Doppler shift, wind velocity measurements

While dust continuum emission can be used to estimate disk masses, line emission from optically thin molecules (e.g., CO) can be used to map the line-of-sight velocities in disks, using the Doppler shift of the moving gas. Evidence for Keplerian velocity profiles is typically found (e.g., Launhardt and Sargent, 2001), as is to be expected for gas in a stable orbit around a central protostar. These measurements only apply to the gas at considerable distances from the young star, however, typically at several hundred astronomical units or more. The situation inside these disks at planetary distances is not constrained by these observations, and even the outer disk measurements are subject to possible confusion with infalling gas in the envelopes and outflowing gas from stellar winds. 

One of the most important atmospheric dynamical quantities is the zonal wind (wind speed in the longitudinal direction). Wind velocities are conventionally positive for eastward winds (also called westerlies) and negative for westward winds (easterlies). They are mostly derived from the observed thermal structure of the atmosphere, although local values can be provided by radiosonde and radar measurements. To date, very few attempts have been made to directly measure the atmospheric wind components from space. The High Resolution Doppler Imager (HRDI) on board the Upper Atmosphere Research Satellite (UARS) has provided information on horizontal winds in the mesosphere/lower thermosphere (50-115 km) and in the stratosphere (10-40 km) by observing the Doppler shifts in the emission lines of an O2 atmospheric... 

Anemometry is a general term to represent the measurement of wind speed— anemos is the Greek word for wind. The earliest anemometer for meteorology is credited to Alberti in 1450. Hooke reinvented the device, which relied on cups or disks mounted on a pole that would rotate by the force of wind. Modern instruments to measure wind speed rely on laser Doppler shift, ultrasonic waves, propellers, and hot wire anemometers. The hot wire anemometer is commonly used for fluid flow measurements and in particular for research applications that require a detailed analysis of velocity in localized areas or for conditions... 

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