SA31D-2360
Aurora Activities Observed by SNPP VIIRS Day-Night Band during St. Patrick’s Day, 2015 G4 Level Geomagnetic Storm
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Tung-Chang Liu1, Xi Shao1, Changyong Cao2, Bin Zhang3, Shing F Fung4 and Surja Sharma5, (1)University of Maryland College Park, College Park, MD, United States, (2)NOAA College Park, College Park, MD, United States, (3)Cooperative Institute for Climate and Satellites University of Maryland, College Park, MD, United States, (4)NASA Goddard Space Flight Ctr, Greenbelt, MD, United States, (5)University of Maryland College Park, Montgomery Village, MD, United States
Abstract:
A G4 level (severe) geomagnetic storm occurred on March 17 (St. Patrick’s Day), 2015 and it is among the strongest geomagnetic storms of the current solar cycle (Solar Cycle 24). The storm is identified as due to the Coronal Mass Ejections (CMEs) which erupted on March 15 from Region 2297 of solar surface. During this event, the geomagnetic storm index Dst reached -223 nT and the geomagnetic aurora electrojet (AE) index increased and reached as high as >2200 nT with large amplitude fluctuations. Aurora occurred in both hemispheres. Ground auroral sightings were reported from Michigan to Alaska and as far south as southern Colorado. The Day Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advancement in night time imaging capabilities. The DNB senses radiance that can span 7 orders of magnitude in one panchromatic (0.5-0.9 μm) reflective solar band and provides imagery of clouds and other Earth features over illumination levels ranging from full sunlight to quarter moon. In this paper, DNB observations of aurora activities during the St. Patrick’s Day geomagnetic storm are analyzed. Aurora are observed to evolve with salient features by DNB for orbital pass on the night side (~local time 1:30am) in both hemispheres. The radiance data from DNB observation are collected at the night sides of southern and northern hemispheres and geo-located onto geomagnetic local time (MLT) coordinates. Regions of aurora during each orbital pass are identified through image processing by contouring radiance values and excluding regions with stray light near day-night terminator. The evolution of aurora are characterized with time series of the poleward and low latitude boundary of aurora, their latitude-span and area, peak radiance and total light emission of the aurora region in DNB observation. These characteristic parameters are correlated with solar wind and geomagnetic index parameters.
