The Visible Infrared Imaging Radiometer Suite (VIIRS) is one of the five instruments on-board the Joint Polar Satellite System (JPSS) Suomi National Polar-Orbiting Partnership (S-NPP) satellite. VIIRS has sixteen Moderate Resolution Channels (M-Band; 750 m resolution at nadir), five Imaging Resolution Channels (I-Band; 375 m at nadir), and a Day-Night Band Channel (DNB, 750 m across the scan, nominal bandwidth from 500 to 900 nm). VIIRS' DNB channel is a successor to the Defense Meteorological Satellite Program Operational Linescan System (OLS). The radiances detected by the DNB span over eight orders of magnitude. DNB produces visible-like imagery at night using illumination from the moon, auroras, anthropogenic sources, and night glow. The unique DNB data have multiple applications for the tropical cyclone (TC) analysis and forecasting and can be critical for operational forecasters. The DNB's nighttime capabilities are especially important for weaker TCs that tend to be less organized, have multiple circulation centers, and are generally more difficult to locate. For example, DNB imagery can be used to determine the presence of the eye in the cases when the eye is small or is being obscured by thin cirrus and not obvious in infrared (IR) imagery. DNB imagery can also be used to perform center-fixing and has been used by forecast centers to refine nighttime storm center locations. The DNB has also proven especially useful for sheared systems when the low-level circulation center is exposed and/or elongated and is hard to determine from the IR imagery or animations of IR imagery.
An experimental real-time application displaying storm-relative VIIRS DNB, visible, and IR imagery in the vicinity of TCs has been developed and has been available on the CIRA TC Real Time page (http://rammb.cira.colostate.edu/products/tc_realtime/) since January 2014. More recently, in October 2014, the low-latency DNB imagery also became available to CIRA. The low-latency, storm-centered VIIRS imagery from the CIRA TC Real Time Page, which in some cases produces better results compared to Near Constant Contrast (NCC) imagery, has been utilized in the National Hurricane Center (NHC) Proving Ground and has shown utility for TC analysis. Multiple examples of the use of VIIRS DNB imagery for TC analysis will be presented. In addition, current limitations of the TC-centered imagery, ways to overcome these limitations, and additional ways of using the DNB to improve TC analysis will be discussed.
Disclaimer: The views, opinions, and findings contained in this article are those of the authors and should not be construed as an official National Oceanic and Atmospheric Administration (NOAA) or U.S. Government position, policy, or decision.