4800 Oak grove Drive
In the past 15 years, Dejian has been serving in the international science-technology communities (atmospheric composition, instrumentation, algorithm, air quality, climate, molecular spectroscopy) and suborbital/orbital missions. Dejian's specialty is developing new remote sensing instruments and retrieval algorithms for profiling the atmospheric composition, with focus on the near surface layer (0-2 km) and the middle-upper troposphere. New global measurements in these two altitude regions are needed to address a suite of scientific objectives ranked as "MOST IMPORTANT" in the 2017 Earth Sciences Decadal Survey (ESDS), since the gaseous and aerosol pollutants in the near surface layer affect the health and economic prosperity of billions of people, and the middle-upper tropospheric constituents drive the regional-global climate changes.
Dejian has been leading the HiMAP instrument concept development since 2018. HiMAP will enable the new global measurement capability of quantifying the gaseous and aerosol pollutants in the near surface layer, via combining multiple angular, spectrally resolved, polarimetric measurements within a compact form factor (~6U). In 2019, he was funded by NASA ESTO to develop "A broadband metasurface for high spectral resolution, imaging spectropolarimetry" - HiMAP's key technology component. Dejian originated a full-physics atmospheric isoprene retrieval algorithm in 2014 when the laboratory isoprene cross sections in the thermal infrared (TIR) were first reported in an international molecular spectroscopy conference. Dejian and his team surveyed observations from the existing satellite TIR sensors (TES, CrIS, AIRS, IASI) and demonstrated that isoprene can be directly quantified from CrIS measurements to advance our understanding of the atmospheric chemistry and climate, since isoprene is a key species driving the atmospheric oxidizing capability. Dejian has also been serving in the remote sensing algorithm communities and satellite missions. His contributions include successful implementation and application of a retrieval algorithm, namely, MUSES, which enables the unique, joint NASA-NOAA-ESA multiple-spectra, multiple-species and multiple-satellite retrievals. MUSES is known as an algorithm tool that enhances near-surface sensitivity and extends the multiple-decade continuity of NASA atmospheric ozone and carbon monoxide profile data, thus supporting the new science of air quality and climate research.