Recorded presentation5B.1
Thermal Structure and Variability of the Tropical Tropopause Layer Derived from AIRS Observations
Baijun Tian, JPL, Pasadena, CA; and E. J. Fetzer, D. E. Waliser, and B. H. Lambrigtsen
The climatological structure and variability of the tropical tropopause layer (TTL), and mechanisms behind them, are topics of current active research. In particular, documenting and understanding the thermodynamic structure and variability of the TTL is very important to quantify climate change and variability, and to understand mechanisms of stratosphere-troposphere exchange. Furthermore, current interests in stratospheric dehydration and water vapor trends, and the formation mechanisms of tropical thin cirrus clouds, both require detailed documentation and good understanding of thermodynamic structure and variability in the TTL. Observational studies on this topic so far are based primarily on the global radiosonde network, with large data sparse regions, or operational meteorological analyses, with relatively low vertical resolution and attendant biases, or limited satellite data from Global Positioning System Meteorology (GPS/MET) radio occultation measurement, with coarse spatial resolution. In this work, we will use a new global temperature profile data set from the Atmospheric Infrared Sounder (AIRS) on NASA Aqua satellite, with very high vertical (~2 km), horizontal (~50 km) and temporal (twice daily) resolutions, to analyze the thermodynamic structure and variability in the TTL. The AIRS data are available from September 2002 to the present, which also provide a long data record. Following the analysis framework reported in our previous studies [Tian et al., 2006; 2007], we will analyze the horizontal and vertical structures of temperature in the TTL. To highlight the role of tropical deep convection in the TTL thermal structure, we will focus on the intraseasonal time scale (30-90 day), where the Madden-Julian oscillation (aka, intraseasonal oscillation) is the dominant phenomenon. For this purpose, we will use the rainfall data from the Tropical rainfall Measurement Mission (TRMM) to identify MJO events. To help us understand the TTL thermal structure, we will also utilize the dynamical fields from the National Centers for Environmental Prediction (NCEP) reanalysis. If possible, we will also compare our results from AIRS to those from GPS/Constellation Observing System for Meteorology (COSMIC), and/or radiosondes for comparison and validation. This study will advance our understanding of the climatological structure and variability of the TTL and the stratosphere-troposphere exchange. Recorded presentation
Session 5B, General Climate Studies: Observations I
Tuesday, 22 January 2008, 8:30 AM-9:45 AM, 217-218
Next paper