Map Magnetic Anomalies


  "Plot" button,    Color code by DB field, and pick the desired numeric field.
TF_UNCOMP: Total Field, uncompensated.  The values range from 49224 to 49470 nT, and generally increase with latitude.  This is a mid latitude location; the earth's field varies from about 25,000 to 75,000 nT.
TF_COMP: Total Field, compensated. Values range from 4216 to 4470, and reveal some finer detail compared to the uncompensated.
ANOM_S: Short wavelength anomalies.  Values range from -95 to +164.  This correction subtracts a trend surface, a generalized surface, from the readings.  This highlights local changes, which could be due to objects on the seafloor.  The longer wavelength patterns reflect regional changes in the character of the rocks.

There are only a few points with very large anomalies (colored in blue for the negative anomalies, with the value lower than expected, and red and purple for the positive with a higher value than expected.  Much of the color scale remains unused, with the green and cyan dominating.

ANOM_S: Short wavelength anomalies, with the colors stretched.   The most extreme anomalies no longer stand out, but more anomalies are present.

  •  Stats, Historgram to see the distribution of values, and change the values for the color on the display so that there are a significant number of values shown with both the low (blue) and high (red) parts of the color scale.
  •   Pick color palette and change the values for the color extremes.

last revision 2/16/2015