Advancement toward coupling of the VAMPER permafrost model within the Earth system model <I>i</I>LOVECLIM (version 1.0): description and validation

Abstract

Abstract. The VU Amsterdam Permafrost (VAMPER) permafrost model has been enhanced with snow thickness and active layer calculations in preparation for coupling within the iLOVECLIM Earth system model of intermediate complexity (EMIC). In addition, maps of basal heat flux and lithology were developed within ECBilt, the atmosphere component of iLOVECLIM, so that VAMPER may use spatially varying parameters of geothermal heat flux and porosity values. The enhanced VAMPER model is validated by comparing the simulated modern-day extent of permafrost thickness with observations. To perform the simulations, the VAMPER model is forced by iLOVECLIM land surface temperatures. Results show that the simulation which did not include the snow cover option overestimated the present permafrost extent. However, when the snow component is included, the simulated permafrost extent is reduced too much. In analyzing simulated permafrost depths, it was found that most of the modeled thickness values and subsurface temperatures fall within a reasonable range of the corresponding observed values. Discrepancies between simulated and observed permafrost depth distribution are due to lack of captured effects from features such as topography and organic soil layers. In addition, some discrepancy is also due to disequilibrium with the current climate, meaning that some observed permafrost is a result of colder states and therefore cannot be reproduced accurately with constant iLOVECLIM preindustrial forcings.

LGM Permafrost Thickness and Extent in the Northern Hemisphere derived from the Earth System Model iLOVECLIM

“…() refers to as the Last Permafrost Maximum (LPM). Following this research, it is the aim of our present work to provide new estimates of both the LGM permafrost extent and thickness using the VU University Amsterdam Permafrost Snow (VAMPERS) model (Kitover et al ., , ), forced by air temperatures and snow thickness from ECBilt, the atmosphere‐land component within i LOVECLIM (Roche, ; Goosse et al ., ). Specifically, we aim to answer the following research questions: (1) What is the model‐based extent and thickness distribution during the LGM; and (2) How well can this simulation be done using a one‐dimensional (1D) permafrost model, forced using a relatively simple Earth system model?…”

Reply to Referee #2 (J. Fyke)

“…2.1 The iLOVECLIM model iLOVECLIM (here in version 1.1) is a fork of the LOVE-CLIM 1.2 model code, extensively described in Goosse et al (2010). Whilst the physics in the atmosphere, ocean and land surface has remained mostly unchanged, the major bifurcations from Goosse et al (2010) consist of the addition of a water oxygen isotope cycle (Roche, 2013;Roche and Caley, 2013), an oceanic carbon model (Bouttes et al, 2015), an alternative ice sheet model (Roche et al, 2014), the reimplementation of the initial iceberg model (Bügelmayer et al, 2015) and a permafrost model (Kitover et al, 2015). The LOVECLIM family of models contain a free surface ocean general circulation model with an approximately 3 • spatial resolution and 20 vertical layers.…”

“…Alternatively, Robinson et al (2010) embed a simplified regional energymoisture balance model in an EMIC in order to assess subgrid processes unresolved by their native atmospheric model. Although statistical downscaling has been applied to EMIC outputs (Vrac et al, 2007;Levavasseur et al, 2011), these techniques were not used to couple the various different components of models.…”

Online dynamical downscaling of temperature and precipitation within the <i>i</i>LOVECLIM model (version 1.1)

“…Whilst the physics in the atmosphere, ocean and land surface has remained mostly unchanged, the major bifurcations from Goosse et al (2010) consist of the addition of a water oxygen isotope cycle (Roche, 2013;Roche and Caley, 2013), an oceanic carbon model (Bouttes et al, 2015), an alternative ice sheet model (Roche et al, 2014), the reimplementation of the initial iceberg model (Bügelmayer et al, 2015) and a permafrost model (Kitover et al, 2015). The LOVECLIM family of models contain a free surface ocean general circulation model with an approximately 3 • spatial resolution and 20 vertical layers.…”