Office Note Series on Global Modeling and Data Assimilation

The Data Assimilation Office (DAO) at Goddard Space Flight Center is currently producing a multiyear gridded global atmospheric dataset using a fixed assimilation system designed to remove the variability due to algorithm changes. While the signal due to system changes has been eliminated, changes in the input data are another potential source of spurious climate signals. In this study, a set of sensitivity experiments are performed with the Goddard Earth Observing System Version 1 (GEOS-1) assimilation system to assess the impact of including temperature and moisture information from stations on the NCEP's (National Centers for Environmental Prediction) reject list. The results from the sensitivity experiments for the northern summer of 1994 indicate that the impact of including the reject list reports is significant in the tropics. The most significant difference is found in the precipitation over the Indian summer monsoon region and the western Pacific. The precipitation without the..

Ion beam spectroscopy as a means of in-situ monitoring of thin film deposition

Low energy (5--15 keV) pulsed beam Ion Scattering Spectroscopy (ISS) and Direct Recoil Spectroscopy (DRS) are surface analytical tools which possess the ability to provide a remarkably wide range of information directly relevant to the growth of multi-component semiconductor, metal and metal oxide thin films and layered structures. Ion beam methods have not been widely used for this purpose because the design of existing commercial instrumentation is unsuitable in terms of vacuum requirements, data acquisition rate, geometric interference with the deposition equipment, and the magnitude of the ion beam dose and consequent film damage required for the acquisition of spectra with reasonable signal-noise ratios. Users of advanced custom-built Time-of-Flight (TOF) instruments have been largely interested in other problems and for the most part, unaware of some of the unique operational characteristics of TOF DR/ISS as they pertain to thin film growth. We discuss here some of the physical properties which may be measured by DR/ISS and describe a physical implementation of the technique which is suitable as a real-time probe of thin film deposition in terms of very low required beam dose, rapid data acquisition, physical non-interference with the deposition equipment and high ambient pressure operation

Parallel Computing at the NASA Data Assimilation Office (DAO)

This presentation discusses the NASA data assimilation project at the Data Assimilation Office at the NASA/Goddard Space Flight Center. The goal is to produce accurate gridded datasets of atmospheric fields by assimilating a range of observations along with physically consistent model forecasts. This work produces datasets that are used by the climate research community. The data come from conventional sources that are used for weather forecasts (e.g., radiosondes, earth-surface measurements, and satellite temperature retrievals), as well as new sources such as satellites that will be launched under the Mission To Planet Earth Enterprise. An end-to-end Goddard Earth Observing System (GEOS) Data Assimilation System (DAS) currently supports stratospheric flight missions and reanalysis projects for NASA. The current Core of this system (Model, and Analysis) is a multitasking algorithm that runs on Cray J90 and C90 computers at Goddard and NASA Ames Research Center. Future Core computing w..