Stratocumulus Cloud-Top Height Estimates and Their Climatic Implications Export

@article{citeulike:5687162, abstract = {A depth-dependent boundary layer lapse rate was empirically deduced from 156 radiosondes released during six month-long research cruises to the southeast Pacific sampling a variety of stratocumulus conditions. The lapse-rate dependence on boundary layer height is weak, decreasing from a best fit of 7.6 to 7.2 K km\&\#8722;1 as the boundary layer deepens from 800 m to 2 km. Ship-based cloud-base heights up to 800 m correspond well to lifting condensation levels, indicating well-mixed conditions, with cloud bases \&\#62;800 m often 200\&\#8211;600 m higher than the lifting condensation levels. The lapse rates were combined with Moderate Resolution Imaging Spectrometer 11-\&\#956;m-derived cloud-top temperatures and satellite microwave-derived sea surface temperatures to estimate stratocumulus cloud-top heights. The October-mean cloud-top height structure of the southeast Pacific was then spatially and diurnally characterized. Coastal shoaling is apparent, but so is a significant along-coast cloud-top height gradient, with a pronounced elevation of the cloud-top heights above the Arica Bight at \&\#8764;20\&\#176;S. Diurnal cloud-top height variations (inferred from irregular 4-times-daily sampling) can locally reach 250 m in amplitude, and they can help to visualize offshore propagation of free-tropospheric vertical motions. A shallow boundary layer associated with the Chilean coastal jet expands to its north and west in the afternoon. Cloud-top heights above the Arica Bight region are depressed in the afternoon, which may mean that increased subsidence from sensible heating of the Andes dominates an afternoon increase in convergence/upward motion at the exit of the Chilean coastal jet. In the southeast Atlantic during October, the stratocumulus cloud-top heights are typically lower than those in the southeast Pacific. A coastal jet region can also be identified through its low cloud-top heights. Coastal shoaling of the South Atlantic stratocumulus region is mostly uniform with latitude, in keeping with the more linear Namibian/Angolan coastline. The southeast Atlantic shallow cloudy boundary layer extends farther offshore than in the southeast Pacific, particularly at 15\&\#176;S.}, author = {Zuidema, Paquita and Painemal, David and de Szoeke, Simon and Fairall, Chris}, citeulike-article-id = {5687162}, citeulike-linkout-0 = {http://dx.doi.org/10.1175/2009JCLI2708.1}, day = {1}, doi = {10.1175/2009JCLI2708.1}, journal = {Journal of Climate}, keywords = {boundary\_layer, cloud, low\_stratus, modis, remote\_sensing, satellite, stratocumulus, technique}, month = {September}, number = {17}, pages = {4652--4666}, posted-at = {2009-08-31 06:53:30}, priority = {3}, title = {Stratocumulus Cloud-Top Height Estimates and Their Climatic Implications}, url = {http://dx.doi.org/10.1175/2009JCLI2708.1}, volume = {22}, year = {2009} }

TY - JOUR ID - citeulike:5687162 L3 - citeulike-article-id:5687162 N2 - A depth-dependent boundary layer lapse rate was empirically deduced from 156 radiosondes released during six month-long research cruises to the southeast Pacific sampling a variety of stratocumulus conditions. The lapse-rate dependence on boundary layer height is weak, decreasing from a best fit of 7.6 to 7.2 K km−1 as the boundary layer deepens from 800 m to 2 km. Ship-based cloud-base heights up to 800 m correspond well to lifting condensation levels, indicating well-mixed conditions, with cloud bases >800 m often 200–600 m higher than the lifting condensation levels. The lapse rates were combined with Moderate Resolution Imaging Spectrometer 11-μm-derived cloud-top temperatures and satellite microwave-derived sea surface temperatures to estimate stratocumulus cloud-top heights. The October-mean cloud-top height structure of the southeast Pacific was then spatially and diurnally characterized. Coastal shoaling is apparent, but so is a significant along-coast cloud-top height gradient, with a pronounced elevation of the cloud-top heights above the Arica Bight at ∼20°S. Diurnal cloud-top height variations (inferred from irregular 4-times-daily sampling) can locally reach 250 m in amplitude, and they can help to visualize offshore propagation of free-tropospheric vertical motions. A shallow boundary layer associated with the Chilean coastal jet expands to its north and west in the afternoon. Cloud-top heights above the Arica Bight region are depressed in the afternoon, which may mean that increased subsidence from sensible heating of the Andes dominates an afternoon increase in convergence/upward motion at the exit of the Chilean coastal jet. In the southeast Atlantic during October, the stratocumulus cloud-top heights are typically lower than those in the southeast Pacific. A coastal jet region can also be identified through its low cloud-top heights. Coastal shoaling of the South Atlantic stratocumulus region is mostly uniform with latitude, in keeping with the more linear Namibian/Angolan coastline. The southeast Atlantic shallow cloudy boundary layer extends farther offshore than in the southeast Pacific, particularly at 15°S. IS - 17 JF - Journal of Climate EP - 4666 TI - Stratocumulus Cloud-Top Height Estimates and Their Climatic Implications VL - 22 SP - 4652 KW - boundary_layer KW - cloud KW - low_stratus KW - modis KW - remote_sensing KW - satellite KW - stratocumulus KW - technique AU - Zuidema, Paquita AU - Painemal, David AU - de Szoeke, Simon AU - Fairall, Chris PY - 2009/09/01/ UR - http://dx.doi.org/10.1175/2009JCLI2708.1 ER -