Executive Summary
The Unified Ceilometer Network (UCN) Quality Assurance Project Plan (QAPP) establishes how the U.S. EPA and Hampton University will operate a national platform that collects, processes, and shares ceilometer‐derived atmospheric data—chiefly the hourly mixing‑layer height (MLH) required by the Photochemical Assessment Monitoring Stations (PAMS) program. This joint effort standardizes data streams from both PAMS and non‑PAMS sites, easing the technical burden on state, local, and tribal air‑monitoring agencies and improving confidence in MLH information used for ozone modeling and air‑quality planning.
Scope and Timeframe
- The QAPP governs the full data life‑cycle—secure transmission from field sites, automated processing, quality control, archiving, and web‑based distribution of products and diagnostics.
- The current period of performance runs 2025 – 2029 under an interagency memorandum of understanding.
Core Deliverables
- Standard products: hourly MLH plus ancillary outputs such as nocturnal boundary‑layer height, residual‑layer height, aerosol/cloud/precipitation flags, and real‑time backscatter profile graphics.
- UCN web portal: near‑real‑time visualization, historical archive access, and automated status dashboards for participating sites.
- Training & documentation: on‑line guides covering instrument operation, data submission, and best‑practice interpretation.
Quality Management
The plan embeds rigorous controls:
- Retrievals failing a ± 200 m standard‑deviation threshold or affected by precipitation/cloud contamination are automatically excluded.
- A 50 % data‑completeness requirement is enforced for both 10‑minute and hourly averages.
- Roles are clearly defined—from EPA technical and QA leads to Hampton University data managers—ensuring independent oversight and continuous improvement.
Strategic Value
By harmonizing heterogeneous ceilometer networks through peer‑reviewed algorithms and transparent QA, the UCN delivers a robust, scalable foundation for:
- Regulatory compliance—fulfilling PAMS MLH reporting with a single, authoritative pipeline.
- Scientific insight—providing high‑resolution boundary‑layer data that sharpen chemical‑transport model performance and support emerging research on ozone, smoke, and urban‑pollution events.
- Operational efficiency—reducing redundant local processing, centralizing expertise, and offering turnkey visualization and download tools for agencies, researchers, and the public.
Collectively, the QAPP positions the UCN as a national resource that strengthens air‑quality management while advancing atmospheric science.