Ian Brooks Tethersonde mean meteorology from the high-Arctic ASCOS expedition 2008 Bolin Centre Database 2018 Datafile Atmosphere Weather observations ASCOS Meteorology High Arctic Arctic boundary layer Arctic clouds Tethered sonde profiles Earth science > Atmosphere Michael Tjernström 2018-10-16T14:24:39+00:00 English 1.0 None <p>Data structure contains 10-second averaged data (mean meteorology) from tethersonde on<br /> a continuous time-base. Where sonde is not flying all variables except time are padded<br /> with NaNs.</p> <p>TS10 = </p> <p>time: [132455x1 double] - matlab serial time<br /> P: [132455x1 double] - pressure (mb)<br /> T: [132455x1 double] - air temperature (deg C)<br /> RH: [132455x1 double] - relative humidity (%)<br /> Psurf: [132455x1 double] - surface pressure (mb)<br /> palt: [132455x1 double] - pressure altitude (m)<br /> Ts: [132455x1 double] - sonic temperature (K)<br /> WS: [132455x1 double] - mean wind speed (m/s)<br /> Traw: [132455x1 double] - uncorrected air temperature<br /> RHraw: [132455x1 double] - uncorrected relative humidity</p> <p>Poor ventilation of T/RH sensor resulted in a wind-speed dependent bias. A correction<br /> has been applied to match mean values to those of sensors on 15m mast. Uncorrected values<br /> are also given here. </p> <p>The sonic temperature (calculated from speed of sound measurement<br /> from sonic anemometer) has a significant bias high, by ~3 degrees. This is apparently a<br /> known issue with Gill sonic anemometers (at least older models). No attempt has been made to<br /> correct it here - while absolute values is biased, relative values within profiles should<br /> be OK.</p> <p>No wind direction is available as yet.</p> <p>Ian Brooks<br /> <a href=""></a></p> To obtain in-situ boundary-layer observations through a deeper layer, a sensors package was deployed hanging under a tethered balloon, and was quasi-continuously winched up and down in the ~0 – 600 m layer. These measurements were only interrupted when weather conditions with dense fog persisted for long periods of time since this was detrimental for the polar-bear watch. The winch was located in “Met Alley” (see Micrometeorology) which this was one (of two) reason why this site was continuously manned. The sensor package consisted of a Gill sonic anemometer in an aerodynamic housing and sensors for mean temperature and relative humidity, as well a sensor package movement and orientation. A CLASP aerosol sensors was also included but its inlet often froze up when the package was inside clouds. A camera set to take low-rate time lapse photos also hang under the tethered balloon. The data provided include one set of mean profiles and one set of TKE-dissipation rate; a measure of turbulence derived from the so-called inertial sub-range of wind speed power spectra.<p>Original address: <a href=""></a><br> </p> <p> Files:<br> <a href="/data/ascos/files/"></a> (3.68 MB)<br> </p>