Towards Implementation of TROPICS Data in NHC and JTWC Operations

Microwave (MW) imagery from polar-orbiting satellites provides critical information about tropical cyclone (TC) structure that is not available from visible and infrared (IR) sensors. MW data are routinely used by the TC operational forecast centers [e.g. National Hurricane Center (NHC), Central Pacific Hurricane Center (CPHC), and Joint Typhoon Warning Center (JTWC)] for multiple tasks, including TC center fixing, TC intensity estimates, and observing TC structure that is covered by clouds in visible and IR imagery. For example, MW imagery is used for detecting the formation of the eye that often becomes visible in MW imagery well before it is seen in the IR, and for detecting secondary eyewall formation.

This presentation will discuss several topics related to the possible operational use of TROPICS data. Specifically, we will present preliminary results on the intercomparison of TROPICS imagery from high-frequency channels, 183 GHz and 205 GHz, with the legacy MW imagery from low-frequency channels (37 GHz and 91 GHz) that are routinely used by the TC forecast centers. We will also discuss the implementation of TROPICS imagery in AWIPS2 and forecaster’s feedback on TROPICS data.

The constellation of five TROPICS cubesats provides the ability to view the same TC with a median revisit time around one hour and with high spatial resolution and from multiple viewing angles. aTROPICS has higher horizontal resolution compared to ATMS and AMSU (24 km for temperature channels and 16 km for moisture channels at nadir) and provides similar data. However, there are also some important differences. For example, TROPICS uses 118 GHz channels for temperature soundings, and has a 205 GHz channel (sensitive to ice scattering) that is not available on any operational MW sensors. The 183 GHz moisture channels are available on both TROPICS and ATMS, but are not currently used by the operational TC forecast centers. TROPICS sounder data also provides some information similar to MW imagers. However, TROPICS does not have a widely used 37 GHz channel, and the TROPICS 91 GHz channel has a resolution much coarser than legacy MW imagers (e.g. GPM GMI, AMSR2, SSMIS).