Summary

Description

The "HIRDLS/Aura Level 3 Dinitrogen Pentoxide (N2O5) Zonal Fourier Coefficients" version 7 data product (H3ZFCN2O) contains the entire mission (~3 years) of HIRDLS data expressed as zonal Fourier coefficients in 1 degree latitude bands and 121 pressure levels. The coefficients are computed from the HIRDLS Level 2 profiles with a Kalman filter approach using both forward and backward passes in time. Expressed as the mean and up to 7 sine and cosine coefficients (4 waves for ascending and descending, 7 waves for combined), these coefficients may be used to compute values at any longitude. The data are provided on a pressure grid with 24 levels per decade, corresponding to about 1 km vertical resolution. The vertical range of the data is 82.5 to 1.0 hPa. The precision values are given by the root-mean square of the differences between the estimated fields and the input data. The data are stored in the version 5 Hierarchical Data Format for the Earth Observing System (HDF-EOS5), which is an extension of the HDF5 format. Each file contains a zonal object with data for the entire mission with separate data fields for ascending (daytime), descending (nighttime), and combined orbit node. The data arrays have 145 latitude steps (-64 to 80 degrees), 121 pressure steps, 15 Fourier coefficients (mean plus first 7 cosine and 7 sign waves), and 1151 daily time steps from January 22, 2005 through March 17, 2008. The coefficients are computed at a daily synoptic time of 12:00 UTC. That time is expressed in TAI-93 seconds (seconds since January 1, 1993) and the date is also stored in separate year, month and day fields. The ascending and descending datasets include LocalSolarTime and SolarZenithAngle values. Parameters contained in the data files include the following: Variable Name|Description|Units N2O5|Dinitrogen Pentoxide (N2O5) Volume Mixing Ratio|mol/mol End of parameter information