The future mission of the Earth Science Lidar

January 20, 2017 · Posted in Uncategorised 

1 Ice Sheet, Cloud and Land Altitude Monitoring Satellite-2 Mission (ICESat-2) ICESat-2 is the ICESat follow-up mission. ICESat was launched in January 2003 and ended in February 2010. ICESat-2 will provide high-quality terrain measurement data to assess the changes in ice volume, decisive ice melting to sea-level rise. ICESat-2 on the load name for the Advanced Terrain Measurement Laser Altitude System (AdvancedTopographicLaserAltimeterSystem best cnc machines, ATLAS). The original ATLAS vision is an egg-beam laser height system that follows the GLAS concept with low repetition (50 Hz), high energy (pulse energy 50 mJ), and short pulse width (about 6 ns). In mid-2009, ATLAS was re-envisioned. At the moment the idea of ​​using non-scanning 6 beam system, the beam arrangement is 3 × 2, using micro-pulse photon counting system, as shown in Figure 1. Figure 1 (a) NASES second-generation Earth orbit multi-beam laser altimeter ICESat-2 shows the attempt; (b) The laser uses high repetition frequency (10kHz) welding gantry, medium energy (single pulse energy about 900μJ), short pulse width (<1.5ns). Hamamatsu Model 7600-16M photomultiplier was used as the detector. Laser wavelength 1064nm frequency multiplier of 532nm, the reason is the lack of space for the use of long-lived near-infrared single photon detector. Figure 2 (left) space measurement point of view; (on the right) using the two HITRAN2004 calculated near the 1570nm wavelength near CO2 transmittance results; (left) at the moment the choice of 1572 metal sheet punching machine.33nmCO2 receive line and wavelength sampling strategy; Weighted function of calculation 3.2 Automatic Monitoring of CO2 Emissions at Night, Day and Season (ASCENDS) ASCENDS intends to be the first space-based laser spectroscopy instrument that can be thought of as weather and hydrography to monitor changes in aerosols and clouds, and to monitor changes in sea-color for open-ocean biogeochemistry.

 

ASCENDS using laser absorption spectroscopy to measure the global atmosphere of carbon dioxide spatial distribution of precision to 1 ~ 2ppm, measuring global land and sea carbon dioxide source and sink spatial resolution of 1 degree, the data update rate once a month, can supply On the continuous measurement of the sea without clouds, in the low sun angle and night can do. GSC (GoddardSpaceFlightCenter) uses a pulsed lidar as a candidate for ASCENDS, as shown in Figure 3. The scheme uses a parametric erbium-doped fiber amplifier to amplify the 1.57μm spectral range of the near-far wavelength, which is used to measure the atmospheric carbon dioxide. The accuracy of the initial path measurement is less than 1%. Using a dual-band laser pulse laser absorption spectrometer and differential path to receive laser radar technology. Figure 3 space laser radar performance and 500km orbital altitude radar mold mounted map 3.3 LIDAR Profiles Description of the Measurement Mission (LIST) LIST intends to complete the measurement requirements of jade into the cage cover, life of 3 years cnc punch, 400km orbital height, 5km imaging banner width, the basic rationale shown in Figure 4. 3.4 Earth Gravity Field Measurements and Weather Attempts (GRACE-FO and GRACE-2) GRACE-2 system is estimated to launch in 2025, the system uses a laser ranging system to get a higher accuracy. The GRACE-FO system was estimated to be launched in 2016 to verify the feasibility of the laser ranging system used in the GRACE-2 system. The performance objectives of single-frequency lasers in GRACE-FO are shown in Table 2.

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