Parameterization of cold‐season processes in the MAPS land‐surface scheme

Abstract

Abstract. A coupled atmospheric/land-surface model covering the conterminous UnitedStates with an associated 1-hour atmospheric data assimilation cycle, the Mesoscale Analysis and Prediction System (MAPS), has been improved to include a snow accumulation/melting scheme and also parameterization of processes in frozen soil. The new aspects of the land-surface model are described in this paper, along with detailed one-dimensional (l-D) tests using an 18-year observation data set from Valday, Russia. These tests show that the MAPS 1-D soil/vegetation/snow model is capable of providing accurate simulations over multiyear periods at locations with significant snow cover and frozen soil. A statistical analysis of the tests shows the expected improvement in snow depth, skin temperature, and especially in runoff from inclusion of these additional surface processes during the spring melting season. This performance in 1-D tests is a necessary prerequisite for robust long-term behavior of soil temperature and moisture fields and other components of the hydrological cycle in the 3-D MAPS coupled assimilation cycle. For GCIP a key question is the degree to which a coupled atmospheric/land-surface model, constrained by hourly assimilation of atmospheric observations to follow the evolution of the atmosphere accurately, can provide a realistic evolution of hydrological fields and time-varying soil fields that are not observed over large areas. A prerequisite for success is that the soil/vegetation/snow component of the coupled model, which is constrained only by atmospheric boundary conditions and definition of fields such as vegetation type and fraction and soil type, must be sufficiently robust to avoid drift over long periods of time. The land surface component of this model must also account for cold-season processes important in middle and 4077

Tropical cyclone predictions over the Bay of Bengal using the high‐resolution Advanced Research Weather Research and Forecasting (ARW) model

“…The modelling incorporated the following: for convection, the KF (Kain, 2004), BMJ (Betts and Miller, 1986;Janjić, 2000), GDE (Grell and Dévényi, 2002) and Grell-2 (NG: New Grell) schemes; for PBL the Yonsei University (YSU; Hong et al, 2006), MYJ (Mellor and Yamada, 1982;Janjić, 2002) and Asymmetrical Convective Model version 2 (ACM; Pleim, 2007) schemes; for cloud microphysics the LIN (Lin et al, 1983), WRF single moment 3-class (WSM3; Hong et al, 2004) and WRF Single moment 6-class (WSM6; Dudhia et al, 2008) schemes; and for surface processes the five-layer soil thermal diffusion model (SOIL; Dudhia, 1996), the NOAH land surface model (Chen and Dudhia, 2001) and rapid update cycle model (RUC; Smirnova et al, 2000). As mentioned earlier, a total of 13 simulations were conducted for each of the five TCs, with a sequential order of (i) cumulus convection, (ii) microphysics, (iii) PBL turbulence and (iv) land-surface physics, such that the best CC scheme is identified first, followed by CMP sensitivity experiments with only the best CC in order to identify the best CMP scheme; the selected CC and CMP schemes are then used for three PBL sensitivity experiments, followed by surface processes sensitivity experiments with the selected CC, CMP and PBL schemes.…”

A robust and energy-conserving model of freezing variably-saturated soil

“…Viterbo et al, 1999;Smirnova et al, 2000). For example, comparisons of results from the Project for Intercomparison of Land Surface Parameterization Schemes have shown that the models with an explicit frozen soil scheme provide more realistic soil temperature simulation during winter than those without (Luo et al, 2003).…”

Performance Evaluation of Four Different Land Surface Models in WRF

“…Special feature of RUC LSM is a thin layer spanning the ground surface that includes half of the first atmospheric layer and half of the top soil layer is used to solve the energy budgets. The heat storage in the layer is determined by contribution of soil fluxes and atmospheric fluxes (Smirnova et al, 1997). In RUC LSM, the latent heat flux is directly affected by vegetation through incorporation of free water from canopy and evapotranspiration.…”

“…The model solves heat diffusion, Richards diffusive and gravitational motions for soil moisture transfer (Richards, 1931). In the cold season phase changes of soil moisture are considered (Smirnova et al, 1997). Special feature of RUC LSM is a thin layer spanning the ground surface that includes half of the first atmospheric layer and half of the top soil layer is used to solve the energy budgets.…”

“…For this purpose, several land-surface models (LSM) have been already developed and implemented into mesoscale models (e.g. Chen and Dudhia, 2001;Smirnova et al, 1997;Pielke et al, 1997;Bringfelt, 1996;Pleim and Xiu, 1995;Giorgi et al, 1993;Bougeault et al, 1991).…”