Day: 320 (16 November 1995)
Mission:
Primary Mission : none scheduled Alternate Mission: N/A Future Mission(s) : possible Saturday (18 Nov 95) flightAircraft Operations
No mission scheduled. Take-off Time: Pre-flight Briefing Time: N/A Updates: N/A Airborne Mission Scientist: N/A Mission Scientist: N/AShip Operations
Discoverer: Discoverer in route to Macquarie Island. Discoverer Lead Scientist: Tim Bates Southern Surveyor: Southern Surveyor to drop off passengers at Research Point at 0700UTC (1800 LDT today). Then will be in route to Cape Grim. Southern Surveyor Lead Scientist: Bronte TilbrookSystems Status:
Aircraft: Work continues on aircraft systems and instruments after successful ferry. Effort focussed on PMS, Lidar and ammonia sensors. Discoverer: All major systems on Discoverer are operational. Ammonia being worked on. So. Surveyor: All major systems operational on Southern Surveyor. Cape Grim: Cape Grim installation continues. Most systems operational and work continues on SO2 ammonia and mass spectrometer. ISS system has faulty OMEGA receiver.
GASP trajectory analysis is here
Synoptic Situaton at: 00Z Thursday 16/11/95:
Low 1008 hPa near 41S 162E moving east at about 20/25 knots forecast to be just east of NZ by 12z tonight.
High 1025 hPa near 40S 143E moving east at 20 knots forecast to be near 37S 159E at 00z tomorrow extending a ridge to 50S 155E and 55S 147E. The high is forecast to be near NZ around 12z tomorrow night with the ridge to the south weakening significantly. Low about 980 hPa near 57S 158E moving eastwards at about 40 knots. Low 1008 hPa near 36S 123E moving SE at about 20 knots forecast to be near 42S 130E at 12z tonight with central pressure about 1004 hPa , 47S 145E at 12z Friday night, central pressure 996 hPa but with possibly multiple centres around that position. The low is expected to weaken during the following 24 hours and move rapidly east to near 51S 172E by 12Z Saturday night.
Prognoses:
The progs have now started to converge with regards the formation and development of the low south of Western Australia. Yesterdays GASP may have picked up some crucial local data that the other global models missed, resulting in it doing a better job than was first thought. The EC and US models both now move the low southeastwards past Tasmania on Saturday as listed above, in contrast to yesterdays run where they stalled the low in the bight. A high following this low is expected to move into the area around 42S 130E on Saturday and this is likely to remain in the area around Tasmania for the remainder of the weekend and into Monday, when it is expetced to move over the Tasman Sea.
Verification of yesterdays forecasts:
Discoverer: Reported westerly winds to 30 knots this morning which appears to be near the front and was much as forecast. Weather appears to be better than forecast with large clear areas evident on the sat pix.
Cape Grim: Southwesterly winds have moderated somewhat during the day but have not yet moved into the north. The weather is fine as forecast.
Forecasts:
Discoverer: Weather: Fine until a few light showers or drizzle patches develop tomorrow morning and increase south of 50S.
Winds: Chiefly westerly winds 20/25 knots tending northwesterly tonight and easing a little tomorrow moring as you near the ridge axis. Winds may shift northerly late tomorrow as the low nears you. A front with associated SW change is forecast to cross you on Saturday morning. Seas around 2 to 3 metres. Westerly swell to 4 metres.
Cape Grim/Southern Surveyor: Weather: Fine. Some cirrus cloud at times, increasing tomorrow. Winds: Southwest winds 10/15 knots turning northwest to northeasterly tonight and locally E/NE'ly at Cape Grim station. Winds increasing to 15/25 knots tomorrow morning but easing late in the day as they shift back to the northwest.
Sender: Barry Huebert
There will be no flight on Friday, 17 November, so that the lidar, PMS probes, NH3 system, and other instruments can be repaired. Most systems should be ready to fly on Saturday.
The present forecast for Saturday suggests that conditions may not be suitable for either of the flights being considered. One is a stratocumulus flight, to evaluate radiative properties of stratoQ and their relationship to microphysical measurements and the aerosols below cloud. This would involve flying several circular patterns below and within the cloud, as well as lidar legs above and porpoising across the inversion.
The other likely flight plan is a study of DMS branching in cold air, with column closure legs included. there is a very cold, dry airmass that will be within a few hours flying time of Hobart on Saturday or Sunday. We would sample it from mid-morning to mid-afternoon to observe the photochemical loss of DMS and see what fraction of the products showed up as SO2, NSS, and MSA. This outbreak of 0 to -2 degree dry air is very rare this time of year, and is an opportunity that we don't want to miss for testing DMS oxidation hypotheses.
A decision on Saturday or Sunday flights will be taken at Friday's meeting.
