Mission Plan:
Primary Mission : None Alternate Mission: None Future Mission(s): Possible Intercomparison with Discoverer in vicinity of Cape Grim or overflight of Macquaries Is.Aircraft Operations
Take-off Time: N/A Flight #16: N/A Pre-flight Weather Briefing Time: Flight #16: N/A Updates: none Airborne Mission Scientist: Flight #16: N/A Mission Scientist: Flight #16: N/AShip Operations
Discoverer: Discoverer was on station near before midnight Friday and met up with Southern Surveyor to conduct intercomparison. Location of both ships was 48S, 145 29.5'E. Soundings are taken every six hours after 1200 23/11. The aircraft intercomaprison began approx. 0100 11/25. Aspecial raob was taken at 0300 UTC to support this effort. Detailed measurement values available on status page accessed below on catalog. Discoverer Lead Scientist: Tim Bates Southern Surveyor: Southern Surveyor position at 0000 UTC 25/11 is on station at Trans-P3 (45S 145 27'E). An intercomparison with the Disocverer occurred after 1500 UTC on 11/24. They will remain at station Trans P-3 for 30 hours. Soundings are being taken every 12 hours. See catalog reference below for detailed instrument status. Southern Surveyor Lead Scientist: Bronte Tilbrook
48 hour MSL P Prognosis is here
72 hour MSL P Prognosis is here
Latest Visible Sat Picture is here
Surface Wind 24-h forecast is here
GASP trajectory analysis is here
Synoptic Situaton at 00Z Saturday 26/11/95
Low 1000 hPa near near 43S 154E moving ESE at 10/15 knots forecast to be near 43S 157E at 12z tonight and weakening to be a peripheral system to a 992 hPa low near 40S 170E. Cold front associated with the low crossed Macquarie this morning and is now well east.
High 1022 hPa near 43S 140E moving E at 15/20 knots extends a ridge towards 55S 145E. High forecast to be near 46S 146E at 12z tonight, 49S 151E at 00z tomorrow and 50S 155E at 12z tomorrow night. The ridge is expected to lag the high, so that by 12z tomorrow night the ridge is likely to extend southwestwards from the high centre towards 60S 150E.
A significant trough is forecast to develop around 170E overnight and tomorrow, maintaining a fresh, cold SW stream through the Macquarie area.
A front is moving through southwestern Australia and this is forecast to be near a line 50S 134E to a low near 42S 136E to 35S 139E at 00z, moving SE at 25/30 knots. Trough forecast to be near NW Tasmania/50S 135E at 12z tomorrow night with a strong northerly pressure gradient to its south and east. A low is forecast to develop on the front near 50S 130E tomorrow night, moving clockwise around another, deeper low near 58S 123E.
Prognoses: 0-24 hours: The next 24 hours look relatively straight forward with the high moving through the ACE area and front to approach and crossing western parts of the ACE area on Sunday. The front is likely to be close to Cape Grim on Sunday night, preceeded by a strong northerly pressure gradient.
24-72 hours: The first front is likely to move through Cape Grim early Monday morning with another front to move into the area near 45S 135E by 12Z Monday night. The whole trough complex promises to be very complicated with lows forming in the area between 110E and 130E for the remainder of the weekend and into Monday. A series of weak fronts are likely to move out of the trough complex and cross the ACE area Sunday/early Monday, Tuesday and possibly Thursday.
FORECASTS:
Cape Grim: Weather: Fine until some showers develop tomorrow evening. Cirrus developing tomorrow morning. Wind: Southwest winds easing to 10/15 knots this evening and turning southeasterly. Winds becoming light and variable for a period overnight then east to northeasterly tomorrow morning before gradually increasing to 25/30 knots tomorrow afternoon. Winds easing to 15/20 knots tomorrow night just ahead of a late 15/25 knot west to southwest change. Macquarie Island: Weather: Showers continuing and falling as sleet or hail at times. Wind: West to southwest winds 20/30 knots with stronger squalls overnight, easing slowly later tomorrow.
