#  COBRA 2000 

 



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During August of 2000, COBRA conducted in-situ airborne measurements of CO2, CO, H2O, and meteorological parameters in the lower- and mid-troposphere over the U.S., exploring methods for quantifying terrestrial sources and sinks of CO2 at regional and continental scales. In addition, flask measurements of O2/N2 (Scripps) and CH4, N2O, SF6, d13C (NOAA CMDL) were conducted.

   ![COBRA-2000](/sites/g/files/omnuum1576/files/styles/hwp_1_1__360x360_scale/public/atmos/files/img-data_resources-cobra_2000.gif?itok=m4udR9sT) 

 

The COBRA airborne platform is the [University of North Dakota Cessna Citation II](https://aero.und.edu/), a straight-wing twin-engine fanjet suited for intensive vertical profiling of the entire atmosphere including the PBL (planetary boundary layer). The flight duration of 3.5~4 hours allows coverage of continental scales. In addition to the science payload, the plane carries two pilots and two science crew.

   ![COBRA 2000 flight tracks](/sites/g/files/omnuum1576/files/styles/hwp_1_1__360x360_scale/public/atmos/files/img-data_resources-harvard_forest_data_archive_exchange-cobra_flight.jpeg?itok=tvpjFImp) 

 

In COBRA-2000, flights originated at Grand Forks, ND, the home base for the UND Citation II. A [Lagrangian experiment](/atmospheric_sciences_data_resources-cobra-2000-lagrangian "COBRA-2000 : Lagrangian Regional-scale Experiment") was performed first, in Southern Manitoba and North Dakota. After a transit to Centennial Airport near Denver, a day was spent surveying through Wyoming and Idaho. Then a transit (Southern tier survey) was executed from Denver to Boston (Hanscom Field), with numerous dips and stops. Next two days of regional flying were conducted over Maine. Finally a survey was made across the Northern Tier states back to Grand Forks, ending with regional Lagrangian flights over the tall tower at WLEF.


[**Lagrangian Regional-scale Experiment**](/atmospheric_sciences_data_resources-cobra-2000-lagrangian "COBRA-2000 : Lagrangian Regional-scale Experiment")

Airmass-following (Lagrangian) experiments possess the potential for minimizing the advection term in the budget. We tested this Lagrangian approach in COBRA-2000 by conducting several flights sampling an air mass for 12 - 24 hours. We developed and used STILT model to simulate the motions of tracer particles backwards in time and used it to follow an airmass through a 24hour period.

[**Large-scale Surveys**](/atmospheric_sciences_data_resources-cobra-2000-largescale_survey "COBRA-2000 : Large-scale Surveys")

Two large-scale, trans-continental surveys were conducted in COBRA-2000. The sampling strategy generated cross-sections showing distinct fingerprints of influences at the continental scale. Moreover, results show how signatures of underlying sources and sinks are clearly observable in the atmosphere using aircraft sampling.