![GOES-15 Water Vapor (6.5 µm) images, with pilot reports of turbulence [click to play animation]](http://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2017/05/960x1280_WESTL_B3_GOES15_WV_EPAC_DIV_PIREPS_23MAY2017_2017143_110000_0001PANEL.GIF)
GOES-15 Water Vapor (6.5 µm) images, with pilot reports of turbulence [click to play animation]
An interesting linear feature appeared over the East Pacific Ocean on GOES-15
(GOES-West) Water Vapor (6.5 µm) images
(above) on 23 May 2017, which at first glance immediately nominated it for the “What the heck is this?” blog category. A contrail was ruled out, since it was not oriented along a common or busy flight route — so potential large-scale dynamic processes were briefly investigated. Since the linear feature was perpendicular to the busy California/Hawaii flight route, pilot reports of turbulence are plotted on the water vapor images; two reports of light turbulence at altitudes of 33,000-34,000 feet (at
0918 and
1109 UTC) appeared to be close enough to have possibly been related to the linear feature.
![GOES-15 Water Vapor (6.5 µm) images, with contours of satellite wind derived upper-level divergence [click to enlarge]](http://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2017/05/170523_goes15_water_vapor_upper_level_divergence_anim.gif)
GOES-15 Water Vapor (6.5 µm) images, with contours of satellite wind derived Upper-Level Divergence [click to enlarge]
Satellite atmospheric motion vector (AMV) derived products such as Upper-Level Divergence
(above) calculated at 3-hour intervals (
source) revealed an area of divergence focused near the area of the linear satellite image feature — around 30º N, 140º W, at the center of the images — which reached its peak intensity at
12 UTC; this suggested that the feature may have formed along the axis of the sharp deformation zone between two upper-level lows over the East Pacific Ocean (
mid/upper level winds |
200 hPa Vorticity product).
![GOES-15 sounder Water Vapor (6.5 µm, top; 7.0 µm, middle; 7.5 µm, bottom) images [click to enlarge]](http://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2017/05/170523_goes15_sounder_water_vapor_anim.gif)
GOES-15 sounder Water Vapor (6.5 µm, top; 7.0 µm, middle; 7.5 µm, bottom) images [click to enlarge]
Unfortunately, this region was not within the view of Himawari-8 or GOES-16 (each of which provide 2-km resolution water vapor imagery at 3 atmospheric levels). However, the GOES-15
sounder instrument has 3 similar water vapor bands
(above) — albeit at a more coarse 10-km spatial resolution at satellite sub-point — which showed the linear “deformation axis cloud signature” at all 3 levels of the atmosphere. The GOES-15 sounder water vapor
weighting functions for a “typical” US Standard Atmosphere are shown below.
![GOES-15 sounder Water Vapor band weighting functions [click to enlarge]](http://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2017/05/goes15_sounder_water_vapor_weghting_functions_USSA.jpeg)
GOES-15 sounder Water Vapor band weighting functions [click to enlarge]