The Student Nitric Oxide Explorer (SNOE) Database

K D Mankoff, C A Barth, S M Bailey*
Laboratory for Atmospheric and Space Physics , University of Colorado
*Center for Atmospheric Sciences, Hampton University

Introduction

This is an online version of a poster presentation at the Fall 2001 AGU Meeting. The poster number was SA22A-0705, and has the title and authors shown above. The four main sections of the poster are each presented in a section below. Use the following links to view these sections:
  1. Abstract
  2. SXP Dataset Information
  3. UVS NO Level Three Data
  4. UVS NO Level Four Data

A mini poster in Postscript format is available.. This file is 14 Mb, and will print onto a regular 8.5 x 11 page at high quality. Here is a low quality preview in JPEG format.

Abstract

The SNOE database consists of measurements of nitric oxide density in the thermosphere made with an ultraviolet spectrometer and observations of the solar soft x-ray irradiance in the 2-7 nm wavelength range obtained with an x-ray photometer for the period March 11, 1998 - September 30, 2000. The nitric oxide density data covers the altitude range 97-150 km at 3.3 km intervals, the latitude range 80 degrees S to 80 degrees N at 5 degree intervals, and the longitude range 180 degrees W to 180 degrees E at 24 degree intervals. The SNOE spacecraft is in a sun-synchronous orbit with a 10:30 AM northbound equatorial crossing, with 15 orbits per day. The basic nitric oxide data set consists of three levels of processing: (1) daily averages of nitric oxide density as a function of latitude and altitude, (2) orbit by orbit measurements of nitric oxide density as a function of latitude, altitude, and orbit number, and (3) daily maps of nitric oxide density as a function of latitude, longitude, and altitude. There is a secondary data set of two additional levels of processing: (4) column densities of nitric oxide as a function of latitude, altitude, and orbit number, and (5) ultraviolet radiance at 237 nm as a function of latitude and longitude of the spacecraft and the look direction of the spinning spacecraft. The altitude scale for four levels of processing was determined by matching the ultraviolet radiance profiles to a model of the atmospheric Rayleigh scattering. The solar soft x-ray data set consists of daily averages of the solar irradiance in the 2-7 nm wavelength range.

SXP Dataset Information

The Solar X-ray Photometer on the SNOE spacecraft has the primary objective of determining the solar soft x-ray irradiance energy into the upper atmosphere for studies of how that energy input controls nitric oxide abundances. The SXP has made daily measurements of the solar soft x-ray irradiance between 2 and 7 nm since March 11, 1998. The available data product is 935 days of SNOE SXP measurements of the integrated 2 to 7 nanometer irradiance.

The layout of the SNOE SXP data set is as follows: For each day (row) of the dataset, eight products (columns) are calculated. Two of these are SNOE data products. A sample of the ASCII data file is shown below. Under the table is a plot of column 3 of the datafile. 

TIME     TIME        SNOE 2-7nm   SNOE 2-7nm   F10.7    F10.7    Lyman          Ap
YYYYDDD  Year.Frac   Measured     1 A.U.                ave      Alpha
                     mW/m^2       mW/m^2                         p/sec/cm^2

1998070  1998.190    0.447        0.453         99.4    103.7    3.89E+11       28
1998071  1998.193    0.471        0.477        100.3    103.7    3.89E+11       14
1998072  1998.196    0.455        0.460        103.7    103.8    3.88E+11       12
1998073  1998.198    0.494        0.500        118.2    103.8    3.94E+11       10
1998074  1998.201    0.543        0.549        131.6    103.9    3.98E+11       20
1998075  1998.204    0.591        0.597        122.6    103.9    3.99E+11       12
1998076  1998.207    0.591        0.597        124.3    104.0    3.95E+11        8
1998077  1998.209    0.623        0.629        125.9    104.1    4.01E+11        4
1998078  1998.212    0.633        0.638        123.5    104.3    4.05E+11        4
1998079  1998.215    0.682        0.688        125.5    104.6    4.07E+11        8
Column 1: Time, in YYYYDDD format
Column 2: Time, in Year.Fraction_of_year format
Column 3: SNOE SXP 2 - 7 nm solar irradiance (mW / m^2)>
Column 4: SNOE SXP 2 - 7 nm data, adjusted to 1 A.U.
Column 5: F10.7 daily data (Ottawa/Penticton radio flux)
Column 6: F10.7 81-day average data (Ottawa Penticton radio flux)
Column 7: UARS SOLSTICE Lyman Alpha (photons / sec / cm^2)
Column 8: Fredericksburg Ap geomagnetic activity index

UVS NO Level Three Data

SNOE UVS Level Three (L3) data are orbit by orbit measurements of nitric oxide density as a function of altitude, latitude, orbit, and time.


There are fifteen orbits per day. Each orbit contains data location parameters that allow the data to be imaged in any combination of the following dimensions: Altitude, latitude, longitude, and time.

Below, fifteen consecutive orbits have been selected. The data at 106 km for all latitudes has been extracted and rotated counterclockwise. Each orbit is then placed on a projection of Earth at the longitude sampled.

     


UVS NO Level Four Data

SNOE UVS Level Four (L4) data are daily averages of nitric oxide density as a function of altitude, latitude, and time. Each day of the file is made by averaging fifteen consecutive orbits of Level Three data.




The nitric oxide peak occurs at 106 km, with slight seasonal and hemispheric variation. A plane taken out of the dataset at 106 km is imaged below. This time vs latitude image covers the first 935 days of the SNOE mission, from March 11, 1998 (day of year: 079) through September 30, 2000 (day of year: 274). Vertical black lines are data outages due to spacecraft sampling errors and data downlink loss. The UVS does not measure NO during the polar winter night.