| Start Date | Start Time | End Date | End Time | Data Quality Metric |
|---|---|---|---|---|
| 07/17/1994 | 0000 | 04/06/1995 | 2359 | Suspect |
| Subject: | GOES data in Mercator projection |
| DataStreams: | sgpgoes7radX1.a1, sgpgoes7ir8X1.a1, sgpgoes7visX1.a1, sgpgoes7irX1.a1, sgpgoes7rad8X1.a1 |
| Description: | DQR No: Platform: sgpgoes7X1. etc
Subject: GOES data in Mercator projection
Date Submitted: 18 April 1995
Submitted By: Peter Minnett ___ Instrument Mentor
_X_ EST Member
___ Science Team Member
___ Other _____________________________
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at problems@arm.gov.
Platform/Measurement:
What level data: (raw,a0,a1,b1,c1 etc): a1
What location was the data collected at: SeaSpace
Period of time in question
Begin Date 07/17/94 Time : (GMT)
End Date 04/06/95 Time : (GMT)
Data should be labeled:
___ questionable _X_ All data fields affected
___ incorrect ___ Only some data fields affected
___ wrong calibration
___ others
Discussion of Problem:
The edges of the remapped GOES-7 images that have been cast into a Mercator
projection do not lie along constant latitude (top and bottom) or constant
longitude (left and right). Here are some values, all derived from the same
input image:
a) for an infrared image derived from 4km data, with 4km output pixels:
top left is at: 47.2555N, 105.271W
top right is at: 47.2596N, 90.051W
bottom left is at: 24.3205N, 105.307W
bottom right is at: 24.3403N, 89.656W
b) for an infrared image derived from 4km data, with 4km output pixels:
top left is at: 47.1464N, 105.287W
top right is at: 47.2748N, 89.627W
bottom left is at: 24.3205N, 105.307W
bottom right is at: 24.3403N, 89.656W
c) for a visible image derived from 1km data, with 1km output pixels:
top left is at: 39.4176N, 99.4369W
top right is at: 39.4167N, 95.5312W
bottom left is at: 33.6858N, 99.4332W
bottom right is at: 33.6861N, 95.5313W
Examples a and b are supposed to overlay each other, and while the bottom right
positions are the same, the other corners have different coordinates. The
discrepances are sub-pixel.
Other observations/measurements impacted by this problem:
Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)
This is mainly `for the record'. It is a computational problem at a level
unlikely to impinge greatly on ARM data users. However, these discrepances
should not exist.
I have notified SeaSpace Support, but do not expect any immediate corrective
action.
Data Processing Notes Date |
| Suggestions: | |
| Measurements: | sgpgoes7rad8X1.a1: more
sgpgoes7radX1.a1: more sgpgoes7irX1.a1: more sgpgoes7ir8X1.a1: more sgpgoes7visX1.a1: more |