Sensitivity of radiometric measurements of the atmospheric CO2 column from space.

Anthropogenic emissions of CO2 over the past century has altered significantly the global carbon cycle. Our understanding of the long-term climatic effects of these emissions would be improved greatly by satellite-based remote sounding of CO2. We provide an initial analysis of a simple satellite-based filter radiometer tuned to the spectral region around 6300 cm(-1) (approximately 1.

Measurements of the atmospheric carbon monoxide column with a ground-based length-modulated radiometer.

A ground-based remote sounding instrument that uses a length-modulated radiometer to measure the total atmospheric carbon monoxide (CO) column has been built. Measurements made in Toronto during August and September of 1994 showed average CO concentrations of 125 to 150 parts per billion in volume (ppbv, parts in 10(9)). Similar measurements made in October at a rural site 80 km north of Toronto showed concentrations of approximately 100 ppbv.

Characterization of the length-modulated radiometer.

The development of the length-modulated radiometer (LMR), which is a new type of correlation radiometer for remote sounding, is described. Factors that affect the performance of the LMR are identified and, whenever possible, are minimized. Laboratory measurements of the radiometric response of a LMR filled with carbon monoxide are presented and compared with theoretical calculations.