R/V Discoverer Weather: Fine until some rain develops late tomorrow. Scattered cloud but broken cirrus developing tomorrow morning and broken middle level cloud developing in the afternoon. Wind: Southwest winds mostly 10/15 knots becoming variable below 10 knots overnight then northeasterly tomorrow morning. Northeasterlies increasing to 15/25 knots during tomorrow and reaching 25/30 knots later in the afternoon or during the evening ahead of a 15/25 knot northwest change late tomorrow night or early Monday morning. Seas below 1.5 metres increasing to 2 to 3 metres tomorrow afternoon and evening. Southwest swell 2 to 3 metres decreasing slightly overnight and tending west to northwesterly tomorrow.
R/V Southern Surveyor Weather: Fine until a little rain develops tomorrow evening. tomorrow Wind: Southwest winds mostly 10/15 knots becoming variable below 10 knots overnight then north to northeasterly tomorrow morning. Northeasterlies increasing to 15/25 knots during tomorrow and possibly reaching 25/30 knots late in the day or during the evening.. Seas below 1.5 metres increasing to 2 to 3 metres tomorrow afternoon and evening. Southwest swell 2 to 3 metres decreasing slightly overnight and tending west to northwesterly tomorrow.
REVIEW OF PREVIOUS DAY'S FORECASTS
A much better day forecast-wise, now that the low near Tasmania had been entered into the forecast calculations. The progs tried to move the low to the east too fast, but this was recognised as a fault with the models and the forecasts reflected this correction. As a result, southwesterlies over the ships have moderated and the weather has cleared as was forecast. Winds have remained strong at Cape Grim for longer than was expected, but the showers cleared on cue. The front moved through Macquarie as forecast with the weather also staying on track. The EC prog remained the only prog to recognise the low yesterday and was again, clearly the best product.
Reporter: Barry Huebert
There will be no C-130 flight on Sunday. We will use the day to open the belly of the C-130 to attach a cable to another potential antenna for the balloon receiver (which as yet has _not_ worked with the device we found to test it) and to repair a cooling-water pump on the NH3 system.
We will also hold a science meeting at 2 PM. Each PI will be given 5 minutes to show some interesting data. Many will focus on flights 11 (mostly clear, cold sulfur chemistry) and 12 (solid stratoQ), but any data will suffice to start the discussion. From this we hope to at last fax or email figures or tables to the other platforms with some C-130 data. Most groups have been so busy flying or repairing things that they haven't worked much data up.
Monday we are looking at the posibility of doing a series of stacks upwind of Cape Grim, while Disco is on station there. The problem is that a series of small lows will be spinning through that area for the next 5 days or so, and we will need to see if we can sandwich this flight into westerly flow, between the other two possibilities: lousy weather and winds from the north. That series of storms will prevent us from thinking about any Lagrangian experiments for the next week, by the way.
As the monster low near Antarctica moves cold air closer to us in 3-4 days, we may again have the potential to fly in the outflow of 15,000-18,000' cumulus clouds. It really appears from yesterday's flight that those may be a major source of the layers of large number concentrations of nanometer particles that Tony saw in GLOBE and the C-130 has seen during ferry flights. Figuring out how to investigate those layers and their source in Cu is becoming a major objective.
The other high-priority thing we are watching is for the arrival of drier northern air at Macquarie Island. If this develops, it will give us a chance to visit Macquarie at a time when it isn't raining. Although rain is the norm there, it introduces so much heterogeneity into the air that we would lose the value of an intercomparison of DMS and microphysical measurements. The arrival of the drier air has slowed down a bit, so the flight opportunity may come Tuesday or Wednesday. If so, we will definitely plan to make our flight to do a vertical stack near the island.
Finally, we have asked that Disco manage to get one of the balloon transmitters ashore, perhaps with a Zodiac, while they are near Cape Grim. We feel strongly that only by having one of these transmitters to use near the C-130 and to put on a hill during departures and landings can we assure ourselves of the integrity of the tracking system. Dozens of transmitters on the ship won't help us do Lagrangians if we can't be assured that the reciever is working, so we will bring one ashore to use for testing. Since these were custom-built by Randy Johnson, the entire world's supply is currently aboard Disco.
