WRF Model created for the South China Sea

OWS has recently commissioned a new Weather Research and Forecasting (WRF) atmospheric model grid encompassing the entire South China Sea with a higher resolution sub grid covering the important offshore oil & gas industry region off the coast of northwest Borneo.

The early use of the model has shown some promising results. One example includes the WRF model identifying a local affect causing a plume of stronger winds near Palawan which has never been identified on coarser global atmospheric models. This local generation of winds was only previously noted by personnel offshore in certain synoptic situations, but could not be correlated with coarse global atmospheric modelling. It is now possible to forecast the region and length of time this wind, and subsequently generated waves, may affect clients working in the region.

The WRF Model is a next-generation mesoscale numerical weather prediction system designed to serve both operational forecasting and atmospheric research needs. It features multiple dynamical cores, a 3-dimensional variational (3DVAR) data assimilation system, and a software architecture allowing for computational parallelism and system extensibility. WRF is suitable for a broad spectrum of applications across scales ranging from meters to thousands of kilometres.

For more information on OWS modelling capabilities, please contact us through our contact link.

North Rankin B Installation assisted by OWS

Offshore Weather Services provided weather forecasting services during the installation of Woodside’s North Rankin B platform. The North Rankin jacket was installed in September 2011 with the topsides installed by float over several months later in March-April 2012.

The North Rankin B topside float over was the heaviest ever conducted in the southern hemisphere and required the services of the world’s biggest barge the Heerema No 1.

Offshore weather services were engaged by Heerema Marine Contractors Ned BV to provide weather forecasting services during the project which also required  an on-site  consultant  to provide daily briefings with the client, as well as issuing the site specific weather forecasts. In addition Heerema requested the model spectral data. Five sets of spectral wave data (each one produced from a different global  or high resolution mesoscale atmospheric  model) were uploaded to the client twice daily in order to run the client’s in house barge motion simulation software.

These simulations provided predictions of the motions and accelerations of the mating units of the North Rankin top sides to determine if the motions were within the limits acceptable to performing the float over operation. These predictions were then compared with measured data to provide increased confidence that the weather window for the  operation was well within project limits.

Peter Wellby, Offshore Weather Services Operations Manager and Certified Consulting Meteorologist was the onsite Duty Forecaster during the Heerema operations and was based on the HLB Hermod during the jacket launch, upending and placement on the seafloor. It was a reunion of old friends as Peter had last stood on the Hermod some 30 years earlier when the heavy lift barge was working in the North Sea.

 

North Rankin B

2022/23 AUSTRALIAN REGION TROPICAL CYCLONE SEASON OUTLOOK

At present negative sea surface temperatures (SST) anomalies meeting the La Niña threshold persist in the NINO3.4 region. Dynamic models have these anomalies persisting for the next month values rising from December, with nearly all models moving anomalies back into the neutral range by February. These conditions are expected to result in a slightly above average number of Tropical Cyclones (TC) over the Australian Region, with about 10 expected and 3-4 becoming Severe Tropical Cyclones (STC). Accumulated Cyclone Energy (ACE) is expected to be slightly below the long-term average across the northwest region and below the long-term average over the northern and northeastern regions.

For the whole Australian region (0 – 30S and 105 ‐ 160E), the total number of TCs in the Australian region should be slightly above the long-term average (although more significantly above the average for recent years), approximately 10 in total (range 6-12). Some of these may affect more than one area, with about 6-7 coastal impacts expected. The Accumulated Cyclone Energy index (ACE) is below the long-term average although close to average for recent years. The TC season should start mid-November and finish in late-May with most activity in February.

For the Northwest Shelf and Timor Sea (0-30S 105-125E), about 5 TCs (range 3-9) are expected which is slightly above average. The expected season will be mid November to late April. Three (3) to four (4) TC are expected to cross the coast.

Download full report: 2022/23 Australian TC Season Outlook