A new moisture tagging capability in the Weather Research and Forecasting Model: formulation, validation and application to the 2014 Great Lake-effect snowstorm

Abstract

Abstract.A new moisture-tagging tool, usually known as water vapor tracer (WVT) method or online Eulerian method, has been implemented into the Weather Research and Forecasting (WRF) regional meteorological model, enabling it for precise studies on atmospheric moisture sources and pathways. We present here the method and its formulation, along with details of the implementation into WRF. We perform an in-depth validation with monthly long simulations over North America at 20km resolution, tagging all possible moisture sources: lateral boundaries, continental, maritime or lake surfaces and initial 5 atmospheric conditions. We estimate errors as the moisture or precipitation amounts that cannot be traced back to any source.Validation results indicate that the method exhibits high precision, with errors considerably lower than 1% during the entire simulation period, for both precipitation and total precipitable water. We apply the method to the Great Lake-effect snowstorm of November 2014, aiming at quantifying the contribution of lake evaporation to the large snow accumulations observed in the event. We perform simulations in a nested domain at 5km resolution with the tagging technique, demonstrating that about 10 30-50% of precipitation in the regions immediately downwind, originated from evaporated moisture in the Great Lakes. This contribution increases to between 50-60% of the snow water equivalent in the most severely affected areas, which suggests that evaporative fluxes from the lakes have a fundamental role in producing the most extreme accumulations in these episodes, resulting in the highest socio-economic impacts.

Contribution of atmospheric moisture transport to winter Arctic warming

“…In addition, Arctic atmospheric moisture has multiple sources, which further complicates the calculation. Although a number of tracking methods, such as isotopic methods (Rogers et al ., ; Groves and Francis, ; ), box models (Gimeno et al ., ), offline Lagrangian particle dispersion models (Vazquez et al ., ; Gimeno‐Sotelo et al ., ), and numerical water vapour tracers (Eiras‐Barca et al ., ; Insua‐Costa and Miguez‐Macho, ), have been applied to examine the amount of intruding moisture, further calculation of its warming effect is still difficult. As aforementioned, the intruding moisture will undergo complicated physical processes; therefore, full consideration of the impact of each process on SAT is almost impossible.…”

Simultaneous Episodes of Heavy Rainfall in Morocco and Southern Alps: 1. Mesoscale Simulations and Episode Climatology (1979–2016)

“…The latter is a key 3‐D variable, needed for the evaluation. In addition, differently from the alternative more recent Eulerian approaches (Insua‐Costa & Miguez‐Macho, ), the modeled evaporation sources can be distributed in detailed map sequences together with the target vapor, without the need of using prescribed areas (sea‐land‐air boundaries), used in Eulerian models, which will always show a uniform distribution of vapor sources inside the prescriptions.…”

A Joint Soil‐Vegetation‐Atmospheric Water Tagging Procedure With WRF‐Hydro: Implementation and Application to the Case of Precipitation Partitioning in the Upper Danube River Basin

“…The atmospheric branch of the hydrological cycle simulated by a climate model can be examined with a surface evaporation tagging method, which consists in tracking the evaporated water online, that is throughout the model run, from a source region until it precipitates or is advected outside of the simulation domain (Arnault, Knoche, et al, ; Dominguez et al, ; Insua‐Costa & Miguez‐Macho, ; Knoche & Kunstmann, ; Sodemann et al, ; Wei et al, , ). It is noted that Arnault, Knoche, et al () and Dominguez et al () and Insua‐Costa and Miguez‐Macho's () tagging methods were independently developed in the WRF model. The surface evaporation tagging method allows to quantify regional precipitation recycling, which is the relative amount of local precipitation originating from local surface evaporation in a region.…”