R to O update: Low Cloud and Fog

As of yesterday afternoon, the transition of the fog/low stratus (FLS) products to the AWC operations floor has been completed! Available within this suite is cloud phase, cloud thickness (i.e. fog/low stratus depth from base to top), IFR probability, and LIFR probability, and each of these is collected from GOES-E, GOES-W, and MODIS (Terra/Aqua polar orbiters).

Fog is a cause of significant air traffic constrains, particularly in coastal areas or regions of complex terrain, and the FLS product developed by UW CIMSS shows some marked improvement over the currently used BTD (3.9 - 11 micron) product in identifying these low ceilings.

Below is an example of these FLS products on the West Coast. On the morning of 120702, San Fransisco Center was reporting low ceilings and implemented a ground stop of inbound flights for much of the first half of the day. At 0745 UTC, the only planes getting into the center were the larger aircraft, those with more advanced instrumentation that allows for landings in very low visibilities. However, note that the routes at this time were being directed through the areas where the fog depth (cloud thickness) was the thinnest (purples and pinks) and the IFR probabilities the lowest (yellows and lighter oranges). Both products did a very good job in detecting the areas of dissipation within the low stratus deck and show the potential of this product in aviation operations.

120702 0745 UTC cloud thickness (fog depth), stations, and flight routes

120702 0745 UTC IFR probability and flight routes

 Another advantage to the new LFS products is the availability of this data from MODIS. While the passes from this instrumentation are scattered, the data is high resolution and shows details that are not caught by GOES-E/GOES-W. An example of this, taken from the Pacific NW, is shown below. At 1900 UTC on 120701, the GOES-W IFR probability (top) showed higher probabilities along the British Columbia Coastal Range as well as the Cascades and Olympics in WA, but the resolution only gave a general shading in the area. On the other hand, the MODIS IFR probabilities (below) are a 1 km resolution, and picked out the specific features of the terrain, the peaks and valleys.

While there are very few flight routes in this particular area, the potential of the higher resolution imagery in other areas of complex terrain, valleys prone to fog, or other areas in which there is heavy flight traffic can easily be seen.

120701 1900 UTC GOES-W IFR probability

120701 1902 UTC MODIS-CONUS IFR probability