Dear ISIMIP community,
we'd like to give you a few updates on the progress of the preparations for ISIMIP3, as well as the extension of ISIMIP2a.
We have been preparing the input data and protocol for an extension of the ISIMIP2a simulation phase, including climate forcing datasets that cover the most recent years (e.g. WFDEI until 2016, new ERA5 until 2018). We are also extending the associated land-use data. The last missing piece is a counterfactual climate forcing dataset that represents an alternative historical world without the anthropogenic climate change trend but with all the observed variability. This will be useful for attribution studies of past impacts. We are currently finalizing the methodology for this dataset. Once we have it ready, we will publish the ISIMIP2a-extended simulation protocol together with all the necessary input data - stay tuned.
At the same time, we are busy preparing for ISIMIP3. Like ISIMIP2, ISIMIP3 will have two complementary parts: ISIMIP3b will provide up-to-date impact projections under future climate change, while ISIMIP3a will serve to evaluate the impact models using historical observations. (Of course this is only the most general idea behind the simulation set-up, which will hopefully serve all kinds of interesting analyses).
ISIMIP3b will be using CMIP6 climate simulations as input. We are striving to prepare the input data and protocol for ISIMIP3b as soon as possible, so that at least some simulations can be completed, and papers can be written, in time for the IPCC AR6 WG2 submission deadline (1st July 2020). We have already developed an improved bias-adjustment methodology (see paper by Stefan Lange, https://www.geosci-model-dev.net/12/3055/2019/). The observational dataset to be used as target for bias adjustment is currently being developed in collaboration with ECMWF. At the same time, we are monitoring the upload of CMIP6 data by the climate modeling groups. Currently there are four climate models providing all necessary variables, but we hope this number will rise over the next few weeks. We will then make a selection from the available models based on the dicusssions during the Paris Workshop. As soon as the target dataset and the climate model data are available, we will do the bias adjustment, and then publish the ISIMIP3b protocol together with the forcing data.
We are excited about these new developments, and hope that you bear with us even if things take a bit longer than planned. We will keep you informed. In the meantime, don't hesitate to contact us if you have any questions or suggestions.
Best regards from Potsdam,
the ISIMIP team at PIK