Long-term future projections for the Greenland and Antarctic ice sheets with the model SICOPOLIS

<p>The Coupled Model Intercomparison Project Phase 6 (CMIP6) is a major international climate modelling initiative. As part of it, the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) was devised to assess the likely sea-level-rise contribution from the Greenland and Antarctic ice sheets until the year 2100. This was achieved by defining a set of future climate scenarios by evaluating results of CMIP5 and CMIP6 global climate models (GCMs, including MIROC) over and surrounding the Greenland and Antarctic ice sheets. These scenarios were used as forcings for a variety of ice-sheet models operated by different working groups worldwide (Goelzer et al. 2020, doi: 10.5194/tc-14-3071-2020; Seroussi et al. 2020, doi: 10.5194/tc-14-3033-2020).</p><p>Here, we use the model SICOPOLIS to carry out extended versions of the ISMIP6 future climate experiments for the Greenland and Antarctic ice sheets until the year 3000. For the atmospheric forcing (anomalies of surface mass balance and temperature) beyond 2100, we sample randomly the ten-year interval 2091-2100, while the oceanic forcing beyond 2100 is kept fixed at 2100 conditions. We conduct experiments for the pessimistic, "business as usual" pathway RCP8.5 (CMIP5) / SSP5-8.5 (CMIP6), and for the optimistic RCP2.6 (CMIP5) / SSP1-2.6 (CMIP6) pathway that represents substantial emissions reductions. For the unforced, constant-climate control runs, both ice sheets are stable until the year 3000. For RCP8.5/SSP5-8.5, they suffer massive mass losses: For Greenland, ~1.7 m SLE (sea-level equivalent) for the 12-experiment mean, and ~3.5 m SLE for the most sensitive experiment. For Antarctica, ~3.3 m SLE for the 14-experiment mean, and ~5.3 m SLE for the most sensitive experiment. For RCP2.6/SSP1-2.6, the mass losses are limited to a two-experiment mean of ~0.26 m SLE for Greenland, and a three-experiment mean of ~0.25 m SLE for Antarctica. Climate-change mitigation during the next decades will therefore be an efficient means for limiting the contribution of the ice sheets to sea-level rise in the long term.</p>

The Comparison Study of Targeting Observation for Extratropical Transition of Hurricane Fabian

This study compares the propagation methods of the impact of targeted observations during the extratropical transition (ET) of Hurricane Fabian in three denial experiments. In sensitive experiment, the signal (forecast difference between denial experiments and control) propagates from the tropical cyclone (TC) to the midlatitude jet through the interaction between the TC and the jet itself. Thereafter, signals propagate eastward along the jet by way of Rossby wave packets. Some differences exist between random/Atlantic and sensitive experiment although many of their signal propagation characteristics are similar. The signal in random experiment is the weakest, and that in Atlantic experiment is the strongest. In Atlantic experiment, initial signals appear not only in Fabian, but also in other regions. In some cases, signals even do not appear in Fabian. Its propagation method is similar to that in sensitive and random experiment except some signals exist at ridges occasionally. From the discussion above, we conclude that targeted observations have more positive impact than random observations, but can not replace observations taken in the whole Atlantic.

Using Cluster Analysis to Improve Marketing Experiments

When the selection of a sample of stores or cities requires a high degree of similarity among the test units in order to ensure a sensitive experiment, the sample may no longer represent the market. These conflicting requirements can be satisfied by choosing the sample from clusters displayed in a reduced space representation of the market.

Experiments on Maize and Groundnut using Micro-Plots

SUMMARYThe results are presented of an investigation into the use of very small plots for experimental work on maize (Zea mays) and groundnut (Arachis hypogaea), for the first three harvests of a project which is continuing. Despite the diminutive plot size, the random variation was quite low, resulting in a fairly sensitive experiment. The yield responses to increasing plant density were pronounced for both maize and groundnut, giving optimal spacings of 30 × 6 in. and 12 × 4 in. respectively.