THE PROJECT FOR INTERCOMPARISON OF LAND-SURFACE PARAMETERIZATION SCHEMES (PILPS) - PHASE-2 AND PHASE-3

The World Climate Research Programme Project for Intercomparison of La nd Surface Parameterization Schemes (PILPS) is moving into its second and third phases that will exploit observational data and consider the performance of land surface schemes when coupled to their host climat e models. The first stage of phase 2 will focus on an attempt to under stand the large differences found during phase 1. The first site from which observations will be drawn for phase 2 intercomparisons is Cabau w, the Netherlands (51 degrees 58'N, 4 degrees 56'5), selected specifi cally to try to reduce one of the causes of the divergence among the p hase 1 results: the initialization of the deep soil moisture. Cabauw's deep soil is saturated throughout the year. it also offers a quality controlled set of meteorological forcing and 160 days of flux measurem ents. PILPS phase 2 follows the form of the phase 1 intercomparisons: simple off-line integrations and comparisons, but in phase 2 participa ting schemes' results will be compared against observed fluxes. Prelim inary results indicate that between model variability persists (i) in better specified experiments and (ii) in comparison with data. Althoug h median values are consistent with observations,there is a large rang e among models. Phase 3, in which the intercomparison of PILPS schemes as a component of global atmospheric circulation models, is being con ducted jointly with the Atmospheric Model Intercomparison Project (AMI P) as diagnostic subproject number 12. Preliminary results suggest tha t results differ by about the same range as in the off-line experiment s in phases 1 and 2. Incomplete diagnostics suggest that bucket and ca nopy models differ and that variability among models can be tracked to the soil moisture parameterization. This paper offers a review of the PI LPS project to date and an invitation to participate in PILPS' cur rent and future activities.