Mesoscale covariance of transport and CO₂ fluxes: Evidence from observations and simulations using the WRF‐VPRM coupled atmosphere‐biosphere model

Abstract

[1] We developed a modeling system which combines a mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, with a diagnostic biospheric model, the Vegetation Photosynthesis and Respiration (VPRM). The WRF-VPRM modeling system was designed to realistically simulate high-resolution atmospheric CO 2 concentration fields. In the system, WRF takes into account anthropogenic and biospheric CO 2 fluxes and realistic initial and boundary conditions for CO 2 from a global model. The system uses several ''tagged'' tracers for CO 2 fields from different sources. VPRM uses meteorological fields from WRF and high-resolution satellite indices to simulate biospheric CO 2 fluxes with realistic spatiotemporal patterns. Here we present results from the application of the model for interpretation of measurements made within the CarboEurope Regional Experiment Strategy (CERES). Simulated fields of meteorological variables and CO 2 were compared against ground-based and airborne observations. In particular, the characterization by aircraft measurements turned out to be crucial for the model evaluation. The comparison revealed that the model is able to capture the main observed features in the CO 2 distribution reasonably well. The simulations showed that daytime CO 2 measurements made at coastal stations can be strongly affected by land breeze and subsequent sea breeze transport of CO 2 respired from the vegetation during the previous night, which can lead to wrong estimates when such data are used in inverse studies. The results also show that WRF-VPRM is an effective modeling tool for addressing the near-field variability of CO 2 fluxes and concentrations for observing stations around the globe.Citation: Ahmadov, R., C. Gerbig, R. Kretschmer, S. Koerner, B. Neininger, A. J. Dolman, and C. Sarrat (2007), Mesoscale covariance of transport and CO 2 fluxes: Evidence from observations and simulations using the WRF-VPRM coupled atmospherebiosphere model,

Comparing high resolution WRF-VPRM simulations and two global CO<sub>2</sub> transport models with coastal tower measurements of CO<sub>2</sub>

“…In addition the paper assesses the possibility of using hourly concentration data including nighttime in inversions by involving a mesoscale model. This work extends our previous study by Ahmadov et al (2007), which compared WRF-VPRM simulations to aircraft data for a short time period, to a much longer simulation time period and a focus on one tower site. In Sect.…”

“…This behavior is caused by phenological changes associated with the intensifying growing season. Some of the large cropland areas in the region become strong CO 2 sinks in June as shown by Ahmadov et al (2007).…”

“…A recirculation of respired nighttime CO 2 fields, for which the term "3-D rectifier effect" was established (Riley et al, 2005;Pérez-Landa et al, 2007;Ahmadov et al, 2007) is demonstrated for the case 20 May, 2005 (Fig. 5).…”

“…The WRF-VPRM model was validated against a number of meteorological and tracer observations, both ground and aircraft based (Sarrat et al, 2007;Ahmadov et al, 2007; Macatangay et al, 2008). One improvement of WRF-VPRM in the current study is the online coupling of VPRM to WRF, so that WRF produced air temperature at 2 m (T2) and shortwave downward radiation (SWDOWN) were used in VPRM to calculate CO 2 fluxes which were then provided to WRF at each integration time step.…”

“…Several mesoscale modeling systems are currently used to simulate mesoscale variations of CO 2 concentration in the atmosphere (e.g. Denning et al, 2003;van der Molen and Dolman, 2007;Sarrat et al, 2007;Ahmadov et al, 2007). In these studies mesoscale meteorological models in combination with biospheric models were used to perform forward simulations of CO 2 .…”