Analysis of a random modulation single photon counting differential absorption lidar system for space-borne atmospheric CO2 sensing

摘要

The ability to observe the Earth’s carbon cycles from space provides scientists\udan important tool to analyze climate change. Current proposed systems are mainly based on\udpulsed integrated path di�erential absorption lidar, in which two high energy pulses at di�erent\udwavelengths interrogate the atmosphere sequentially for its transmission properties and are\udback-scattered by the ground. In this work an alternative approach based on random modulation\udsingle photon counting is proposed and analyzed; this system can take advantage of a less power\uddemanding semiconductor laser in intensity modulated continuous wave operation, benefiting\udfrom a better e�ciency, reliability and radiation hardness. Our approach is validated via numerical\udsimulations considering current technological readiness, demonstrating its potential\udto obtain a 1.5 ppm retrieval precision for 50 km averaging with 2.5 W average power in a\udspace-borne scenario. A major limiting factor is the ambient shot noise, if ultra-narrow band\udfiltering technology could be applied, 0.5 ppm retrieval precision would be attainable.