Key Points:23 A multi-tiered observational network in California is evaluated during an extreme 24 atmospheric river storm spanning 13-15 February 2019 25 The network validates record precipitable water and detects mesoscale atmospheric 26 processes driving flood, snowfall, and mass wasting events 27 Diverse, high frequency observational networks are valuable investments to aid water 28 resource management and natural hazard mitigation 29 ESSOAr | https://doi.Abstract 30 Observational networks enhance real-time situational awareness for emergency and water 31 resource management during extreme weather events. We present examples of how a diverse, 32 multi-tiered observational network in California provided insights into hydrometeorological 33 processes and impacts during a three-day atmospheric river storm centered on 14 February 2019. 34 This network, which has been developed over the past two decades, aims to improve 35 understanding and mitigation of effects from extreme storms influencing water resources and 36 natural hazards. We combine atmospheric reanalysis output and additional observations to show 37 how the network allows for: 1) the validation of record cool season precipitable water 38 observations over southern California, 2) the identification of phenomena that produce natural 39 hazards and present difficulties for short-term weather forecast models, such as extreme 40 precipitation amounts and snow level variability, 3) the use of soil moisture data to improve 41 hydrologic model forecast skill in northern California's Russian River basin, and 4) the 42 combination of meteorological data with seismic observations to "observe" a large avalanche on 43 Mount Shasta. This case study highlights the value of investments in diverse observational assets 44 and the importance of continued support and synthesis of diverse observations to characterize 45 climatological context and advance understanding of processes modulating extreme weather.46
The corrective optics space telescope axial replacement (COSTAR) configuration contains mechanisms in each science instrument channel that allow for on-orbit correction for image plane focus and for lateral and axial mapping of the Hubble Space Telescope (HST) primary mirror onto the aspheric corrector mirrors. The optical alignment of the COSTAR optics is accomplished in two phases. In Phase I, the mirror bezel tilts and lateral positions are determined through the use of surrogate flat mirrors with the mechanism's positions held at the mid-range of their travel. The Phase I alignment is followed by Phase II interferometric optimization of all five optical channels. At the conclusion of the Phase I alignment, the optics are positioned accurately enough to allow simultaneous correction of most channels on orbit through the use of the mechanism compensation and telescope fme-pointing control. Individual mirror positions and orientations are determined through the use of alignment telescopes, theodolites, alignment lasers, and reference fiducials incorporated into the COSTAR Alignment System (CAS). The proper angles and positions are transferred from the surrogate mirrors to the flight optics, bezels, and shims through use of the alignment transfer fixture (AlT). The flight optics are then installed on the mechanism arms and aligned in decenter and roll. The tolerances on the mirror positions at the conclusion of Phase I alignment are mm in lateral position, 1 mm in axial position, arc sec in azimuthal and elevation angle, and degrees in roll angle.
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Abstract. Based on the large scale transport of dust driven by the winds parallel to the mountains in the Harmattan, Saudi Arabian, and Bodélé Depression dust storms cases, a detailed study of the generation of Kelvin Waves and its possible role in organizing these dust storms and large scale dust transport was accomplished. For this study, observational and numerical model analyses were done in an in depth manner. For this, MERRA reanalysis datasets, WRF simulated high resolution variables, MODIS/Aqua and Terra images, EUMETSAT images, NAAPS aerosol modelling plots, and MERRA-2 dust scattering AOD modelling plots, surface observations, and rawinsonde soundings were analyzed for each of these three case studies. We found there were meso-β scale (horizontal length scale of 20–200 km) adjustment processes resulting in Kelvin waves only in the Harmattan and the Bodélé Depression cases. The Kelvin wave preceded a cold pool accompanying the air behind the large scale cold front instrumental in the major dust storm. We find that this Kelvin wave organized the major dust storm in a narrow zone parallel to the mountains before it expanded upscale (meso-α to synoptic).
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