NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: The taxonomy of refraction
From: Marcel Tschudin
Date: 2011 Mar 31, 15:58 +0300
From: Marcel Tschudin
Date: 2011 Mar 31, 15:58 +0300
In January an abnormal refraction phenomenon near the horizon has been discussed here under the above subject. In this context I provided some links to atmospheric data which may help to understand the conditions which led to the phenomenon. One such source related to the Sea Surface Temperature (SST) where I wrote: "The best I could find so far for your area is here http://www7320.nrlssc.navy.mil/global_nlom32/ ...".
I previously had access to data with higher resolutions than those provided under the mentioned navy-mil-link but which - for some reason - were not any more available at that time. It looks to me like a concentration process has been going on for providing world-wide data of the seas. I recently have been advised to use now the following Web-based-tools for accessing (analysed) data:
- For "recent" historical data: http://ourocean.jpl.nasa.gov/ and
- for "older" historical data: http://data.ncof.co.uk:8080/ncWMS/godiva2.html
The JPL-data have a higher resolution than NCOF-data but the JPL-data are at the moment only available for the last two or three years. The data sets are updated on a daily base.
These sources may eventually be useful when investigating some abnormal refraction phenomenon. However, in the case of John's photo of the light house it unfortunately can not explain the reason for the inferior mirage. The sea was about as warm as John mentioned and the air had about the same temperature or was even slightly warmer. I attach here a screenshot of the JPL-data for August10, 2010 showing the SSTs in the area where John took the photos from the light house.
Marcel
I previously had access to data with higher resolutions than those provided under the mentioned navy-mil-link but which - for some reason - were not any more available at that time. It looks to me like a concentration process has been going on for providing world-wide data of the seas. I recently have been advised to use now the following Web-based-tools for accessing (analysed) data:
- For "recent" historical data: http://ourocean.jpl.nasa.gov/ and
- for "older" historical data: http://data.ncof.co.uk:8080/ncWMS/godiva2.html
The JPL-data have a higher resolution than NCOF-data but the JPL-data are at the moment only available for the last two or three years. The data sets are updated on a daily base.
These sources may eventually be useful when investigating some abnormal refraction phenomenon. However, in the case of John's photo of the light house it unfortunately can not explain the reason for the inferior mirage. The sea was about as warm as John mentioned and the air had about the same temperature or was even slightly warmer. I attach here a screenshot of the JPL-data for August10, 2010 showing the SSTs in the area where John took the photos from the light house.
Marcel
File:
