Daily Summary for 5 December 2006

Another weak low moved across the area during the overnight hours, enhancing the lake effect snows and providing cloud cover in multiple layers.

The flight targeted the ~2:30 LT descending CloudSat overpass near CARE as well as a descending NOAA-16 (AMSU) overpass one hour earlier. A detailed synopsis of Larry's flight notes can be found below. Suffice it to say that we were profiling mixed phase clouds below the ground track when CloudSat passed overhead and sampled them in situ afterward. Except for some patchy coverage, the mixed-phase CloudSat overpass last night was a very good case for CLEX.

Enroute to CARE ground site at 20,000 ft, the lidar and Ka-band radar showed likely liquid/mixed phase signatures at cloud top with ice below (i.e., narrow bright layer in lidar and cellular structure with larger grad[Z] at top and weaker signal below). Lidar bright layers were found at different altitudes and were spotty in horizontal coverage. This would not be a pervasive mixed phase cloud shield east and north of CARE.

Over CARE by about 06Z, cloud field was less in coverage and vertical extent. From lidar, Ka-band radar, and probes, the cloud over CARE appeared to be mostly layered ice cloud below about 3000 m MSL. Ground based W-band radar confirmed same and was largely consistent with Ka-band Convair radar. Level flights and spirals were executed over CARE. Air-to-ground communication with new ground radio was very good.

Radiosonde balloon was launched just prior to 06z. By about 0640Z, Convair was on its way to CloudSat track staying level at 1600 m MSl or so (bottom of last spiral and minimum altitude).

Maintained 1600 m MSL and headed 'north' on CloudSat track. Ka-band showed more cellular structure at cloud top with fall streaks below after leaving CARE with tops around 3200 m MSL and lower in some locations. Ice in probes (CIP down; 2D-C fine). We turned and ascended by 0656Z. We hit liqiud in a lower cellular layer at 1900 m MSL near top of echo - confirmed mixed phase - on the way up to 20,000 ft (6 km or so). We headed 'south' on track and profiled cloud with lidar and radar. Ka Radar showed nice cellular structure at cloud top at 2000-2200 m MSL. Lidar showed bright layers in same location - likely mixed phase. Toward southern part of domain, lidar and radar structure changed to more layered and weaker appearance - likely ice. Howard noted that ice cloud transition was over a lake. Turned by 0714z to head back 'north' at 20,000 ft again. By 0720, lidar seeing steady aerosol layer from 3500-3700 m - likely from long range transport according to Kevin. By 0725 on track heading north. By 0731:30, lidar showed bright layer in lidar at cloud top. Layer altitude varied from 2200 m to 1600 m. Looked like good mixed-phase/liquid top during overpass from lidar view. By 0745, Convair descended and turned to porpoise cloud layer below. Ka-band picked up nice cellular structure at cloud top as we got closer (more sensitivity) with likely ice fall streaks down to ground in spots. Very nice generating cells in Ka-band between 0748-0750 at 2100 m to 1600 m MSL. Peak Z just below top in cells was 2-6 dBZ. By 0757, we were porpoising clouds and confirmed mixed phase at top with 0.2 g/m3 peak LWC and dendrites and stellars. Other LWC peaks at 0.1 g/m3 at/near cloud top. Toward southern part of domain, cloud turned to all ice again with lower echo tops. By 0810z, we turned northward again and porpoised same vertical box. By 0817-0819z, we were back in water cloud with peak around 0.1 to 0.2 g/m3. Nice generating cells in Ka-band at 0821z with 6-10 dBZ peak Z.

Heading east now at same blocked altitude (4-7kft) for porpoise toward Ottawa. Between 0825-0830z, nice profile in Ka with cells, LWC up to 0.2 to 0.3 g/m3, turbulence passing through, ice imaged in probes, fall streaks of ice to ground. Another very robust mixed phase cell around 0838z. Total water content reached up to 0.5 g/m3 with as much ice as liquid. Radar showed generating cell and we hit turbulence too. dBz topped out at 10 dBZ in cell. Stellars in 2D-c imagery. By 0842, clouds more layered, lower dBZ in radar, all ice in probes. Some clouds above flight altitude. Clouds choppy and wispy on radar as we headed back to Ottawa at low levels.