Observations of Lower Tropospheric Water Vapor Structures in GOES-16 ABI Imagery

摘要

During the afternoon of 16 April 2017 over Durango, Mexico, Geostationary Operational Environmental Satellite (GOES)-16 Advanced Baseline Imager (ABI) imagery near 1.38 and 7.34 μm exhibited nonstationary banded features. Alternating patterns of bright (dry) and dark (moist) bands were evident in images of 1.38-μm reflectance, while corresponding warm (dry) and cool (moist) bands were evident in images of 7.34-μm brightness temperatures. Based on observations, ambient southwesterly flow across the region is hypothesized to have channeled water vapor through major valleys over western Durango, followed by terrain lifting of water vapor over the plateau of central Durango. Due to lifting, moist bands appeared relatively cool in imagery near 7.34 μm. Similar bright and dark banded patterns were also evident in ABI imagery over Chihuahua, Mexico, on 8 May 2017. During the afternoon over Chihuahua, broken linear segments of cumulus formed within moist portions of the bands. Imagery from the 12.3- to 10.3-μm split window difference also supported the presence of moist bands. In the 8 May 2017 case, the banded features are hypothesized to be the result of horizontal convective rolls. Observations suggested that dark (moist) bands in imagery near 1.38 μm corresponded to the rising branch of horizontal rolls. Due to vertical motion, broken linear segments of cloud streets formed within the rolls. One consequence of newly identified features of the clear-sky water vapor field indicated the importance of new ABI measurements to aid forecasters in their interpretation of complex mesoscale dynamics.