Search Results

You are looking at 1 - 9 of 9 items for :

  • Cloud forcing x
  • Monthly Weather Review x
  • International H2O Project (IHOP) Boundary Layer Processes x
  • Refine by Access: All Content x
Clear All
John R. Mecikalski, Kristopher M. Bedka, Simon J. Paech, and Leslie A. Litten

( Table 2 ), and possess environments in which moisture for CI was not a factor limiting cumulus growth and rainfall. The 6 and 12 July, and 28 August 2004 CI events were also selected as the synoptic-scale forcing was relatively weak, storm motions were relatively slow (≤15 m s −1 ), and both cloud and storm motions were generally uniform along one velocity vector regardless of cloud size (i.e., cumuli in both pre- to post-CI state). Weak vertical shear and the lack of a deep dry layer within the

Full access
Margaret A. LeMone, Fei Chen, Mukul Tewari, Jimy Dudhia, Bart Geerts, Qun Miao, Richard L. Coulter, and Robert L. Grossman

3 . Section 4 compares the observed and modeled CBL structure from kilometer-scale to mesoscale (∼10–100 km), drawing from some sensitivity runs to help interpret the model CBL convective structure. The results are summarized in section 5 . 2. Data collection and analysis The four fair-weather days examined had scattered clouds and wind from approximately south-southwest to southeast ( Table 1 ). Winds at 65 m above ground level (AGL) vary from 3.9 m s −1 on 30 May to 9.4 m

Full access
F. Couvreux, F. Guichard, P. H. Austin, and F. Chen

variability. 2. Methodology Fully coupled surface–atmospheric mesoscale models are powerful tools for the study of land–atmosphere interactions. Their representations of moist processes, cloud cover, and surface fluxes are however still incomplete (e.g., Betts 2004 ), and the nonlinear coupling between surface and atmosphere makes it difficult to isolate individual physical processes affecting boundary layer heterogeneity. The alternative and complementary approach employed in section 2b is to study

Full access
Steven E. Koch, Wayne Feltz, Frédéric Fabry, Mariusz Pagowski, Bart Geerts, Kristopher M. Bedka, David O. Miller, and James W. Wilson

). Measurements of aerosol backscatter, cloud optical depth, depolarization, water substance, and temperature were all produced by SRL, but of greatest interest to this study are mixing ratio measurements made with a temporal resolution of 2 min and a vertical resolution that varied from ∼30 to 200 m. HARLIE is an aerosol backscatter lidar operating in a conical scanning mode at a 45° elevation angle at a rate of once every 12 s with range resolution of 30 m. By adding all profiles from each scan, backscatter

Full access
Monica Górska, Jordi Vilà-Guerau de Arellano, Margaret A. LeMone, and Chiel C. van Heerwaarden

observations of sensible and latent heat fluxes at one surface station (station 7) along the aircraft track. Argonne National Laboratory operated another surface flux site close to the track, a grass site at Smileyberg, Kansas, which measured CO 2 fluxes ( Coulter et al. 2006 ). These measurements from station 7 and the Smileyberg site are used for comparison with the surface fluxes in the analysis of the single-value method and as an input surface forcing in the numerical experiments ( Fig. 2 ). b. Large

Full access
Robert J. Conzemius and Evgeni Fedorovich

input flux data. The flux data are indicative of the strong insolation and absence of cloud cover that occurred during this particular case. The atmospheric CBL depths were determined from the Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE; Guerra et al. 1999 ) data. HARLIE is a 1- μ m-wavelength aerosol backscatter lidar that was deployed during IHOP_2002 at the Homestead site south-southwest of Beaver. HARLIE makes atmospheric scans at a constant elevation angle of 45° and

Full access
Roger M. Wakimoto and Hanne V. Murphey

1. Introduction There has been an increased emphasis placed on understanding the initiation of deep convection during the summer months when large-scale forcing is weak or absent (e.g., Wilson et al. 1998 ). Indeed, Olsen et al. (1995) have shown a dramatic drop in the ability to forecast convection during the summer when major precipitation events occur. The main reason for this difference in skill is that winter season precipitation events are predominately associated with

Full access
S. B. Trier, F. Chen, K. W. Manning, M. A. LeMone, and C. A. Davis

anomalies specific to the 1993 warm season could not account for the precipitation anomaly, but, similar to Beljaars et al. (1996) , they concluded that heavier precipitation was promoted by wetter soil upstream. In contrast, Paegle et al. (1996) found a negative feedback between precipitation and upstream soil wetness for July 1993. They concluded that drier soil upstream resulted in stronger PBL forcing of the nocturnal low-level jet (LLJ), which led to enhanced convergence and water vapor

Full access
John H. Marsham, Stanley B. Trier, Tammy M. Weckwerth, and James W. Wilson

impossible to visually track wave crests from one SUR scan to another. A Hovmöller diagram ( Fig. 6 ) of reflectivity along the yellow line shown in Fig. 5 toward the IE3 cells initiating in Fig. 5a showed weak reflectivity signals (approximately −5 dB Z ) propagating at speeds between 3 and 9 m s −1 for approximately 1 h. These are in some cases later connected to stronger reflectivities from clouds (i.e., are consistent with initiation by the wave). Figure 6 does not allow the wave source to be

Full access