ESRL/GMD and CIRES Initiating Upper Air Water Vapor and Ozone Observations

November 21, 2005

Sixty high altitude balloons carrying water vapor and ozone measurement instruments will be launched over the next 4 months to study dehydration and transport processes occurring in the tropical upper troposphere and in the arctic stratosphere. The first of the tropical soundings was launched at Heredia, Costa Rica on November 12, and the first Arctic sounding is scheduled for November 17 from Summit, Greenland. Soundings at Tarawa, Republic of Kiribati; Biak, Indonesia; San Cristobal, Galapagos; Sodankylš, Finland; Hilo, HI; and La Reunion will commence in the coming week.


The Earth's longest continuous in-situ stratospheric water vapor measurement record (25 years) above Boulder, Colorado by NOAA/ESRL/Global Monitoring Division (GMD) scientists, shows a steady increase as shown in the link below. Through the support of NOAA's Global Climate Observing System (GCOS) program office, GMD established a second in-situ stratospheric water vapor monitoring station in Lauder, New Zealand, in 2004 to determine the magnitude of the water vapor change in the southern hemisphere. The current study is designed to extend these water vapor measurements into the tropical troposphere. In addition, the Summit, Greenland and Sodankylš, Finland, measurements will address the question of whether stratospheric water vapor may be enhancing ozone depletion in the lower stratosphere in the Arctic. The water vapor measurements are being conducted with a new cryogenic frostpoint hygrometer developed by Cooperative Institute for Research in Envrionmental Sciences (CIRES) in cooperation with GMD, as well as with the time tested GMD frostpoint hygrometer that has been in use for over 25 years.


Atmospheric water vapor is a key greenhouse gas. In particular, small changes in water vapor in the upper troposphere and lower stratosphere can have long-term climatic effects. In addition, the ability of a warmer atmosphere to sustain increased amounts of water vapor provides a strong positive feedback to greenhouse gas induced warming. Warmer temperatures in the tropics make this region a primary source for tropospheric water vapor. Documenting possible changes in tropical tropospheric water vapor content are important for understanding water vapor climate forcing feedback mechanisms. In addition, the tropical tropopause exerts the primary control over water vapor entering the stratosphere. In the stratosphere, increased water vapor leads to a colder stratosphere and subsequent additional warming of the lower troposphere. These observations will also contribute to the validation of the NASA AURA and AQUA Earth Observing System (EOS) satellites.

More Information