Validation Study of the CAPS Model Land Surface Scheme Using the 1987 Cabauw/PILPS Dataset

Chang, Sam; Hahn, D.; Yang, Chuanguo; Norquist, Donald C.; Ek, Michael

doi:10.1175/1520-0450(1999)038<0405:vsotcm>2.0.co;2

Cited by 31 publications

(23 citation statements)

References 32 publications

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“…Key variables in the SEB, such as heat and water vapor fluxes, are influenced by PBL concentrations of these quantities, which themselves are influenced by their surface fluxes, forming a negative feedback loop (McNaughton and Raupach 1996). We attempt to incorporate these important feedbacks in the study, by coupling our 3D, time-dependent LES code (Sullivan et al 1996) to the National Centers for Environmental Prediction/Oregon State University/ Air Force/Office of Hydrology (NOAH) LSM, version 2.0 (Chang et al 1999).…”

Section: Land-atmosphere Couplingmentioning

confidence: 99%

“…For nonprecipitating nonfreezing environments, the SEB for an infinitesimally thin layer at the ground surface can be written (following Brutsaert 1982;Chang et al 1999) as R n ϭ H ϩ LE ϩ G, where R n is the net radiation, H is the sensible heat flux, LE is the latent heat flux, and G is the soil heat flux. The radiation components are taken as positive toward the surface and all other components are considered positive away from the surface.…”

Section: Land-atmosphere Couplingmentioning

confidence: 99%

“…At the lower boundary of the LSM, the hydraulic diffusivity is assumed to be zero so that the soil water flux is determined solely by gravitational conduction and the soil heat flux is computed from a vertical temperature gradient between the lowest LSM model level and a specified soil temperature at an imaginary grid point one meter below the bottom of the model. Further details can be found in Mahrt and Pan (1984), Pan and Mahrt (1987), and Chang et al (1999). To improve scalability when solving the LSM for the coupled surface boundary condition, we use MPI to break up the calculation in the x direction.…”

Section: Appendixmentioning

confidence: 99%

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The Influence of Idealized Heterogeneity on Wet and Dry Planetary Boundary Layers Coupled to the Land Surface

Patton

Sullivan

Moeng

2005

Journal of the Atmospheric Sciences

229

303

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This manuscript describes numerical experiments investigating the influence of 2-30-km striplike heterogeneity on wet and dry convective boundary layers coupled to the land surface. The striplike heterogeneity is shown to dramatically alter the structure of the convective boundary layer by inducing significant organized circulations that modify turbulent statistics. The impact, strength, and extent of the organized motions depend critically on the scale of the heterogeneity relative to the boundary layer height z i . The coupling with the land surface modifies the surface fluxes and hence the circulations resulting in some differences compared to previous studies using fixed surface forcing. Because of the coupling, surface fluxes in the middle of the patches are small compared to the patch edges. At large heterogeneity scales (/z i ϳ18) horizontal surface-flux gradients within each patch are strong enough to counter the surface-flux gradients between wet and dry patches allowing the formation of small cells within the patch coexisting with the large-scale patch-induced circulations. The strongest patch-induced motions occur in cases with 4 Ͻ /z i Ͻ 9 because of strong horizontal pressure gradients across the wet and dry patches. Total boundary layer turbulence kinetic energy increases significantly for surface heterogeneity at scales between /z i ϭ 4 and 9; however, entrainment rates for all cases are largely unaffected by the striplike heterogeneity.Velocity and scalar fields respond differently to variations of heterogeneity scale. The patch-induced motions have little influence on total vertical scalar flux, but the relative contribution to the flux from organized motions compared to background turbulence varies with heterogeneity scale. Patch-induced motions are shown to dramatically impact point measurements in a free-convective boundary layer. The magnitude and sign of this impact depends on the location of the measurement within the region of heterogeneity.

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Section: Land-atmosphere Couplingmentioning

confidence: 99%

Section: Land-atmosphere Couplingmentioning

confidence: 99%

Section: Appendixmentioning

confidence: 99%

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The Influence of Idealized Heterogeneity on Wet and Dry Planetary Boundary Layers Coupled to the Land Surface

Patton

Sullivan

Moeng

2005

Journal of the Atmospheric Sciences

229

303

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“…The RCM used in this study is composed of the Mesoscale Atmospheric Simulation (MAS) model (Soong and Kim 1996;Kim 2005;Kim et al 2006) interactively coupled with the NCEP-Oregon State University-Air Force-Office of Hydrology (NOAH) land surface scheme (Kim and Ek 1995;Chang et al 1999). The MAS model is a primitive-equation, limited-area atmospheric model written on the σ-coordinates.…”

