Value-Added Product Estimates Planetary Boundary-Layer Height from Radiosondes

Published: 12 September 2013
Example quicklook plot from the VAP showing the sub-sampled potential temperature (black) and potential temperature lapse rate (red) from a single radiosonde along with the estimates of PBL height from the three methods.

The planetary boundary-layer (PBL) height (or mixing-layer depth) can vary significantly with time due to a number of factors including large-scale dynamics, cloudiness, convective mixing, and the diurnal cycle of solar radiation. The structure and depth of the PBL is important to a wide range of atmospheric processes including cloud formation; aerosol mixing, transport, and transformation; and chemical mixing, transport, and transformation. The data for a new ARM value-added product (VAP) that estimates PBL height from radiosonde measurements (PBLHT) are now available at the ARM Data Archive for all sites.

Example plot showing the PBL height calculated using the Heffter method for 12 years at the Southern Great Plains (SGP). Dark green points indicate “good” PBL height estimates where no QC bits are triggered; light green points indicate estimates where the PBL height is considered of “indeterminate” quality.

The VAP implements three different methods for estimating PBL height. Two methods involve gradients in the potential temperature profile, while a third method is based on the profile of the bulk Richardson number. One of the methods also classifies the PBL into regimes (stable, convective, or neutral). The differences among estimates from the various methods can be considered a partial estimate of the uncertainty in the PBL height values. The VAP produces both detailed files for each radiosonde launch and annual summary files containing a time series of PBL height over the year.

More information is available at the VAP web page. To access these data, log in to the Data Archive. (Go here to request an account.)