Mission Plan:
Primary Mission : none Alternate Mission: N/A Future Mission(s) : Engineering flight Tuesday PM 21 November. No flight operations on Wednesday 23 Nov. Possible Lagrangian mission comencing Thursday 24 Nov. **Special Notice** A meeting will be held at 9 AM on Wed. 23 Nov.in Arrivals area to discuss details of the Lagrangian series of flights.Aircraft Operations
Take-off Time: N/A Pre-flight Weather Briefing Time: N/A Updates: N/A Airborne Mission Scientist: N/A Mission Scientist: N/AShip Operations
Discoverer: Discoverer in route toward initial point for Lagrangian at 50S 135E. 1900 UTC 11/21 position was 47S 147E. Detailed measurements samples available on catalog. Discoverer Lead Scientist: Tim Bates Southern Surveyor: Southern Surveyor Has departed thrid station (42S, 140 E) for forth station in survey cruise. Soundings being taken every 12 hours. All other instrumentation in good order. Southern Surveyor Lead Scientist: Bronte TilbrookSystems Status:
(Detailed Description) Aircraft: Engine change underway in Hobart. Expect engineering flight by Tuesday evening and power for PIs on Wednesday morning. Discoverer: All major systems on Discoverer are operational. So. Surveyor: All major systems operational. Cape Grim: All systems are operational. The ISS has operational OMEGA and profiler. RASS system is down. Macquarie Island: Most systems operational. Six hourly soundings are being taken. Installation and checkout continues on new instruments
48 hour MSLP Prognosis is here
72 hour MSLP Prognosis is here
Latest Visible Sat Picture is here
Surface Wind 24-h forecast is here
BMRC Hysplit trajectories are here
GASP trajectory analysis is here
ACE-1 FORECAST
Synoptic Situaton at: 00Z Tuesday 21/11/95:
High 1024 hPa near 47S 151E moving steadily eastwards, forecast to be near 45S 161E at 00z tomorrow and over NZ tomorrow night.
1008 hPa low near 42S 137E moving east at 15 knots forecast to be near 43S 145E at 00z tomorrow and over Tas 12z tomorrow night.
High 1024 hPa near 37S 122E moving east 15 knots, forecast to be near 35S 130E at 00z tomorrow and 36S 133E at 12z.
Front near 50S 123E/42S 120E moving east at 25 knots forecast to be near 50S 138E/46S 133E at 00z tomorrow and weakening whilst slipping southeastwards.
A siginificant low forecast to approach 55S 110E by 00z tomorrow.
Prognoses:
0-24 hours:
The models have been consistent pushing the low close to Tasmania's west coast by 00Z tomorrow and then slowly over the state during the afternoon. The approaching front is weakening and is not likely to be a terribly significant change as it moves through the Discoverer's area..
24-72 hours:
A significant difference is apparent between the GASP model and the EC/US models in the timing of the front through the 50S 135E area. GASP is slower in its movement of the front and would move it through the area during Thursday afternoon. However, the EC/US model scenario would have the front through the area during the morning.
A possible explanation for this discrepency, is the nature of the front or fronts. At this time, the models may not necessarily be able to resolve a situation where there may be more than one front in the system and so may have seized on one front and run with that. As a result, the higher resolution models may offer the better guidance, although at +72 hours, even these may be somewhat suspect.
We have decided to show the GASP run on the attachments.
FORECASTS:
Cape Grim:
Weather:
Showers increasing tonight with the chance of a thunderstorm overnight and tomorrow morning. Showers easing tomorrow afternoon.
Winds:
East to northeast winds 25/35 knots easing to 10/20 knots overnight and turing west to southwesterly tomorrow morning. Southwesterlies freshening to 15 to 25 knots later in the day.
Macquarie Island:
Weather:
Drizzle and showers easing overnight but increasing again during the day. Winds: West to northwest winds 15/25 knots increasing to 20 to 30 knots tomorrow.
R/V Discoverer
Weather:
Some light showers and drizzle developing this evening and increasing as the front crosses around the middle of the day.
Winds:
Northeast winds 10/20 knots becoming variable below 15 knots overnight then northwesterly tomorrow morning. Winds increasing to 15/25 knots tomorrow ahead of a northwest to westerly change of similar strength around the middle of the day. Seas to 2 metres increasing to 2 to 3 metres near and following the front tomorrow. Southwest swell around 2 metres.
R/V Southern Surveyor
Weather:
Showers and the chance of a thunderstorm, gradually easing tomorrow morning to just a shower or two in the afternoon.
Winds:
East to southeast winds 15/25 knots gradually tending southeast to southwesterly as the low moves past to the north of you tonight. Chiefly south to southwest winds 15/20 knots tomorrow, possibly reaching 25 knots in the afternoon. Seas to 2.5 metres. Southeast and southwest swells to 2 metres.
There will be no flight on 22 November. Numerous C-130 PI's need time to work on their instruments to ensure that they are ready to fly on Thursday, 23 November. We will probably have good ammonia measurements by Thursday.
We hope to be able to start a Lagrangian experiment on Thursday. Although it is a bit early still to say exactly what the conditions will be on Thursday, it appears that a front will pass 135E 50S sometime between sunrise and early afternoon. Since the clearing behind that front will take a few hours, balloons could be launched from Disco into that clear air and the C-130 could join them immediately for our first Lagrangian flight. The Disco appears to be in an excellent position to support the launch, and the Southern Surveyor will also be quite near the likely track.
By tomorrow we will have the first forecast trajectories for this area, which will allow us to suggest refinements in the start time and launch position. Thus, by midday Wednesday we will suggest a rough positon and time, and by 6 PM Hobart time will have a refined start time and location.
Considerable discussion has centered on the most desirable time for the flights, since we will only be on station for between 4 and 6 hours in each 12 hour period. Should that station time include sunset and sunrise, to catch the changes as the sun turns on and off, or would it be better to include noon and midnight, which would give us the biggest changes in photochemical activity? The largest DMS changes, for instance, occur at midday when the sun is highest. But sunrise in particular marks a huge change in the availability of oxidants, including OH and possibly chlorine radicals. Due to the fact that we have only one airplane and it has to ferry a substantial fraction of each flight, we cannot get both sunrise and noon on the same set of Lagrangian flights. We can choose one window for this Lagrangian sequence and the other the next time we have an opportunity, though.
A meeting will be held at 0900 local on Wednesday to consider the scientific pros and cons of the various observation windows. At that time we will hopefully also have a better idea of when the clear air will arrive in the region we can conveniently reach with 4 hours on station. A preliminary decision on a start time will be made at the 2 PM planning meeting, subject to changes in the forecast trajectories.
