96/04/24 CART site activity

Meteorology at the Central Facility


Weather Conditions from Site Operators Log

Visiting Instruments at Central Facilities


CART Instrument Operations at Central Facilities


Key: O = operational, X = down or degraded

CART Instrument Operations at Boundary Facilities


There are four staffed Boundary Facilities, each having Balloon Borne Sounding Systems (BBSS) and MicroWave Radiometers (MWR). During the IOP period, sondes are launched every three hours round the clock, starting at 5:30 GMT (12:30 CST). The sites are listed below. Times listed following a site indicate questionable data or failed sonde launches. Weather conditions are recorded in the Boundary Facilities Site Operator's Log.

CART Instrumentation at Extended Facilities


There are numerous unstaffed Extended Facilities. The specific instrumentation at the extended facilities varies from site to site, but generally includes a flux station (either an Energy Balance Bowen Ration (EBBR) system or an Eddy Correlation (ECOR) system), a Solar and InfraRed Observing System (SIROS), and a Standard Meteorology Observing Station (SMOS). For the locations of the Extended Facilities, and their suite of instrumentation, see the table and map of the Extended CART site. The comments below indicate specific data streams with identified problems.

Key Comments/Observations related to flights

Variable thin to thick cirrus fibratus, generally tow layers from 7.5 km to 14 km. The DC-8 generally created persistent contrails only in connection with existing contrails.

CART-site observations (04/24):

Very windy (SW-direction) and dusty (blown up soil)
Cirrus clouds mainly above 10km altitude
Cirrus about 2 km thick, occasional concective cells without a bottom, then less humid sections, only a few halos events were sighted
Winds at cloud level 300/50kn turning northerly with altitude
No mid-level and no low-level clouds

DC-8 overpasses over the CART site (times in UTC):
17.17 SE-NW overpass, 30Kft
17.38 NW-SW overpass DC-8 laying contrail, sampled by T-39, 26Kft, sampling at the bottom of a convective cell (tops at 14km!)
17.48 thick cell 8-14km direct over the site (lidar)
18.05 another aircaft to north lays a (in clouds only) contrail
18.08 another aircraft passing to the south (picture of 4min con)
18.12 weak halo, lot of uncinus structure to the south
18.22 SE-NW overpass, contrail in cloud 10min later (no T-39)
18.38 NW-SE overpass, non-persistent contrail (no T-39)
18.58 SE-NW overpass, non-persistent contrail
19.15 dog-fight of two trainers over the lidar
19.19 NW-SE overpass, picture sequence of growing contrail,
contrail moved faster than the cirrus below (wind shear!)
19.40 cirrus clearing out, replaced by a dryer air-field
19.59 SE-NW overpass, non-persistent cirrus, longer lasting near cirrus fields only (easily identified by the bubbly structure and an often brighter appearance
for 20 minutes: looping just W of the CART site at different altitudes: from 20.07 on no visible contrails
20.25 leaving the CART site to SE, no contrails, visually lost
20.45 SE-NW overpass no contrail
21.07 NW-SE overpass
21.30 SE-NW overpass, making contrails, persistent near clouds
21.52 NW-SE overpass, passing upwind-leg contrail to the north
22.10 notice DC-8 laying contrail over the dryer patch downwind about 50 miles out
22.17 SE-NW overpass, non-persistent contrail, weaving off line, in thicker cirrus deck to the north and soon lost
22.37 NW-SE overpass, in heavy cirrus, hardly visible brightening
22.50 dark line above the horizon to the east: aerosol layer?
23.10 SE-NW overpass north of CART, cloud cover is dense and the overpass as well as the spirals remained undetected

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