613 SEMINAR: Prof. FEIQIN XIE, Texas A&M University-Corpus Christi



Dr. Feiqin Xie is an Associate Professor in Atmospheric Science at Texas A&M University-Corpus Christi (TAMU-CC). He obtained his BS and MS (atmospheric physics) from Lanzhou University and Peking University, China in 1998 and 2001, respectively, and the PhD degree (atmospheric science) from the University of Arizona in 2006. After graduation, he spent two-year postdoctoral training at Purdue University and then worked at the NASA Jet Propulsion Laboratory, Caltech, for over 4 years until 2012, when he joined the faculty at TAMU-CC.

613 SEMINAR BY FEIQIN XIE

Planetary Boundary Layer Observations from GNSS Radio Occultation, and the Synergy of Satellite Lidar with Passive Infrared and Microwave Imagers

The planetary boundary layer (PBL), a critical component of the climate system, is the lowest layer of the troposphere, where energy, momentum and masses are exchanged between the Earth’s surface and the free troposphere. Such a thin turbulent layer (averaged about 1~2 km) with frequent cloudiness is extremely difficult to probe from the space. The lack of high-quality global PBL observations has impeded our understanding of the complex physical processes inside the PBL. The 2017 Decadal Survey identified PBL observables as high-priority for the upcoming NASA satellite mission. In this presentation, we first study the cloudy PBL over the subtropical Eastern Pacific Ocean, where low cloud transition from shallow stratocumulus near the continental coast westward to deeper trade cumulus. High vertical-resolution GNSS radio occultation (RO) and CALIPSO lidar along with the high horizontal-resolution passive infrared (MODIS) and microwave (AMSR-E) imagers on Aqua, are used. Given the MODIS cloud-top-temperatures (CTT), the collocated AMSR-E sea surface temperature (SST), and the CALIPSO cloud-top-height (CTH) measurements, the PBL lapse rate climatology is derived, which exhibits significant seasonal and longitudinal variations. The lapse rate is then used to derive a new two-dimensional MODIS CTHs, which are highly consistent with CALIPSO and GNSS RO PBL height (PBLH) observations, and show significant improvement to the MODIS Collection 6 CTH product. Such satellite CTH and PBLH product have also been used to assess the climate model (e.g., CAM5 and CAM5-CLUBB) performance.  We then explore the diurnal variation of the PBLH observed from GNSS RO soundings over the Southern Great Plains. Annual mean diurnal amplitude of approximately 250 m in the terrestrial PBLH was observed, with maxima occurring at around 15:00 local time in both the COSMIC and the co-located radiosondes. Seasonal changes in the PBLH diurnal cycles (100 m - 400 m) were also observed. In the end, several major issues related to GNSS RO measurements, and some exciting opportunity from the existing and upcoming RO constellations (e.g., COSMIC-2 and commercial RO missions) will be discussed.

Bio: Dr. Feiqin Xie is an Associate Professor in Atmospheric Science at Texas A&M University-Corpus Christi (TAMU-CC). He obtained his BS and MS (atmospheric physics) from Lanzhou University and Peking University, China in 1998 and 2001, respectively, and the PhD degree (atmospheric science) from the University of Arizona in 2006. After graduation, he spent two-year postdoctoral training at Purdue University and then worked at the NASA Jet Propulsion Laboratory, Caltech, for over 4 years until 2012, when he joined the faculty at TAMU-CC.

He is a member of the International Radio Occultation Working Group (IROWG), and the NASA MODIS Science Team.  His research focuses on Global Navigation Satellite System (GNSS) radio occultation retrieval from various platforms (e.g., satellite, aircraft, and balloon). His recent projects include the airborne GNSS sensing from stratospheric balloon and the commercial aircraft; the severe storm impact on the upper troposphere and lower stratosphere; and the synergy of GNSS radio occultation (RO) with satellite lidar, passive infrared and microwave imager to study the planetary boundary layer and low clouds.

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613 Seminar Series Coordinators 
Reed.Espinosa@nasa.gov 
Jie.Gong@nasa.gov