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Getting and Using SSUSI Data from the SSUSI Website, and Website Features

Robert Schaefer and Giuseppe Romeo for the SSUSI team

Robert Schaefer Giuseppe RomeoRobert.Schaefer@jhuapl.edu Giuseppe.Romeo@jhuapl.edu240-228-2740 240-228-5905

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Overview

How to do analysis with SSUSI data SSUSI Web and features

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How to Analyze SSUSI data

So you have an idea to investigate some upper atmospheric phenomenon – what do you do now?

First, Identify time period of the data you want. Second, identify the appropriate data product(s) you need. Third, Retrieve the data Fourth, identify Variables that have the information you want Fifth, identify any quality issues Sixth, Read and access the data

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1. Identify the Time Period

If you have a pre-defined time period, see discussion of data availability page coming up later to determine what data exist for the period

If not, the SSUSI Website can help L1B Daily Summaries – found in the SSUSI Gallery http://ssusi.jhuapl.edu/images_daily_l1b 3 color images to represent 3 UV color images

Red = LBH Short Green = 1356 Å Blue = 1304 Å

Variety of perspectives

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SSUSI L1B daily Summary Gallery Time frame,

satellite, date

Slideshow Perspective GUVI web

site will soon look like this, too.

Can see many features of interest

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Features in Summary image Brightness of

color corresponds to UV color intensity

Equatorial Ionosphere

White means all three colors are bright.

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Other perspectives available in Summary Stacked Limb Plots Stacked Disk Plots Polar view plots Orthographic perspectives Can go browsing for features

Stacked Limb Plot

Polar Perspective Plot

EquatorialionosphereDayglow AuroraAurora

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If you need want higher time resolution browse Google Earth galleries

Require Google Earth plugin (freely downloadable from Google)

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2. Identify Data Products You need

Electron Density Low Latitude Electron Density Profiles

– Nightside• 3D density cube: EDR-IONO• Bubbles and Characteristics: EDR-IONO• Mutual neutralization corrected profile: EDR-NIGHT-LIMB

– Dayside• Topside density (only above 400 km): EDR-DAY-LIMB• Disk F-region NmF2, HmF2 is an unvalidated product – use at your

own risk: EDR-DAY-DISK High Latitude Electron Density Profiles

– E-Region densities: EDR-AURORAL Dayside Neutral Densities:

O/N2: EDR-DAY-DISK Solar Extreme UV Flux

Qeuv: EDR-DAY-DISK

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Identify Products (for the polar region analysis)

Auroral Zone products - All are in the: EDR-AURORAL Precipitating electron energy flux (Q) and mean energy (E0)

(conductances!) Hemispheric Power Regions of proton precipitation Auroral boundaries (poleward, equatorward),(global/pixelated) Discrete arc locations Magnetic field lines from the auroral boundary

Auroral Oval predition –EDR-AURORA-PRED New product (not validated) gives predicted auroral energy flux,

mean energy and boundary

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3 Retrieve the Data

Single files are clickable

Case where you want more than one file will be discussed later

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DMSP program is winding down – one more SSUSI to launch (2016?)

Long term data support> NASA: Space Physics Data Facility – http://spdf.gsfc.nasa.gov CDAweb http://cdaweb.gsfc.nasa.gov/istp_public/

Virtual ITM Observatory – http://vitmo.jhuapl.edu

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Data Availability – for the future

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4. Identify Variables Needed

Separate Document discusses this - Here we give an overview Coordinates

Low latitude Disk – Piercepoint Latitude, Longitude at – Night Altitude 350 km – Day Altitude: 150 km– Auroral Altitude: 110 km

Low Latitude Limb – Tangentpoint Latitude, Longitude, and Altitude Auroral Zone – Geographic and Magnetic Coordinates available

– Magnetic Latitude and Magnetic Local Time Time

Year, DOY, and Seconds of the day – Note seconds of the day called “TIME” in all files except AURORAL files

where it is called UT (actually UT_N for northern hemisphere magnetic coordinates and UT_S for southern hemisphere coordinates)

