Ocean Observing and Climate

Recent AutoFlux data from RRS Discovery

Contact: Margaret Yelland or Robin Pascal

*** September 2007 *** AutoFlux has now been removed from Discovery since the SEASAW and DOGEE cruises have been completed.

Ship Position On the left is the cruise track since March 2006. The red star marks the ship's current position. A close-up of the last 10 days is shown on the right.

AutoFlux data from the Discovery are sent daily. The daily messages contain one sample per hour, averaged over a 15 minute period.

NOTE The data displayed here have NOT been quality controlled, and data obtained while the ship was in port have not been removed. Apparent periods of absent data may be caused by communications problems with the iridium system.

The larger of each pair of plots shows data obtained over the last 10 days. Click to enlarge. The smaller of each pair shows data obtained since March 2006. Again, click to enlarge.

Speeds (m/s) Red - true wind speed corrected to 10 m and neutral stability (the corrections require a number of mean meteorological and navigation parameters, so if any of these are missing the true wind will also appear absent). Blue - wind speed as measured (no corrections). Green - ship speed over the ground. 1 m/s is roughly 2 knots. See these Met Office pages to convert from wind speed into "Force xx" on the Beaufort scale.

Directions Red - ship's heading (degrees to). Green - true wind direction (degrees from). Blue - wind direction relative to the ship (wind on bow = 180)

Temperatures (deg C) Dark blue - air temp from the NOC psychrometer. Red - air temp from the NOC Vaisala. Green - wet bulb temp from the NOC psychrometer. Purple- air temp from the ship's Vaisala sensor. Light blue - sea surface temp from the ship's thermosalinograph.

Relative Humidity (%) Blue - from the NOC Vaisala. Green - calculated from the wet and dry bulb temperatures from the NOC psychrometer. Red - from the ship's Vaisala. Note - when the water reservoir for the psychrometer's wet bulb dries out the calculated humidity becomes roughly 100%.

Air pressure (mb) Data from a sensor at about 17 m above sea level (not height-corrected).

Total Downwelling Short Wave (W/m2) From one of the ship's TIR sensors.

Heat Fluxes (W/m2) Bulk estimates of the sensible (blue) and latent (green) heat fluxes. Red - measured latent heat flux.