TRMM) over the Pacific Ocean. We expect to include TRMM data in our reanalysis. We propose to cover a period between January 1 through March 31, 1999, for the reanalysis. We shall be performing once daily reanalysis at 16 vertical levels.
(b) Back Trajectories
The analysis model, described in the previous section, will be used to define the trajectories in a consistent manner. Thus, the velocity components (u,v,w) are used directly at the model levels and a three dimensional semi-lagrangian algorithm, krishnamurti and Bounoua (1996), is used to construct the back trajectories. Unlike other conventional methods for trajectory calculations, this method uses the model dynamics and model physics in a very consistent manner.The aforementioned analysis carried out over a six hour data assimilation window will provide the possibility for the construction of model/data related four dimensional trajectories that can provide the most detailed meso to large scale depictions of parcel motions over and across the western equatorial Pacific, the South Pacific, the ITCZ and the SPCZ. The analysis being global, these trajectories will convey important information on the parcel histories from and into other ocean basins with respect to the PEM-Tropics domain and the stratospheric incursions of ozone as well. The reanalysis levels extend to 30 millibar which is just above the ozone maximum.
(c) Passive tracer transports
Given a four dimensional description of the motion field from our reanalysis (every six hours) it is possible to performi. The details of this procedure are described in Krishnamurti et al. 1996. The dfinition of the initial state of a passive tracer (and a sustained source) for this PEM -Tropics B environment need to be defined. We shall be working on these major issues.
In order to advect the passive tracer, one makes the assumption that the rates of emission of the tracer. In the vertical, the initial distribution of tracer needs to be defined over the source regions. Horizontal and vertical motions provide the continous passive tracer transports.Winds are interpolated to every 15 minutes from the reanalysis in order to provide robust 4-dimension passive tracer transport.
(d) Chemical transport
We have developed the basic tools to explore the chemical transports of biomass burns from South America, Indonesia, Borneo and of OH, ozone and NOx. Since the transports will be driven by our reanalysis products, we expect that we can indeed make useful contributions for PEM-Tropics B. Our design of chemical transport experiments will also be closely guided by the above or below extrema of chemical measurements that would be provided by the field phase aircraft flight mission data from PEM-Tropics B.