Investigating the effect of seasonal plant growth and development in three-dimensional atmospheric simulations. Part II: Atmospheric response to cropgrowth and development

The authors examine the effect of seasonal crop development and growth on t he atmospheric boundary layer in the warm season over the central Great Pla ins region of North America. They introduced daily crop development and gro wth functions into the Biosphere- Atmosphere Transfer Scheme (BATS) coupled to the National Center for Atmospheric Research Regional Climate Model ver sion 2 (NCAR RegCM2). Coupled RegCM/ BATS simulations were performed over t he conterminous United States for a dry (1988) and favorably moist (1991) g rowing seasons at a spatial resolution of 90 km x 90 km. Largest difference s between the control and interactive runs occurred in 1988, when up to 45% differences in surface latent and sensible heat fluxes were simulated in r esponse to different Leaf Area Index (LAI) parameterizations employed by th e models (in June and July, LAI was about 5 in the control cases and betwee n 1 and 2 in the interactive cases). Two to four degreesC differences in ai r temperatures resulted in response to such changes in surface fluxes. Mixi ng ratio, lower atmospheric winds, and precipitation were also affected. Th ese effects had a distinct diurnal pattern with the largest differences see n in midafternoon hours and smallest differences seen at night. The differe nces between the control and interactive simulations were largest near the surface and dampened with height. The boundary layer stratification (i. e., vertical profiles of equivalent potential temperature) produced with inter active runs was more stable compared to the control runs. Anemometer height maximum daily temperature and precipitation simulated in the interactive r uns agreed better with observations compared to those of the control runs.