Decline of the golden age of passive microwave imagers

Since the early 1990s, there has been a near-continuous constellation of passive microwave imagers observing the earth from low earth orbits. Observations from these frequencies can peer through clouds to provide novel information not provided by other measurements. In the presence of significant cloud liquid and ice water, microwave radiometry can provide structural information about droplet/ice size, concentration, volume, and precipitation intensity. At longer wavelengths, detailed information near the ground – including surface wind from ocean roughness, vegetative and land surface properties, and polar surface ice characterization – can be yielded. Despite these benefits, the peak of passive microwave imager information may have been attained.

This presentation will briefly discuss the history of passive microwave imager observations, the constellation and available historical data, as well as the prognosis for current and upcoming missions. The capabilities of past, present, and future sensors as visualized by analysis products will be shown. While there are a variety of applications for passive microwave radiometry, this presentation will focus on their application to tropical cyclone analyses and the associated 20 year history of near-real time demonstration on the Naval Research Laboratory Tropical Cyclone Demonstration web page (NRL TC web).