Measuring the impact of a new snow model using surface energy budget
process relationships
Abstract
Energy exchange at the snow-atmosphere interface in winter is important
for the evolution of temperature at the surface and within the snow,
preconditioning the snowpack for melt during spring. This study
illustrates a set of diagnostic tools that are useful for evaluating the
energy exchange at the Earth’s surface in an Earth System Model, from a
process-based perspective, using in-situ observations. In particular, a
new way to measure model improvement using the response of the surface
temperature and other surface energy budget (SEB) terms to radiative
forcing is presented. These process-oriented diagnostics also provide a
measure of the coupling strength between the incoming radiation and the
various terms in the SEB, which can be used to ensure that improvements
in predictions of user relevant properties, such as 2m temperature, are
happening for the right reasons. Correctly capturing such process
relationships is a necessary step towards achieving more skilful weather
forecasts and climate projections. These diagnostic techniques are
applied to assess the impact of a new multi-layer snow scheme in the
European Centre for Medium-Range Weather Forecasts’-Integrated Forecast
System at two high-Arctic sites (Summit, Greenland and Sodankylä,
Finland). The multi-layer scheme is expected to replace a single layer
snow scheme in the operational forecasting system, enhancing the 2m
temperature forecast reliability and skill across the northern
hemisphere in boreal winter.