Land-Use Improvements in the Weather Research and Forecasting Model over Complex Mountainous Terrain and Comparison of Different Grid Sizes

Alessio Golzio,Manuela Pelfini,Claudio Cassardo,Silvia Ferrarese,Gugliemina Adele Diolaiuti

doi:10.1007/s10546-021-00617-1

Abstract

Weather forecasts over mountainous terrain are challenging due to the complex topography that is necessarily smoothed by actual local-area models. As complex mountainous territories represent 20% of the Earth’s surface, accurate forecasts and the numerical resolution of the interaction between the surface and the atmospheric boundary layer are crucial. We present an assessment of the Weather Research and Forecasting model with two different grid spacings (1 km and 0.5 km), using two topography datasets (NASA Shuttle Radar Topography Mission and Global Multi-resolution Terrain Elevation Data 2010, digital elevation models) and four land-cover-description datasets (Corine Land Cover, U.S. Geological Survey land-use, MODIS30 and MODIS15, Moderate Resolution Imaging Spectroradiometer land-use). We investigate the Ortles Cevadale region in the Rhaetian Alps (central Italian Alps), focusing on the upper Forni Glacier proglacial area, where a micrometeorological station operated from 28 August to 11 September 2017. The simulation outputs are compared with observations at this micrometeorological station and four other weather stations distributed around the Forni Glacier with respect to the latent heat, sensible heat and ground heat fluxes, mixing-layer height, soil moisture, 2-m air temperature, and 10-m wind speed. The different model runs make it possible to isolate the contributions of land use, topography, grid spacing, and boundary-layer parametrizations. Among the considered factors, land use proves to have the most significant impact on results.

Highlights

The lowest part of the atmosphere – the planetary boundary layer (PBL) and, closer to the land surface, the surface layer – is the region where the exchanges of energy and mass between surface and atmosphere take place (Stull 1988)
We present an assessment of the Weather Research and Forecasting model with two different grid spacings (1 km and 0.5 km), using two topography datasets (NASA Shuttle Radar Topography Mission and Global Multi-resolution Terrain Elevation Data 2010, digital elevation models) and four land-cover-description datasets (Corine Land Cover, U.S Geological Survey landuse, MODIS30 and MODIS15, Moderate Resolution Imaging Spectroradiometer land-use)
The first improvement concerns the major accuracy of the topography by using the updated digital elevation models (DEMs) (NASA Shuttle Radar Topography Mission (SRTM)) with respect to the default (GMTED2010)

Summary

Introduction

The lowest part of the atmosphere – the planetary boundary layer (PBL) and, closer to the land surface, the surface layer – is the region where the exchanges of energy and mass between surface and atmosphere take place (Stull 1988). The interactions between the atmosphere, the cryospheric portion of the hydrosphere, the biosphere, lithosphere, and anthroposphere are especially of interest in high mountain environments, where landscape modifications are increasing under ongoing climatic change (Carlson et al 2014; Carrivick et al 2018), and where weather-related hazards and risks are greater (Pelfini et al 2009; Zanoner et al 2017). Exposure to meteorological and geomorphic events can lead to changes in risk scenarios (IPCC 2014). In this fragile environment, accurate forecasts that capture the strength of interactions between the surface and the boundary layer are crucial

Methods

Results

Conclusion