Other variables more specific to the product and type of analysis

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Example DQI

EDR-NIGHT-LIMB DATA_QUALITY variable is an array – 1 per pixelBit # Meaning if set to true (1)0 VER fit unsuccessful (chi squared test: rchi2v>10)1 Chapman fit unsuccessful (chi squared test: rchi2c>10)2 NmF2 uncertainty > 50% 3 HmF2 < 0 km4 HmF2 > 500 km5 HmF2 uncertainty > 50% 6 NRP < 77 SZA < 105 degrees8 MeV contamination9-15 Spare

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5. Data Quality Issues

Data Quality Indices – Integers used as bit fields Individual bits have meaning for different failure conditions Designed so that 0=good, 1=bad Simplest thing to do:

– Evaluate as integers – Throw away anything that is not 0

Other Data indicators Aurora – sometimes files only cover one hemisphere SOUTH_DATA, NORTH_DATA are set to 1 if Data exists for the

SOUTH, NORTH hemispheres, 0 if no data. Variables can be checked to see if any useful data exists

Also Pixels with no data are set to IEEE NaN value to prevent accidental use in averages

no problem for IDL programmers Good_data_indices= where(finite(variable_arrary))

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6. Read and Access Data

IDL Software tools available (http://ssusi.jhuapl.edu/software_tools)

These allow you to read and plot data Libraries in many computer language for reading NetCDF

available from Unidata UCAR web site (http://www.unidata.ucar.edu/software/netcdf/index.html)

Most useful utility we have found: read_ncdf.pro Reads in everything in the file and populates an idl structure with a

single call Variable names become tags in the structure Reads in all global header information, including geophysical

indices supplied by the Air Force in realtime Plotting routines show examples of reading and manipulating

most useful variables

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SSUSI and GUVI Websites

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SSUSI Website Most of the content is available to the general public, some is

restricted to registered users New interface/New tools

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New Features for SSUSI website

Data Availability Data Retriever Image Galleries (including Google Earth KMZ file) Enhanced Data Retriever (registered users ONLY) Software tools

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SSUSI Data Availability(http://ssusi.jhuapl.edu/data_availability)

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Data Retriever (http://ssusi.jhuapl.edu/data_retriver)

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Data Products (http://ssusi.jhuapl.edu/data_products)

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Daily Data Retriever (http://ssusi.jhuapl.edu/daily_data_retriever)

To prevent abuse by robots, only registered users can retrieve data for periods longer than 1 orbit.

For Longer Periods than a day, need to request them by e-mail to one of us on the SSUSI team

Compressed files covering a range of dates can be downloaded by registered users.

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User Requested Data Archive(http://ssusi.jhuapl.edu/data_archive)

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Daily Summary Images(http://ssusi.jhuapl.edu/images_daily_l1b)

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EDR-AURORAL KMZ gallery(http://ssusi.jhuapl.edu/gal_edr-aur)

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EDR-IONOSPEHERE (http://ssusi.jhuapl.edu/gal_edr-iono)

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GUVI New Data Products

Thermospheric O/N2 Gallery Level 1B Spectrograph Gallery Thermospheric O/N2 Gallery and Total Electron Control SSUSI-Like EDR-AURORAL, EDR-IONOSPHERE, SDR

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GUVI Thermospheric O/N2 Gallery(http://guvi.jhuapl.edu/site/gallery/guvi-galleryl3on2.shtml)

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GUVI Level 1B Spectrograph Gallery(http://guvi.jhuapl.edu/site/gallery/guvi-galleryl1bspec.shtml)

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GUVI Thermospheric O/N2 Gallery and TEC(http://guvi.jhuapl.edu/site/gallery/guvi-galleryl3on2tec.shtml)

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SSUSI Like EDR-AURORAL(http://guvi.jhuapl.edu/site/gallery/NewProduct/edr-aur/guvi-gallery.shtml)

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SSUSI Like EDR-IONOSPHERE(http://guvi.jhuapl.edu/site/gallery/NewProduct/edr-iono/guvi-gallery.shtml)

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SSUSI Like SDR(http://guvi.jhuapl.edu/site/gallery/NewProduct/sdr/guvi-gallery.shtml)

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What’s to come, funding permitting!

New web interface for GUVI NetCDF 4 (compressed and browseable format) Simpler Filenaming scheme Solar Storm alert based on Auroral SSUSI data