HR: 0800h
AN: A21B-0732    [Abstracts]
TI: Inconsistencies in Tropical Tropopause Temperatures Between Radiosonde and GPS Radio Occultation Measurements
AU: * Spackman, J R
EM: spackman@huarp.harvard.edu
AF: Harvard University, Department of Chemistry and Chemical Biology, 12 Oxford Street, Cambridge, MA 02138 United States
AU: Leroy, S S
AF: Harvard University, Department of Chemistry and Chemical Biology, 12 Oxford Street, Cambridge, MA 02138 United States
AU: Moyer, E J
AF: Harvard University, Department of Chemistry and Chemical Biology, 12 Oxford Street, Cambridge, MA 02138 United States
AU: Ao, C O
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Weinstock, E M
AF: Harvard University, Department of Chemistry and Chemical Biology, 12 Oxford Street, Cambridge, MA 02138 United States
AU: Anderson, J G
AF: Harvard University, Department of Chemistry and Chemical Biology, 12 Oxford Street, Cambridge, MA 02138 United States
AB: Accurate temperature measurements at the tropical tropopause are critical to diagnosing the relationship between water vapor saturation mixing ratio and stratospheric water vapor and, accordingly, the mechanisms for stratosphere-troposphere exchange. The radiosonde network has provided the most accurate temperature record in the tropics to date, but a self-consistent temperature mapping of the tropical tropopause layer (TTL) with radiosonde data is impaired by (i) very limited spatial sampling, especially over the predominantly marine tropics, (ii) differences in radiosonde instrument packages, and (iii) solar radiation effects on reported temperatures. Global positioning system (GPS) radio occultation measurements offer a powerful approach to examining the temperature structure of the TTL that provides homogeneous spatial coverage of the tropics while still maintaining high vertical resolution. We use a GPS occultation data set obtained from the CHAMP satellite for 2001-2003 with retrievals performed at the Jet Propulsion Laboratory (JPL) and subjected to objective quality control. These occultations are compared with radiosonde measurements from the WMO global network that have been processed through the complex quality control of NCEP. GPS occultations and radiosondes show significant differences in (i) the mean cold-point tropopause temperature, (ii) the distribution of cold-point temperatures, and (iii) the height of the cold-point tropopause. We investigate differences between radiosonde and occultation climatologies of the TTL, paying special attention to the merits and deficiencies of each measurement approach. We also compare the GPS occultation retrievals of JPL to other retrieval algorithms to investigate potential biases. The temperature differences between GPS occultations and radiosondes at the cold-point tropopause could have profound implications for the water vapor budget of the stratosphere.
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3362 Stratosphere/troposphere interactions
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
DE: 0350 Pressure, density, and temperature
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting