Saturday 15th March


Praying for polar lows


Weather Outlook:  Possible polar lows moving south from near Spitsbergen.

Flight plan for tomorrow: Measure fluxes near Spitsbergen.  Map polar low or trough depending on what develops overnight.




Well first thing this morning it was pretty miserable here.  The only polar low visible in the satellite images was in the Russian sector, and it looked to be staying put there.  It also spent the greater part of the morning raining – the first time it’s been warm enough for the precipitation to fall as rain not snow.  I had my ‘end of campaign interview’ with Astrid and Frode before lunch.  I still hate being put on the spot although Astrid is a friendly interviewer and tries to make it easy for you.  The documentary that they are making about our hunt for a polar low will be broadcast on Norwegian television around Christmas time, so hopefully none of you will see it (just kidding of course).  I don’t think any of us knew what to expect having a documentary crew here, but we’ve really enjoyed having them around.  Everyone here is so impressed at how much knowledge about the weather that they’ve picked up in a short time, and how enthusiastic they’ve been about our project.  They have also been very unobtrusive, and most of the filming has been during briefings.  It will be interesting to see the result of their hard work.  


Today we had two flights, one up to Spitsbergen, up over the ice edge to measure fluxes.  The aircraft then landed at Longyearbyen to re-fuel, before taking off again to go back over the same area at high levels to release dropsondes.  The flight crew were boasting about how good the flight was when they got back, and are going to show us some film they took with Frode’s video camera from the flight.  They flew along a glacier on Spitsbergen which apparently was spectacular.  Astrid and Frode have taken over entertainment duties for tonight and bought ice cream, to have while we watch the video.


The flight planning meeting this evening concluded with a decision to fly two flights tomorrow.  The first will go up towards Spitsbergen again, to the ice edge to have another go at getting fluxes.  The second flight will be mapping a trough/polar low depending on which model you look at.  Jon Egill and I have been looking at the latest satellite images and seen that deep convection is starting to break out in the lows south-west of Spitsbergen.  The low seems to be stronger than in the models, which is encouraging for us.  Flight planning has been adjourned until 7:30am tomorrow, because we need to look at the latest satellite images and model data or we’ll end up sending the plane to the wrong place. 


Our campaign, or ‘three-week spending spree’ as Gudmund called it (field campaigns are expensive), is nearly over.  Tomorrow will see the last flights of the campaign, and will also see the departure of much of the science crew, including myself.  Only Jon Egill, Gudmund, Øyvind and the DLR crew will stay the night, departing on Monday for their various corners of Norway and Germany.  A final update on the last flights of the campaign will be posted on Monday. 


Weather Round-up


All of the forecasts that we’ve looked at this morning (UKMO global, GFS, ECMWF, HIRLAM) show transient cyclonic features in the mslp.  None of them have anything developing though, despite the ingredients for polar low formation being present.  We have wind shear, upper-level forcing (PV anomaly), 47degC temperature difference between the surface and 500hPa and initial disturbances in the pressure field.  Looking out the window, we have shallow convection, as the cold-air outbreak is still confined to the western regions of the Norwegian seas, and hasn’t really come as far east as us yet.  In the satellite images there is no deep open cell convection organised into cloud streets associated with the cold air outbreak yet.  There is a small feature in the Norwegian sea that is visible as a comma cloud (not a particularly deep cloud) in the IR satellite images from 09UTC this morning.  This may develop and move south before decaying again, and we are monitoring this feature.


This evening’s forecasts don’t show any more development of the low pressure systems to the south-west of Spitsbergen.  However the satellite images now show deep convection breaking out.  Whether or not this will be organised and develop further we don’t know of course.  Most of the models show the low decaying, and the resulting trough moving south towards the southern Norwegian coast, with 50kt winds on the western flank.  This low/trough will be the target of the flight tomorrow.


SAP Evaluation


The SV SAPs for 12 and 24hrs optimisation have the region of maximum sensitivity within the verification region, around an area of low pressure.  For an optimisation time of 36hrs the region of maximum sensitivity is split between the southern part of the verification region and northern half, extending into the Norwegian sea. 


The ETKF SAPs for 12hrs optimisation extend north between Andøya and Svalbard, as far east as the Greenwich meridian.  The SAPs for 24 and 36hrs optimisation are similar, with the maximum in sensitivity extending another 5 degrees west.