Boundary-Layer Characterization Projects

US Climate Reference Network
Rainbow over Buffalo, South Dakota CRN site

Rainbow over Buffalo, South Dakota CRN site

ARL manages, operates, and maintains the U.S. Climate Reference Network (USCRN) which includes 139 stations in the lower 48 (114); Alaska (23); and Hawaii (2), which provides long-term robust climate observations that are necessary to document climate change trends for the United States. The current plan is to extend the number of stations in Alaska to 29-30 by the end of fiscal year 2026. The network is now entering its 3rd decade of service, having begun initial operations in 2002. ARL’s activities focus on:
  • advancing the quality and quantity of reference observations;
  • evaluating select observing systems for their ability to satisfy ongoing and evolving climate requirements;
  • improving the understanding of air-surface interactions; and
  • analyzing long-term observational datasets and models to understand climate variability and change.
Researchers at ATDD perform extensive evaluation and maintenance of the array of instruments and the infrastructure for the USCRN. Additionally, ARL conducts energy, water, and greenhouse gas flux measurements and analyzes their relationships. A predictive understanding of the surface energy budget and related feedbacks is critical to the understanding of climate forcing factors at the land surface and the ability to credibly predict future conditions, especially those related to water resources. The USCRN provides high quality, reference-grade measurements of critical primary climate observations of air temperature, precipitation, and soil moisture and temperature; as well as secondary observations of wind speed, land surface temperature, and solar radiation to assist in the quality control of the primary measurements, and and also to translate that information for decision-makers to understand how and why climate has changed and what changes might occur in the future.


Sensor calibration and installation at the DCNet site on the Department of Commerce Building in Washington, DC.

DCNet is a meteorology research program established by NOAA for the National Capital Region (NCR) as a response to potential threats following the September 11, 2001 attacks on the U.S. Initial goals of DCNet were to explore variations in model inputs for both numerical weather prediction (NWP) as well as atmospheric transport and dispersion models (AT&D), to assimilate urban observations into both numerical weather prediction and atmospheric transport models, and the provision of real-time meteorological observations over the greater NCR to support current numerical weather prediction models as well as provide the driving meteorological observations for atmospheric transport and dispersion models. DCNet data provide information on large urban complex covering a broad spectrum of weather conditions, permitting an unparalleled description of the atmospheric flow behavior over a complex urban area largely unaffected by major terrain inconsistencies. The network collected standard meteorological data and measurement of characteristics of atmospheric turbulence at 16 locations; only one DCNet (U.S. Department of Commerce Herbert C. Hoover Building, USDOC HCHB) site within the NCR is currently active. HCHB was installed in 2003; HCHB has a primary (Hoover-North) and secondary (Hoover-South) monitoring station. Data archiving began in 2004.

Surface Flux Measurements

ARL partners with other laboratories and universities to develop micrometeorological methods to observe lower land/atmosphere interactions including surface fluxes and controls, better understand the linkages to the boundary layer processes and feedbacks, and to better represent these processes in weather forecasting models. Field experiments are designed to replicate sampling of point measurements known to be highly variable such as soil moisture, soil temperature, and vertical atmospheric gradients. More details about the field experiments in which ATDD has recently been involved are discussed in more detail below. ARL is also developing new and innovative technologies (UAS platforms and sensors) to observe surface and atmospheric variables (i.e. air temperature, humidity, wind, land surface temperature) and to obtain derived quantities from these measurements (e.g., Normalized Difference Vegetation Index, surface heat fluxes, etc.).