Microwave solar noise and sunspot.

Covington's measurements of solar noise intensity in the 2800 megacycles band are compared over a period of 20 months with the relative sunspot number, the total sunspot area ~A, and with a daily index ~A -H0, where A is the spot area and H0 the intensity of the magnetic field. The last comparison yields the best correlation, with a correlation coefficient of 0.9. The remaining discrepancies seem associated with rapid changes in the topography of certain spots. It is shown that these results are consistent with the expected gyromagnetic emissions associated with the magnetic field of the spots, assuming a kinetic temperature of several million degrees in the corona. Comparisons of the observed emission with the true areas and the projected areas of the spots allows an estimate of the shape of the emitting surface associated with the spots. Some indications are given of possible relations between cosmic rays and radio emissions coming from the sun and the galaxy. Paris, France, and U. S. Bureau of Standards, Washington, D. C.