P084-09
Small Lidar for Profiling Water Vapor and Winds from the Mars Surface

Wednesday, 16 December 2020: 07:24
Virtual
James B. Abshire1, Scott David Guzewich2, Daniel Cremons1, Michael D Smith1, Kenji Numata3 and Xiaoli Sun1, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)NASA Goddard Spaceflight Center, Greenbelt, MD, United States, (3)Nasa Goddard Space Flight Center, Laser and Electro-Optics Branch, Greenbelt, MD, United States
Abstract:
The planetary boundary layer (PBL) is the lowest layer of the atmosphere that interacts directly with the surface. Processes within the PBL control the transfer of heat, momentum, dust, water, and other constituents between surface and atmospheric reservoirs. For Mars, understanding these processes is critical for understanding the weather and modern climate, and for being able to test and improve general circulation models.

Since the Mars PBL is difficult to observe from orbit, measurements of it have been mostly limited to those at the surface from landers and rovers. The lack of PBL observations has led to significant gaps of understanding in several key areas. These include diurnal variations of aerosols, water vapor and wind velocities. Since the Mars atmosphere has complex interactions between its dust, water and CO2 cycles, and because these cycles partially drive the wind fields, it is important to measure the profiles of water vapor, aerosols, and winds simultaneously.

Our team is developing a prototype of a small atmospheric lidar for a rover or lander to address these needs. The lidar is being designed to measure vertically-resolved profiles of water vapor by using a single frequency fiber laser. The laser will be tuned onto and off isolated water vapor absorption lines near 1911 nm. The vertical distribution of water vapor will be determined from the on- and off-line backscatter profiles via the differential absorption lidar technique. The same laser is used for measuring aerosol and wind profiles via the Doppler shift in the backscatter. The detect detection lidar’s receiver is polarization sensitive, which allows separating the backscatter of water ice from dust. The lidar emits two beams that are offset 30 deg from zenith and perpendicular to one another in azimuth, allowing resolving the directional wind profiles. Both lidar measurement channels are otherwise identical. The lidar is being designed to have sub-km-scale vertical resolution from the surface to > 15 km altitude, providing measurements several times per hour.

This 3-year development activity is being supported by a 2019 NASA PICASSO award.

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