Abstract
espanolUna gran variedad de formas de calcular el transporte radiativo da lugar a parametrizaciones varias. Las diferencias entre ellas implican resultados distintos para los flujos radiativos, incluso en las mismas condiciones atmosfericas. Dado que el transporte de la radiacion solar y de la radiacion terrestre respresenta el proceso fisico primordial que da forma a la circulacion atmosferica, les diferencias mencionadas deben tener un impacto en la calidad de los modelos de prediccion numerica del tiempo. En este trabajo se presenta un analisis del papel de las parametrizaciones de transporte de radiacion de onda corta en el modelo Weather Research and Forecasting (WRF-ARW). El estudio compara el efecto de cuatro esquemas (Dudhia, New Goddard, CAM y RRTMG) en dos casos para un dominio de integracion centrado en Cataluna: i) sin nubes, ii) con cielo cubierto. Se analizan los procesos de realimentacion directos e indirectos entre los aspectos dinamicos y las parametrizaciones fisicas debidos a los cambios en el calculo de la ecuacion de transporte radiativo. Los efectos acumulados de estas variaciones se estudian mediante tres ventanas temporales: el inicio de la simulacion (0-23 h), el dia siguiente (24-47 h) y el tercer dia (48-71 h). Estos analisis se focalizan en algunos campos especificos del modelo numerico; desde los campos mas directamente relacionados con los esquemas de radiacion de onda corta, como la irradiancia horizontal global o los perfiles la velocidad de calentamiento, a los campos aparentemente afectados de forma secundaria, como la velocidad del viento o la composicion de las nubes, entre otros. Las diferencias observadas entre las integraciones usando distintas parametrizaciones aumentan con el horizonte de la simulacion, siendo mas importantes en el escenario de cielo cubierto que en el de sin nubes. EnglishA wide range of approaches for radiative transfer computations leads to several parameterizations. Differences in these approximations bring about distinct results for the radiative fluxes, even under the same atmospheric conditions. Since the transfer of solar and terrestrial radiation represents the primordial physical process that shapes the atmospheric circulation, these deviations must have an impact on the numerical weather prediction (NWP) model performance. In this paper, an analysis of the role of shortwave schemes on the Weather Research and Forecasting (WRF-ARW) model is presented. The study compares the effect of four parameterizations (Dudhia, New Goddard, CAM and RRTMG) in two cases: i) cloudless and ii) cloudy sky situations for a domain defined over Catalonia (northeast of the Iberian Peninsula). We analyze the direct and the indirect feedback between the dynamical aspects and the physical parameterizations driven by changes in the radiative transfer equation computation. The cumulative effect of these variations are studied through three simulation windows: current day (0-23 h), day-ahead (24-47 h) and two days ahead (48-71 h). These analyses are focused on several NWP model fields. From the most directly related to shortwave schemes such as global horizontal irradiance or the heating rate profile, to apparently secondary outcomes such as wind speed or cloud composition among others. The differences observed between model runs using different solar parameterizations increase with the simulation horizon, being more important in the cloudy scenario than in the cloudless sky.
Highlights
IntroductionSince the transfer of terrestrial and solar radiation represents the primordial physical process that shapes the atmospheric circulation, an understanding of numerical weather prediction (NWP) model performance requires a detailed understanding of the interaction of these processes with the other mechanisms represented by the model
Since the transfer of terrestrial and solar radiation represents the primordial physical process that shapes the atmospheric circulation, an understanding of numerical weather prediction (NWP) model performance requires a detailed understanding of the interaction of these processes with the other mechanisms represented by the model.For most of the weather applications, some modeling elements such as cloud physics, convection or initial and boundary conditions, among others, have a high impact, leaving solar radiation in second place
This paper offers a discussion about the impact and the role of the shortwave parameterizations in mesoscale simulations comparing four available schemes in version 3.5 of the WRF-ARW model: Dudhia, New Goddard, NCAR Community Atmosphere Model (CAM) and Rapid Radiative Transfer Model for GCMs (RRTMG)
Summary
Since the transfer of terrestrial and solar radiation represents the primordial physical process that shapes the atmospheric circulation, an understanding of numerical weather prediction (NWP) model performance requires a detailed understanding of the interaction of these processes with the other mechanisms represented by the model. For most of the weather applications, some modeling elements such as cloud physics, convection or initial and boundary conditions, among others, have a high impact, leaving solar radiation in second place. In renewable solar energy to model the resource for forecasting as well as for prospecting applications. A simple, fast and accurate computation of the radiative transfer equation (RTE) becomes an important challenge in NWP models. From a computational point of view, since the RTE in plane-parallel atmospheres involves integrals over the entire spectrum, 2015 Author(s).
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