Wind Retrieval at Millimeter and Submillimeter Wavelengths Mike Janssen 26 June, 2001

Wind velocity vertical resolution @ 50 km Submillimeter Lines The spectral line due to 13CO as seen along a single line of sight (i.e., pencil beam) tangent to 50-km altitude The altitude weighting function for a frequency offset 1.5 MHz from the line center in the previous plot. This is approximately the point of steepest brightness gradient with frequency and is the point with the most sensitivity to a wind-caused Doppler shift.

Wind velocity vertical resolution @ 100 km Submillimeter Lines

Difference between 50-km 13CO line at rest and Doppler-shifted by a 10-meter wind in the line of sight. Submillimeter 13CO Line Note: DT/MHz ~ 1.5 K For Dt - 10 s Ts = 2500 K Note that the 10-sec measurement uncertainty of a 2500 K dsb noise temperature receiver in a 1-MHz bandwidth is ~ 1.5 K, so we can expect this velocity to be readily measureable.

10-sec integration/point Wind Retrieval, Submillimeter CO Trec = 2500K 10-sec integration/point 12CO Altitude, km 13CO Retrieval Error, m/s

10-sec integration/point Wind Retrieval, Millimeter CO Trec = 1000K 10-sec integration/point 12CO Altitude, km 13CO Retrieval Error, m/s