Wednesday 27^th February

Our first flight!

Weather Outlook: (quoting Mel and Jon Egill) “a double vortex along a reverse-polar front”. Cold air outbreak from this weekend for a few days at least.

Flight plan for tomorrow: Map the two low pressure systems, one near Lofoten, one near Jan Mayen.

Blog

After a brilliant display of the northern lights last night our attention this morning was focused back to a lower part of the atmosphere as the flight planning team finalised the details of this today’s flight. The flight will study several things, firstly the winds off the coast of northern Norway. The aircraft will then fly through Hinlopenstretet (a narrow gap between the islands of Spitsbergen and Nordaustlandet where there might be high winds at low levels caused by the air being forced through a small gap) before landing in Longyearbyen on Spitsbergen to re-fuel and flying through the winds in the lee of Spitsbergen and returning to Andøya.

We want to get the data from the dropsondes into the forecast, and this process hasn’t been tested until today! How does this work? As the dropsonde falls through the atmosphere, collecting data on the structure of the atmosphere (temperature, winds, pressure and water content) it transmits this data back to the aircraft via a radio link. Once they receive all the data for one sonde onboard the aircraft they use a satellite phone to email this information to the Norwegian Met service, who put it onto the global telecommunications system so that the data is available to all the forecast centres. If the data is received by the forecast centres in time, then it is used to help make the forecast, which is started at around midday. We were happy to receive an email at 11:30 local time, confirming that the Norwegian Met Service had received data from the first sonde to be dropped. Unfortunately the data they sent was minus the latitude and longitude information, rendering it useless, and forcing us to try and decode the data sent to the GTS to work out what the format of the missing data should be. The Met Institute at Oslo managed to put the correct information in and re-send the information to the GTS, but as of 17:00GMT the data was not in the Met Office database. Tonight we have to try to work out why the data was missing in the first place – is it a problem with the sondes or the program used to send the data?

Continuing the food diary that I seem to have started, we had whale steak for supper, with potatoes and pea stew. This was my first taste of whale, and I have to report that it tasted good. The texture is more like beef than any fish I’ve ever eaten, and it is a reddy-brown colour. I was assured that it wasn’t an endangered species of whale that had been hunted, although we never did manage to successfully translate the Norwegian name for it. Apparently whale meat has become much less common in Norway; it used to be a ‘poor-man’s steak’ and people ate it regularly, but now it is much less common, maybe due to hunting restrictions imposed on Norwegian fisherman.

Weather Round-up

The forecasts from midnight show a well-defined front, oriented towards the south-east from the north-eastern coast of Greenland towards the northern Norwegian front. There is very strong wind shear across the front, of almost 180degrees, and also a thermal gradient and signature in the precip. field. A small low pressure system moves NE, interacting with the front, and makes landfall on Lofoten at about 6am on 28^th February. The HIRLAM 12km model puts 35kt winds (10m level) to the rear of the storm at this time, but the storm is weakening as it moves across the Lofoten. The 12Z forecast from HIRLAM and the global UM develops a second low further north along the front. This situation is interesting, because the air masses involved are the reverse of what you would usually expect: the cold Arctic air is south of the front and the warmer air is to the north. The low pressure system is now forecast to split into two during the night, and a second vortex spins up. The southerly vortex is predicted to move NE and die, as discussed, and the northerly vortex will move in a westerly direction.

The models are predicting barrier winds along the coast of Greenland, which has got Haraldur excited, and there was talk of sending the DLR off to Iceland tomorrow to sample them. There is also a nice tip jet developing – it’s a shame it didn’t happen last year, as we spent the whole campaign wishing for a tip jet!

It looks like we might see two polar lows on Monday (2^nd March), in an outbreak of cold air from the north. Conditions look good at the beginning of next week, with the Z500 field showing northerly winds bringing cold air southwards, to the west of Spitsbergen. Maybe the SV’s will also pick out this region as being sensitive.

SAP Evaluation

The ETKF SAPs again put the maximum in sensitivity to the north of Andenes, extending from the east coast of Greenland to Svalbard. This includes the most northerly of the split vortex low pressure system that we will probably target tomorrow. The SV SAPs put the main maximum in sensitivity to the west of the verification region, moving westwards with increasing optimisation time. These are in a region of strong mid-upper level flow into the verification region, to the south of a low pressure system which is decaying as it moves towards Scandinavia. There is a smaller maximum by the northern coast of Norway, around 15degrees east, to the north of the small low which will hit Lofoten tomorrow.