For those not in the know, JULES stands for the Joint UK Land Environment Simulator and is a community land surface model that evolved from the Met Office Surface Exchange Scheme. It can either be coupled to the Met Office Unified Model (UM) and used as its land surface component, or run off-line as a stand-alone land surface model. For full details, see https://jules.jchmr.org/.
The meeting, running this year from 28-29 June 2016 at the Lancaster Environment Centre (LEC), is an annual event designed to bring together the JULES community, to discuss the latest upgrades, simulations and ongoing work using the model. There was then a training course immediately afterwards, from 29-30 June also at Lancaster, for those just starting to use the model and for anyone wanting to know more.
Tuesday 28 June
The meeting began around 10:30 AM to allow people to arrive, but we had driven up the day before (which, following a 6 hour drive, was a good thing) so we were able to have a fairly leisurely start, putting up my poster (see below) before the first round of talks. The first session was an introduction to JULES, as well as an interesting outline of the various updates since the last meeting. In short, in the last year we have moved from version 4.3 to 4.6, with apparently the latest upgrade to 4.6 being a major one and containing over 40 science additions and numerous technical changes and bug fixes. We then had a couple of interesting talks on how JULES fits into the various model inter-comparison projects (MIPs), which are now being formed in time for the next IPCC report, as well as a discussion of some of the assessment and benchmarking tools used by the Met Office and others for various MIPs (e.g. iLAMB).
After lunch, the focus moved to vegetation and disturbance, with a number of talks on using JULES to look at biophysical homeostasis of leaf temperature, disturbance and mortality in global vegetation, and forest thinning. There was also a very interesting talk of the incorporation of INFERNO into JULES, an interactive fire and emissions scheme. The 3rd session, after coffee, focused on crops and ecosystems within JULES, but I admit I ducked out of this session as I had some urgent work that needed doing. Unfortunately, although it would be nice to attend every talk, when you are working on multiple projects simultaneously, a whole day away from the computer is a big mistake.
I rejoined the group around 5 PM, just in time for the poster session in the LEC Courtyard (which was fortunately covered, as it was monsoon-like (only without the heat) outside. Around 20 posters were presented, including mine which can be seen below and downloaded at http://goo.gl/M322ab.
In my poster, which focused on the ability of JULES to simulate African river discharge under both present-day and mid Holocene (~ 6k years ago) conditions, I firstly ran JULES (version 4.3) twice, both for 30 years over Africa but with different rainfall datasets as input data. The results suggested a general insensitivity to the forcing data. I then ran the model again, this time with river routing turned on, under present-day conditions, comparing simulated river discharge with observations from the GRDC network. The results suggested that the model was able to reproduce the seasonal cycle of river discharge for selected African rivers, but did less well in terms of magnitudes. Lastly, I ran the model once more, but with the input rainfall forcing data modified slightly to represent mid-Holocene conditions (essentially an exaggerated seasonal cycle, with increased rainfall during the wet season and a drier dry season). Initial results suggested a slight increase in the seasonal cycle of river discharge for selected rivers under mid-Holocene conditions, relative to the present-day.
The day concluded with a conference dinner held on the other side of campus.
Wednesday 29 June
The morning session focused on soil and urban processes within JULES, including the impact of carbon, but again I ducked out of this session as I had several things that required my full attention. I rejoined the group later on that morning, to listen to several interesting talks on other applications of JULES - of particular interest to me was a talk on using JULES to investigate drought probabilities over East Africa, and another talk on using the model to look at the current and future water balance over West Africa. This session concluded with a short discussion of practicalities: the date and venue for the next meeting, the committee, and planned updates over the forthcoming year.
After the official end to the meeting, and after lunch, the training course began. This was held in a computer lab in the Management School, and the afternoon session consisted of a number of short talks (also broadcast live, as a webinar) to introduce JULES: what it is, installation and running instructions, how to interpret output, etc. We were then given a worksheet with a number of tasks, and left to get on with the exercises whilst the demonstrators circulated and gave advice. Although the talks and exercises were interesting, I will admit that (and this is not a negative reflection on the course demonstrators) it was nothing I hadn't already done, many times before. This was entirely my own fault and, in retrospect, perhaps I should not have attended the course. I registered for it soon after Christmas, because I only began using JULES in November and therefore thought it was worthwhile to attend a training course. However, over the months in between, I used the model a great deal in a number of different configurations - undoubtedly helped by my 10 years experience of using the UM, which is significantly more complex - so things like FCM were already second-nature to me. Nevertheless, despite having done many of the exercises before, the afternoon was interesting.
Thursday 30 June
The rest of the training course was simply an extension of the previous afternoon, giving us all more time to work through the exercises and ask any questions. Perhaps a little selfishly, I latched onto this latter aspect, and brought up a reasonably high-level problem that I have been experiencing over the last few months; namely, my inability to run JULES in regional mode (over Africa) when using river routing. Globally it was fine, but when running regionally it was generating a highly cryptic error which I could not resolve. Fortunately, however, after much discussion and fiddling by several of the demonstrators, they fixed this problem. So a very useful morning.
All in all, therefore, I enjoyed the science meeting and the training course afterwards, and the whole event was thought-provoking with some very interesting talks and discussions afterwards. I just want to finish by saying a big thank you to all those who organised the event, and to all the demonstrators who ran the training course. Much appreciated.
