This is the Download Page for the Central Valley PBL Height dataset. Yearly and monthly subsets are available for download from each station in .txt format. Each file contains 45-minute interval estimations of the PBLH and up to three mixing layer heights (MLH) per interval. MLH’s are ordered by magnitude of the vertical aerosol backscatter gradient. Additionally, each timestep includes flags for data quality. For definitions of the flag codes and a full chart of data availability, see the corresponding drop-downs below.
| Station | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 |
|---|---|---|---|---|---|---|
| Bakersfield | Oct 14 – Dec 30 | Full Year | Jan 1-5, Nov 1 – Dec 30 | Full Year | Full Year | Jan 1 – Nov 23 |
| Fresno | Oct 14 – Dec 30 | Full Year | None | Sep 1 – Dec 31 | Full Year | Jan 1 – May 10, Oct 12 – Dec 31 |
| Riverside | Oct 14 – Dec 30* | Jan 1 – Oct 28* | None | Jun 1 – Dec 31 | Full Year | Jan 1 – Jun 15 * |
| Visalia | None | None | Jan 11 – Jan 28, Nov 1 – Dec 31 | Full Year | Full Year | Jan 1 – Aug 8 |
| Yuba City | None | Sept 1 – Dec 31 | Full Year | Jan 1 – Sept 13 | Full Year | Full Year |
*Occasional Missing Days
| Code | Flag Description |
|---|---|
| M | Missing data during time interval |
| M1 | Bad signal; negative aerosol backscatter |
| M2 | No signal; all noise |
| M3 | Ambiguous signal; signal is too weak to overcome artificial gradient caused by incomplete overlap; or, the PBLH is too low to rise above the artificial gradient |
| M4 | Signal is too weak to detect a significant guess |
| C | Low cloud |
| C1 | Guess is above cloud layer; potentially cloud-topped boundary layer; potentially misidentified PBLH given weak below-cloud aerosols |
| C2 | Weak signal beneath cloud |
| P | Precipitation (can potentially erroneously flag extreme aerosol load) |
| A1 | Clear-sky timestep after clouds or precip; potential uncertainty after cloudy conditions |
| A2 | Clear-sky timestep after large jump; potential uncertainty after discontinuity |
| S | Strong positive backscatter gradient beneath guess; potentially a smoke layer |
| L | Large upward jump |
Ceilometers provide built-in estimates of PBLH and MLH. However, these methods are highly susceptible to noise and short-lived artifacts that preclude them from being reliable measurements of the PBL in the Central Valley, where transient aerosol layers are common. In developing our own algorithm, we keep the same definition of MLH as used by the ceilometer algorithms. Our definition of the PBLH diverges in that we include additional constraints to ensure physical accuracy in our estimations.
Mixed Layer Height: A significant aerosol layer in the lower atmosphere characterized by a temporally persistent, vertical gradient in the aerosol backscatter. Multiple mixed layers can coexist temporally, and up to three are captured by the algorithm. Mixed layer heights are captured during both day and night time.
Planetary Boundary Layer Height: The boundary between the turbulent boundary layer and the free troposphere, measured indirectly by a temporally persistent, vertical gradient in the aerosol backscatter. Given the physical properties of a boundary layer, such as temporal continuity, morning growth, and afternoon decay, additional constraints are applied to PBLH detection to ensure physical accuracy. Since the nighttime is dominated by residual aerosol layers above 300 meters and our signal is dominated by noise in the lowest 300 meters, we do not attempt to measure a nocturnal boundary layer. Thus, we only make PBLH estimates during the daytime, when convective mixing supports our assumed relationship between aerosols and boundary processes.
Mixed Layer Height: A significant aerosol layer in the lower atmosphere characterized by a temporally persistent, vertical gradient in the aerosol backscatter. Multiple mixed layers can coexist temporally, and up to three are captured by the algorithm. Mixed layer heights are captured during both day and night time.
Planetary Boundary Layer Height: The boundary between the turbulent boundary layer and the free troposphere, measured indirectly by a temporally persistent, vertical gradient in the aerosol backscatter. Given the physical properties of a boundary layer, such as temporal continuity, morning growth, and afternoon decay, additional constraints are applied to PBLH detection to ensure physical accuracy. Since the nighttime is dominated by residual aerosol layers above 300 meters and our signal is dominated by noise in the lowest 300 meters, we do not attempt to measure a nocturnal boundary layer. Thus, we only make PBLH estimates during the daytime, when convective mixing supports our assumed relationship between aerosols and boundary processes.
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