High-resolution modeling in support of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE)

We describe the atmospheric modeling that underlies the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) science analysis. CARVE is an on-going, sub-orbital, multi-year (airborne field study period is 2012-2015) research mission funded by NASA whose goal is to “quantify correlations between atmospheric and surface state variables for the Alaskan terrestrial ecosystems through intensive seasonal aircraft campaigns, ground-based observations, and analysis sustained over a 5-year mission.” The regional model downscales coarser-resolution global reanalyses and provides high-resolution meteorological fields for use in an atmospheric transport model whose source-receptor (“footprint”) output fields enable carbon budget analysis studies.

Here we describe the meteorological modeling component with a focus on validation against standard atmospheric observations. The Polar variant of the Weather Research and Forecasting (WRF) model is used to drive the Stochastic Time Inverted Lagrangian Transport (STILT) model. A triply nested computational domain for WRF is chosen so that the innermost domain with 3.3-km grid spacing encompasses the entire mainland of Alaska and enables the substantial orography of the state to be represented by the underlying high-resolution topographic input field. Summary statistics of the WRF model performance on the 3.3-km grid for the calendar years 2012 to 2014 indicate good overall agreement with quality-controlled surface and radiosonde observations. Model representation of upper level variables is very good. The overall errors for the CARVE simulations are comparable to model performance metrics of similar model configurations found in the literature. The high quality of the fine-resolution WRF fields inspires confidence in their use to drive STILT for the purpose of computing footprints at commensurably increased resolution that will support accurate estimates of CO₂ and CH₄ surface-atmosphere fluxes using CARVE observations.