Laser emission at 2.8 μm from an Er3+:LiYF4 sample longitudinally pumped with a multiple stripe laser diode array is observed for the first time. The threshold for pulsed laser emission is 33 μJ and for cw laser emission 147 mW. cw laser action in this normally self-terminating laser transition is attributed to a cooperative up-conversion process.

Room-temperature operation of a solid-state laser has been achieved for the first time in the blue region using Pr : YLF. The 0.2% Pr : YLF crystal was longitudinally pumped at 444 nm using a pulsed dye laser. Laser emission was observed at 479 nm and required a pump-energy density of 8 J/cm2 at threshold.

High-resolution polarized absorption and fluorescence spectra of Pr'+ in LiYF4 were measured at temperatures between 10 and 300'K. Energy-level assignments were made assuming electric-dipole transition selection rules for S4 site symmetry. Forty-six energy levels of the 4f ground configuration were established, including 44 in the lowest nine multiplets. Crystal-field parameters were determined that gave a rms deviation of 15.8 cm ' between 41 of the experimental energy levels and calculated values. The parameters were B,o = 488.9, B40 ---1043, B44 --1242, B"= -42, Re B64 --1213, and Im B64 --22.5 cm '. These parameters were used to obtain the remaining energy levels, yielding a complete energy-level scheme for the 4f configuration of Pr'+. The crystal-field parameters for Pr'+ in LiYF4 were compared to those for other ions in this host. A theoretical calculation of line intensities was performed in which the oddfold crystal-field parameters were obtained from a lattice sum. Line intensities were measured and compared with theory.

The National Aeronautics and Space Administration (NASA) Short-term Prediction Research and Transition Center (SPoRT) has been part of a collaborative effort within the National Oceanic and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS) Proving Ground and Risk Reduction (PGRR) Program to develop gridded satellite sounding retrievals for the operational weather forecasting community. The NOAA Unique Combined Atmospheric Processing System (NUCAPS) retrieves vertical profiles of temperature, water vapor, trace gases, and cloud properties derived from infrared and microwave sounder measurements. A new, optimized method for deriving NUCAPS level 2 horizontally and vertically gridded products is described here. This work represents the development of approaches to better synthesize remote sensing observations that ultimately increase the availability and usability of NUCAPS observations. This approach, known as “Gridded NUCAPS”, was developed to more effectively visualize NUCAPS observations to aid in the quick identification of thermodynamic spatial gradients. Gridded NUCAPS development was based on operations-to-research feedback and is now part of the operational National Weather Service display system. In this paper, we discuss how Gridded NUCAPS was designed, how relevant atmospheric fields are derived, its operational application in pre-convective weather forecasting, and several emerging applications that expand the utility of NUCAPS for monitoring phenomena such as fire weather, the Saharan Air Layer, and stratospheric air intrusions.

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