The World Climate Research Programme (WCRP) Project for Intercomparison of Land- surface Parameterisation Schemes (PILPS) is a joint activity sponsored by the Global Energy and Water Cycle Experiment (GEWEX) and the Working Group on Numerical Experimentation (WGNE). PILPS has been operational since 1992 with the objective of improving the prediction of Global Climate Models (GCMs) and Numerical Weather Prediction (NWP) models through increased understanding of land-surface-atmosphere interactions parameterised in Land Surface Schemes (LSSs). This paper presents an update on the past present and future status of PILPS activities.
PILPS consist of five phases. Phase 0 is an on-going documentation stage which consists of the experimental design and instructions for Phases 1 and 2 of PILPS and references for all participating LSSs. Phases 1 and 2 are comprised of a suite of experiments, where LSSs are run in an off-line mode (ie. not coupled to their host atmospheric model) and are forced with, and validated against, synthetic (Phase 1) and observational (Phase 2) data. Phase 3 of PILPS is contained within the Atmospheric Model Intercomparison Project (AMIP) Diagnostic Subproject No. 12 and has been developed to assess the performance of LSSs coupled to their host AGCM. In Phase 4 several LSSs are coupled to the same AGCM (Phase 4a) and NWP model (Phase 4b) to detail land-atmosphere interactions in numerical simulations. Phase 4c investigates the development of a generic land surface-atmospheric host model interface.
PILPS is an integral part of the land-surface modelling community with 41 LSSs participating in PILPS in various ways. The philosophy behind PILPS is to provide a platform where all land surface modellers can benefit from mutual interaction, increased communication and a testbed from which their own LSSs may be validated, leading to model improvements. PILPS is also a self-evolving project. Each Phase of PILPS has tried to investigate different aspects of land-surface parameterisations, whilst building on past experiences and encourages participation with respect to existing and proposed experimental designs.
A brief overview of all phases of PILPS will be presented, major findings and future plans including further off-line intercomparisons and increased participation in coupled experiments