Observations of Spatial Variations in Convective Boundary Layer Structure over a Heterogeneous Land Surface during IHOP

Observation of variable ABL structures over a heterogeneous land surface

Songlak Kang and Kenneth J. Davis

The International H2O Project (IHOP_2002) was held over the Southern Great Plains (SGP) from 13 May to 25 June 2002 to obtain more accurate and reliable moisture data in the air for better understanding the initiation and intensity of convective rainfall. Especially, on the five Boundary Layer Heterogeneity (BLH) mission days during this IHOP_2002 field experiment, the data set collected over the western track, a 50-km north-south track along the longitude of 100.6 W, provides a great opportunity to study the interaction between land surface and daytime atmospheric boundary layer (ABL). Here, using the data set, the interaction on the meso- scale is documented. First, flux tower measurements are used to extricate the factors causing the surface heterogeneity represented in the surface radiation temperature and surface flux distribution. Second, data collected from the repeated low-level flights of the University of Wyoming King Air (UWKA) are used to investigate the scale of the interaction between land-surface and daytime ABL under the different conditions in land-surface and ambient air. Especially, the degree to which stationary ABL circulations are present and linked to surface heterogeneity is analyzed. Third, the extent to which low-level surface heterogeneity extends through the entire depth of the ABL is analyzed using upper-level in situ aircraft data and airborne lidar observations. Through this study, we can verify the significant influence of the surface heterogeneity on the ABL structure.