At 0000 UTC June 9 (0 hour model time) a 1001 hPa low was located near 38S156E, and was near 38S157E at 1200UTC producing a strong southerly gradient over the area. A weak surface ridge lies to the north, from around 30S145E to 26S150E to 36S164E at 00 UTC 9 June. In 24 hours model time the low is expected to move further to the southeast to be near 39S161E. A southerly flow will persist between the low and a ridge further to the west at +36 hours at 20/30 knots. By +60 hours the new ridge pushes into the south of the area along around 40S. Strong to gale force winds at the surface and 850hPa will gradually become SE and ease to 15/25 knots by +48 hours. A similar flow pattern created by the low is evident initially at 700 hPa and 500 hPa, with winds easing and backing S/SE at +36 hours as the low moves to the east and gives way to a weak trough to the northeast of the area and S/SE winds weakening to around 20 knots by 36 hours. A secondary upper level circulation at 500 hPa is located near 28S147E at 12 UTC Saturday. Stronger northwest winds persist further east of the trough and low at 700 hPa and 500 hPa.
AU:ACCESS-G Global N144(~80km)/L50 (Hysplit currently using data on 29 sigma lvls) US: GFS Global T574(~27km)/L64 sigma/pressure hybrid vertical coordinate CA: GEM Global ~0.6 deg horizontal resolution
0500 m (1000 hPa): All models capture trajectory movement initially to northeast and then to the southeast over New Zealand. A slightly less eastward track is evident for the Canada trajectory towards the end. 1500 m (850 hPa): The Australian and US trajectory is initially to the northeast and finishes by returning back to the WNW for US and NW for Australian. Canada differs with a more south-easterly track maintained after the initial NE track. 3000 m (700 hPa): US and Canada have similar NE initial track and then southeast trajectory. Australia has a similar track to its 850 hPa and initially is to NE and then is towards the NW. Note: Trajectories represent material released from discrete levels. The limited number of trajectories displayed may be used to evaluate the general material flow beginning at each level, but should not be used to determine pollutant time-integrated concentration patterns or total deposition patterns, since these levels may not be representative of all interacting levels where pollutants are being transported, diffused, and deposited. The concentration/deposition model results and comparisons discussed below are a more appropriate guide for decision making.
AU:HYSPLIT4(includes dry and wet deposition) US:HYSPLIT4(includes dry and wet deposition) CA:MLDPO(includes dry and wet deposition)
All models show the highest concentration moving to the northeast by 24 hours and then spreading mostly to the southeast and reaching New Zealand at 24 to 48 hours. Australia differs in that the extent of concentration to the northeast is not as great as US and Canada initially (0-24 hours) and results in lighter concentration being moved towards the Australia coast under influence of differing upper level flow in the region from 24-48 hours and 48-72 hours. The 48-72 hours concentration levels are similar for US and Canada with continued southeast movement of the concentration, with Australia also showing movement to the southeast. But Australia differs with the NW movement of concentration towards over the coast. Some concentration moves along the eastern Australian coast to around 27S by 48 hours and to 25S by 72 hours and reaches around 147E with lighter concentrations. At the 72 hours step US and Canada remains off the Australian coast.
The main deposition flow is similar to the description of concentration movement above. The main deposition is to the northeast and then spreads mostly south-eastwards over New Zealand. Only Australian model has northwest deposition over the Australian continent.