Engineering topics

Winslow, N.

Publications and source records attributed to Winslow, N..

3 records

NASA NTRS2003

Monitoring and Assimilation of MIPAS and SCIAMACHY Ozone Data

Preliminary results are presented from experiments that integrate ozone observations from two ENVISAT-borne instruments with the ozone data assimilation system developed at NASA's Data Assimilation Office (DAO). The data used are ozone total column provided by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and stratospheric profiles from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument. The DAO's existing system sequentially assimilates the Solar Backscatter Ultraviolet/2 total and partial ozone column data. Incorporation of SCIAMACHY and MIPAS data is done in two stages. First, the observations are monitored. The monitoring consists of computing the differences between Envisat observations and the ozone system forecast, i.e. observed-minus-forecast (O-F) residuals. The O-F residuals are then analyzed using simple statistical methods to examine the spatial distribution of differences, which are large for SCIAMACHY near the terminator. In the second stage, the MIPAS data will be actively assimilated along with the SBW/2 observations; any preliminary results of note will be discussed.

Wargan, K.↗

NASA NTRS2003

Assimilation of Satellite Ozone Observations

This talk will discuss assimilation of ozone data from satellite-borne instruments. Satellite observations of ozone total columns and profiles have been measured by a series of Total Ozone Mapping Spectrometer (TOMS), Solar Backscatter Ultraviolet (SBUV) instruments, and more recently by the Global Ozone Monitoring Experiment. Additional profile data are provided by instruments on NASA's Upper Atmosphere Research Satellite and by occultation instruments on other platforms. Instruments on Envisat' and future EOS Aura satellite will supply even more comprehensive data about the ozone distribution. Satellite data contain a wealth of information, but they do not provide synoptic global maps of ozone fields. These maps can be obtained through assimilation of satellite data into global chemistry and transport models. In the ozone system at NASA's Data Assimilation Office (DAO) any combination of TOMS, SBUV, and Microwave Limb sounder (MLS) data can be assimilated. We found that the addition of MLS to SBUV and TOMS data in the system helps to constrain the ozone distribution, especially in the polar night region and in the tropics. The assimilated ozone distribution in the troposphere and lower stratosphere is sensitive also to finer changes in the SBUV and TOMS data selection and to changes in error covariance models. All results are established by comparisons of assimilated ozone with independent profiles from ozone sondes and occultation instruments.

Stajner, I.↗

NASA NTRS2001

Constituent Data Assimilation: Challenges and Limitations

The assimilation of observations of atmospheric constituents naturally divides into two major pieces. The first is the assimilation of trace gases whose variability is related to atmospheric motions. The second is the assimilation of trace gases which are sharply influenced by chemical exchange between different constituents. In order to advance beyond the initial successes of explorative investigation of assimilation techniques, tremendous challenges must be met to improve the geophysical integrity of assimilated data products. A subject of special interest is ozone near the tropopause. At the tropopause the information from both the observations and the model simulation becomes most uncertain. However a number of important geophysical parameters, e.g. stratosphere-troposphere exchange and tropospheric ozone, require the assimilation to have high accuracy at the tropopause. This talk will review the current status of the quality of assimilated data products near the tropopause, what must be done to improve the assimilation near the tropopause, and the intrinsic limitations that will require additional sources of information in order for the field to advance.

Rood, Richard B.↗