CEDAR Workshop, Boulder CO June 20-25, 2010 Statistical Analysis of COSMIC Derived Abel Profiles Jet...

CEDAR Workshop, Boulder CO June 20-25, 2010

Statistical Analysis of COSMIC Derived Abel

Profiles

Jet Propulsion LaboratoryCalifornia Institute of Technology

M/S 238-6004800 Oak Grove DrivePasadena CA 91109

Philip Stephens, Attila Komjathy, Brian Wilson, Xiaoqing Pi and Anthony J. Mannucci


Outline

• Introduction• Motivation for this study

• Analysis Framework• Results• Summary


Abel Inversion

• With F(y) the integrate line-of-site TEC and f(r) the altitude dependent density the Abel inversion is defined as

• Major assumption: For occultation measurements we have no horizontal gradients

– This is obviously false in reality– What is the impact of this assumption for real data?

• The Abel is extremely useful, however, as it provides some estimate of 3d structure from the data alone


Motivation for Study

• An effort was made to try use Abel profiles to develop a climatology

• Found important structure was ‘smeared’ no matter what averaging methods were used

• Hypothesis was the spherical symmetry of Abel inversion assumption would be broken in many cases

• Can we define some filter which can effectively provide a subset of potentially bad Abel inversions, with the members not in the subset all good inversions?


Analysis Framework

• Built database of Abel Profiles for 05/01/2010• Derived from 1 second TEC data, ~1400 profiles• Ap: 3.0, Kp: 1- very little solar activity

• Linked to database profiles generated by assimilation of COSMIC data into JPL/USC GAIM

• Used 30 second data for these results• Linked to database VTEC generated by GIM 3-shell model

• Ground data only• Slice profiles according to three criteria

• Low/Med/High Magnetic Latitude (±20, ±50, >50)• Dawn/Midday/Dusk/Midnight (3-9 LT, 9-15 LT, 15-21 LT, 21-24/0-3 LT)• Length of arc, measured by

with short/medium/long (±5, ±30,>30)• Computed Pearson Coefficient (r) and slope of line of best fit (m)• Hypothesis: Abel will break down most often when spherical

symmetry breaks down – large gradients and long spatial tracks


Filtering Arcs by Magnetic Latitude

Low lat (<20 degrees)

Mid lat (20<x<50 degrees)

High lat (>50 degrees)


Nmf2 and Hmf2 Correlation Plots


VTEC at High Latitude, Pearson Coefficient


Correlation Plots High Latitude

Long-arc, high lat, dusk

Long-arc, high lat, midday

Medium-arc, high lat, midnight

2

2

1

1

3

3


High Lat Correlations, Nmf2, Hmf2


Case 1: Long arc, High Lat, Dusk


Case 2: Long arc, High Latitude, Midday


Case 3: High lat, medium arc, midnight


Mid Latitude VTEC, Pearson Coefficient


Mid Latitude Correlation Plots

Mid latitude, midnight long arcs, only 5 points though

44

4

4


Case 4: Mid Lat, Long Arc, Midnight


Low Latitude VTEC, Pearson Coefficient


Correlation Plots Low Latitude

Long-arc, low lat, dusk

Long-arc, low lat, midday

6 6

55


Low Lat Correlation Plots, Hmf2, Nmf2


Case 5: Long arc, Low lat, Dawn


Case 6: Long arc, Low lat, Midday


Conclusions

• It does appear there is significantly more variability in comparing Abel profiles versus GAIM profiles in cases where spherical symmetry approximation is likely to breakdown

• This study was a test case of a very calm day• Expect more variability for more active days

• Still to do:• Extend study to multiple days with different conditions• Develop a measure of ‘physicality’ of profiles and apply to Abel

and GAIM profiles under different filters– Possibly using fits to Vary-Chapman function

• Measure effectiveness of suggested filters– E.g. what percentage of ‘bad’ profiles are captured by filters

• Important note: vast majority of profiles appear to correlate well to GIM VTEC and GAIM 3d structure


Backup slides


High Lat NmF2, Pearson Coefficient


Mid Lat, Nmf2, Pearson Coefficient


Low Lat Nmf2, Pearson Coefficient


Hmf2 High Lat, Pearson Coefficient


Hmf2 Mid latitude, Pearson Coefficient


Hmf2 low lat, Pearson Coefficient

CEDAR Workshop, Boulder CO June 20-25, 2010 Statistical Analysis of COSMIC Derived Abel Profiles Jet...

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