Section: Model Descriptionmentioning

confidence: 99%

Direct and semi-direct radiative effects of anthropogenic aerosols in the Western United States: Seasonal and geographical variations according to regional climate characteristics

Kim

Liou

et al. 2011

Climatic Change

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The direct and semi-direct radiative effects of anthropogenic aerosols on the radiative transfer and cloud fields in the Western United States (WUS) according to seasonal aerosol optical depth (AOD) and regional climate are examined using a regional climate model (RCM) in conjunction with the aerosol fields from a GEOS-Chem chemicaltransport model (CTM) simulation. The two radiative effects cannot be separated within the experimental design in this study, thus the combined direct-and semi-direct effects are called radiative effects hereafter. The CTM shows that the AOD associated with the anthropogenic aerosols is chiefly due to sulfates with minor contributions from black carbon (BC) and that the AOD of the anthropogenic aerosol varies according to local emissions and the seasonal low-level winds. The RCM-simulated anthropogenic aerosol radiative effects vary according to the characteristics of regional climate, in addition to the AOD. The effects on the top of the atmosphere (TOA) outgoing shortwave radiation (OSRT) range from −0.2 Wm −2 to −1 Wm −2 . In Northwestern US (NWUS), the maximum and minimum impact of anthropogenic aerosols on OSRT occurs in summer and winter, respectively, following the seasonal AOD. In Arizona-New Mexico (AZNM), the effect of anthropogenic sulfates on OSRT shows a bimodal distribution with winter/summer minima and spring/fall maxima, while the effect of anthropogenic BC shows a single peak in summer. The anthropogenic aerosols affect surface insolation range from −0.6 Wm −2 to −2.4 Wm −2 , with similar variations found for the effects on OSRT except that the radiative effects of anthropogenic BC over AZNM show a bimodal distribution with spring/fall maxima and summer/winter minima. The radiative effects of anthropogenic sulfates on TOA outgoing longwave radiation (OLR) and the surface downward longwave radiation (DLRS) are notable only in summer and are characterized by strong geographical contrasts; the summer OLR in NWUS (AZNM) is reduced (enhanced) by 0.52 Wm −2 (1.14 Wm −2 ). The anthropogenic sulfates enhance (reduce) summer DLRS by 0.2 Wm −2 (0.65 Wm −2 ) in NWUS (AZNM). The anthropogenic BC affect DLRS noticeably only in AZNM during summer. The anthropogenic aerosols affect the cloud water path (CWP) and the radiative transfer noticeably only in summer when convective clouds are dominant. Primarily shortwave-reflecting anthropogenic sulfates decrease and increase CWP in AZNM and NWUS, respectively, however, the shortwave-absorbing anthropogenic BC reduces CWP in both regions. Due to strong feedback via convective clouds, the radiative effects of anthropogenic aerosols on the summer radiation field are more closely correlated with the changes in CWP than the AOD. The radiative effect of the total anthropogenic aerosols is dominated by the anthropogenic sulfates that contribute more than 80% of the total AOD associated with the anthropogenic aerosols.

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“…Kim and Ek, 1995;Chen et al, 1996) and as part of the Project for Intercomparison of Land-surface Parameterization Schemes (PILPS, e.g. Chang and Ek, 1996;Chen et al, 1997;Liang et al, 1998;Lohmann et al, 1998;Qu et al, 1998;Chang et al, 1999); the study by Chang et al (1999) includes a comprehensive description of the current physics in the CAPS model landsurface scheme.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a land-surface scheme at Cabauw

Holtslag

2004

Theor. Appl. Climatol.

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SummaryWe study the response of the land-surface to prescribed atmospheric forcing for 31 May 1978 at Cabauw, Netherlands, using the land-surface scheme from the Coupled Atmospheric boundary layer-Plant-Soil (CAPS) model. Results from model runs show realistic daytime surface fluxes are produced using a canopy conductance formulation derived from Cabauw data (for 1987, a different year), and un-tuned parameterizations of root density (nearuniform with depth) and soil heat flux (reduced thermal conductivity through vegetation). Sensitivity of modelcalculated surface heat fluxes to initial values of soil moisture is also examined. Results of this study provide the land-surface 'base state' for a coupled land-atmosphere modeling study.

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Validation Study of the CAPS Model Land Surface Scheme Using the 1987 Cabauw/PILPS Dataset

Cited by 31 publications

References 32 publications

The Influence of Idealized Heterogeneity on Wet and Dry Planetary Boundary Layers Coupled to the Land Surface

The Influence of Idealized Heterogeneity on Wet and Dry Planetary Boundary Layers Coupled to the Land Surface

Direct and semi-direct radiative effects of anthropogenic aerosols in the Western United States: Seasonal and geographical variations according to regional climate characteristics

Evaluation of a land-surface scheme at Cabauw

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