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 |