Checking the ground based data

Introduction

AE, AL and AU indices are calculated using the THEMIS GMAG stations and are being put in the L1 files. However, the GMAG data often has spikes and data gaps, and other bad looking data, which corrupt the indices. To avoid this, a file has been created that records which GMAG sites are 'bad' for any particular day. It is the job of the tohban to keep this file up to date.

The tohban therefore

• checks the GMAG data for each day,
• decides which sites are 'bad' and
• puts this information in the file where the process that creates the AE index then picks it up.

How to check the data:

To check the data, use the routine thm_mult_gmag_plot.pro, which is currently part of the bleeding-edge software distribution.

IDL> thm_mult_gmag_plot,'2009-09-06'

IDL> thm_mult_gmag_plot,'2009-09-06', n_per_page = 5

(will plot 5 stations at a times).

How to edit the file:

Once you have decided which stations are bad, you edit the file. The file format is simple, just the date, and a list of sites, separated by spaces: e.g.

2009-10-13	kian rbay mcgr whit snkq tpas drby
2009-10-14	rbay mcgr whit kuuj snkq kapu drby
2009-10-15	gjoa rbay mcgr drby
2009-10-16	cdrt whit

To edit the file, follow these steps:

• log on here at SSL
• cd /disks/socware/AE_sites
• vi thm_l1gen_idx_sites_exclude.txt (Or emacs, or whatever editor you use)
• Edit the file and save,

and you're done! Ideally this should be done before 8pm PST, which is when the AE index files are created.

Final tip:

• Do it in the morning, it takes about 5 minutes.