Observation of Stratospheric Water Vapor

Science Background and Motivation

Water vapor in the Earth's atmosphere plays a significant role in maintaining Earth's global temperature. The temperature of the tropical tropopause largely determines the amount of water that is transported from the troposphere into the stratosphere. However, very few direct observations of water vapor at the tropical tropopause exist. The Ticosonde observational site, which is located in the deep tropics, conducts monthly in situ measurements of water vapor at the tropical tropopause and in the tropical lower stratosphere. It is the only site that conducts these difficult observations throughout the year. No other site does year round measurements of water vapor in the lower stratosphere, making our site the only one of its kind. NASA supports validations of satellite remote sensing water vapor measurements, including those from the Microwave Limb Sounder (MLS).


Climatology: Stratospheric water vapor

Ticosonde has measured upper tropospheric and lower stratospheric water vapor since 2005. The long term climatology encompasses over 200 soundings for stratospheric water vapor over more than 12 years.

The climatology shows the stratospheric "tape recorder". There tropopause, which is indicated in this figure as black line, is significantly colder during November through April and dries the air crossing the tropopause to lower mixing ratios than the warmer tropopause during May through October. The slow vertical ascent of air in the lower stratosphere lifts this seasonal variation of water vapor at the tropical tropopause, creating a slanted sequence of minima and maxima in the time height climatology of tropical stratospheric water vapor.

Climatology: Tropospheric water vapor

The soundings provide additional information about tropospheric water vapor and help to visualize the seasons at Costa Rica.

The middle troposphere during November through March is significantly drier than during the rainy season April through October. However, the relative humidity levels in the uppermost troposphere remain high throughout the year.

Papers and Presentations

Ticosonde-TC4 Project DOI: 10.1029/2009JD013073

Corti, T., B. P. Luo, Q. Fu, H. Vömel, and T. Peter, The impact of cirrus clouds on tropical troposphere-to-stratosphere transport, Atmos. Chem. Phys., 6, 2539-2547, 2006. Davis, S., D. Hlavka, E. Jensen, K. Rosenlof, S. Schmidt, S. Borrmann, W, Frey, P. Lawson, H, Vömel, T.P. Bui (2010), In situ and lidar observations of subvisible cirrus clouds during TC4, J. Geophys. Res., 115, D00J17, doi:10.1029/2009JD013093.

Davis S. M., K. H. Rosenlof, B. Hassler, D. Hurst, W. G. Read, H. Vömel, H. Selkirk, M. Fujiwara, and R. Damadeo (2016): The Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database: A long-term database for climate studies, Earth Syst. Sci. Data, 8, 461-490, doi:10.5194/essd-8-461-2016.

Fetzer, E. J., W. G. Read, D. Waliser, B. H. Kahn, B. Tian, H. Vömel, F. W. Irion, H. Su, A. Eldering, M. de la Torre Juarez, J. Jiang, and V. Dang (2008): Comparison of upper tropospheric water vapor observations from the Microwave Limb Sounder and Atmospheric Infrared Sounder, J. Geophys. Res., 113, D22110, doi:10.1029/2008JD010000.

Fujiwara, M., H. Vömel, F. Hasebe, M. Shiotani, S.-Y. Ogino, S. Iwasaki, N. Nishi, T. Shibata, K. Shimizu, E. Nishimoto, J. Valverde-Canossa, H. B. Selkirk and S. J. Oltmans (2010), Seasonal to decadal variations of water vapor in the tropical lower stratosphere observed with balloon-borne cryogenic frost point hygrometers, J. Geophys. Res., 115, D18304, doi:10.1029/2010JD014179.

Khaykin, S. M., V. A. Yushkov, L. I. Korshunov, A. N. Lukyanov , J. P. Pommereau, J. Nielsen, and H. Vomel (2010), Humidity of the tropical lower stratosphere: Observations and analysis, Izvestiya Atmospheric and Oceanic Physics, 46, 76-84.

Miloshevich, L. M., H. Vömel, D. N. Whiteman, T. Leblanc (2009) Accuracy assessment and correction of Vaisala RS92 radiosonde water vapor measurements, , J. Geophys. Res., 114, doi:10.1029/2008JD011565.