A Critical Zone Observatory is an environmental laboratory, focused on the interconnected chemical, physical and biological processes shaping Earth's surface.
Our nine observatories span a range of climatic, ecologic, geologic, and physiographic environments, from California to Puerto Rico.
Each CZO is working toward a common set of resources, which will enable us to compare whole-watershed Carbon, energy and mass balances across a variety of settings.
NSF's Cheryl Dybas has completed a series of articles describing research at the original six CZOs. Read her articles and download a copy of a new report entitled "Discoveries in the Critical Zone: Where Life meets Rock".
Our CZO spans from the Continental Divide (4120 m) in the Front Range of the Rockies to the western edge of the Plains (1480 m). Our research takes advantage of large differences in elevation, climate, geologic history, and weathering regime.
NW 40.158241, -105.700648; SE 39.847222, -105.002685
Approx center point lat,long: 39.977774, -105.356698
The Calhoun CZO is located in a region with an environmental history that involves some of the most serious agricultural land and water degradation in N America 5 themes:Ecohydrological Recovery; Biogeochemical Decoupling; Erosion-induced Carbon Dynamics; Human-CZ Interactions; Dynamic Persistence of Alternative States
NW 34.662333, -81.782834; SE 34.544231, -81.649356
Approx center point lat,long: 34.6035, -81.7160
Our CZO is located in the Piedmont and Atlantic Coastal Plain which provides drinking water to a million people in Delaware and Pennsylvania. Our research focusses on water, carbon and mineral fluxes (temporal and spatial integration), including human impacts.
NW 40.16, -76.3; SE 39.4, -75.0
Approx center point lat,long: 39.698520, -75.626309
NW 40.7263, -124.3490; SE 39.2406, -122.6680
Approx center point lat,long: 39.718588, -123.652794
NW 46.352885, -97.363941; SE 39.611674, -88.142584
Approx center point lat,long: 39.98731004722222, -88.66616; 41.72710555555556, -91.77335833333333; 44.1677, -94.0034
Secondary Bounding lat,long:
Minnesota River: NW 46.3530, -97.3517 ; SE 43.2307, -93.0885Clear Creek: NW 41.7680, -92.0185; SE 41.6530, -91.5615Sangamon: NW 40.5670, -89.5405; SE 39.6110, -88.1425
Our CZO comprises elevation (climate) gradients on rhyolite, granite and schist in northern New Mexico and Southern Arizona. Our research is especially pertinent to climate variations of arid and semi-arid systems.
NW 36.018774, -110.847624; SE 32.414320, -106.389630
Approx center point lat,long: 32.427379, -110.757822; 35.889167, -106.532206
Secondary Bounding lat,long:
Catalina: NW 32.5630, -100.8480; SE 32.4140, -100.7240Jemez: NW 36.0188, -106.6724; SE 35.7826, -106.3895
Our CZO is located in a forested, mountainous, and wet region of northeastern Puerto Rico. Our research compares two adjacent watersheds, which are underlain by differing bedrock types and exhibit differing weathering characteristics,
NW 18.410405, -65.861106; SE 18.187889, -65.669475
Approx center point lat,long: 18.279715, -65.763837
Soil carbon is the largest terrestrial C store but remains a large source of uncertainty in global climate models due to scaling and process understanding. Reynolds Creek CZO is focused on the quantification of soil carbon and the critical zone processes governing it.
NW 43.312983, -116.859446; SE 43.060888, -116.688138
Approx center point lat,long: 43.205809, -116.749823
Our CZO is a forested, first-order catchment on shale bedrock in a temperate climate. Our research promotes understanding of how the forested catchment evolves over multiple timescales ranging from the meteorological to the geological.
NW 40.731944, -78.073333; SE 40.589444, -77.846759
Approx center point lat,long: 40.65, -77.95
SSCZO is based in the southwestern Sierra Nevada with sites ranging from oak savannah to subalpine forest, crossing the rain-snow transition zone. Research at these sites focuses on water, nutrient, and soil fluxes; and landscape and climate changes cross space and time.
NW 37.739566, -120.061087; SE 36.172095, -118.333915
Approx center point lat,long: 37.056960, -119.195966
A Critical Zone Observatory is an environmental laboratory, a platform for research, that functions at the catchment/watershed scale focused on the interconnected chemical, physical and biological processes shaping Earth's surface.
Each Critical Zone Observatory works on shared CZO goals but also focuses on aspects of Critical Zone science that fit the strengths of its investigators and its environmental setting. Each CZO consists of field sites within a watershed. The sites are instrumented for a variety of hydrogeochemical measurements as well as sampled for soil, canopy and bedrock materials.
Each CZO is run by a team of cross-disciplinary scientists who have expertise in fields including hydrology, geochemistry, geomorphology, pedology, ecology and climatology. Participants also include faculty, staff, postdocs, graduate and undergraduate students, and interested members of the general public.
The research at each CZO includes field and theoretical approaches, including modeling studies. Each CZO also emphasizes education and outreach, including students from K-12 to undergraduate and graduate levels.
Each CZO is working toward a common infrastructure while also establishing additional resources that advance their unique strengths. All are supported by the US National Science Foundation (NSF), Geoscience Directorate, Earth Science Division. And all work together with partnering organizations to share existing infrastructure built with other programs.
CZOs provide essential datasets and a coordinated community of researchers that integrate hydrologic, ecological, geochemical, and geomorphic processes from grain-to-watershed scales. CZOs are the lenses through which the rich complexity of interactions between the lithosphere, pedosphere, hydrosphere, biosphere, and atmosphere can be brought into focus. CZOs are poised to reveal how mass and energy fluxes interact with life and rock over geological timescales, for example processes that transform bedrock into soils, and how the same coupled processes enact feedbacks between the Critical Zone and changing climate and land use over timescales of human decision making.
The U.S. National CZO Program is centered on nine observatories located in differing climatic and physiographic environments, from California to Puerto Rico. These CZOs work with their European counterpart observatories funded by the European Commission (see SoilTrEC).
Although funded separately, the nine U.S. CZOs work together to progress Critical Zone science and maximize their combined resources and potential. More specifically, the U.S. CZOs are working together to help determine how the Critical Zone operates and evolves - including a predictive ability for how it will respond to projected changes in climate and land use. Together, they are building a shared platform for broader research.
The wide range of climates, histories, and environmental settings spanned by the CZOs enable invaluable collaborations and intercomparisons. The CZOs are interlinked on many levels and include shared infrastructure, knowledge, data and meetings.
Catchments and river basins represent natural organizing scales for terrestrial water, energy, and weathering cycles, as well as human impacts. Of course, they must be viewed in the larger regional geologic and geomorphic context.
The CZOs focus on whole-watershed energy, carbon and mass balances.
Observatories studying the Critical Zone are being built around the Globe. The US NSF CZO Program is collaborating with many of them.
To view some international field sites, see