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Abstract The JWST Disk Infrared Spectral Chemistry Survey (JDISCS) aims to understand the evolution of the chemistry of inner protoplanetary disks using the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST). With a growing sample of >30 disks, the survey implements a custom method to calibrate the MIRI Medium Resolution Spectrometer (MRS) to contrasts of better than 1:300 across its 4.9–28μm spectral range. This is achieved using observations of Themis family asteroids as precise empirical reference sources. The high spectral contrast enables precise retrievals of physical parameters, searches for rare molecular species and isotopologues, and constraints on the inventories of carbon- and nitrogen-bearing species. JDISCS also offers significant improvements to the MRS wavelength and resolving power calibration. We describe the JDISCS calibrated data and demonstrate their quality using observations of the disk around the solar-mass young star FZ Tau. The FZ Tau MIRI spectrum is dominated by strong emission from warm water vapor. We show that the water and CO line emission originates from the disk surface and traces a range of gas temperatures of ∼500–1500 K. We retrieve parameters for the observed CO and H₂O lines and show that they are consistent with a radial distribution represented by two temperature components. A high water abundance ofn(H₂O) ∼ 10⁻⁴fills the disk surface at least out to the 350 K isotherm at 1.5 au. We search the FZ Tau environs for extended emission, detecting a large (radius of ∼300 au) ring of emission from H₂gas surrounding FZ Tau, and discuss its origin. 

Abstract We present velocity-resolved Stratospheric Observatory for Infrared Astronomy (SOFIA)/upgrade German REceiver for Astronomy at Terahertz Frequencies observations of [O i ] and [C ii ] lines toward a Class I protostar, L1551 IRS 5, and its outflows. The SOFIA observations detect [O i ] emission toward only the protostar and [C ii ] emission toward the protostar and the redshifted outflow. The [O i ] emission has a width of ∼100 km s −1 only in the blueshifted velocity, suggesting an origin in shocked gas. The [C ii ] lines are narrow, consistent with an origin in a photodissociation region. Differential dust extinction from the envelope due to the inclination of the outflows is the most likely cause of the missing redshifted [O i ] emission. Fitting the [O i ] line profile with two Gaussian components, we find one component at the source velocity with a width of ∼20 km s −1 and another extremely broad component at −30 km s −1 with a width of 87.5 km s −1 , the latter of which has not been seen in L1551 IRS 5. The kinematics of these two components resemble cavity shocks in molecular outflows and spot shocks in jets. Radiative transfer calculations of the [O i ], high- J CO, and H 2 O lines in the cavity shocks indicate that [O i ] dominates the oxygen budget, making up more than 70% of the total gaseous oxygen abundance and suggesting [O]/[H] of ∼1.5 × 10 −4 . Attributing the extremely broad [O i ] component to atomic winds, we estimate an intrinsic mass-loss rate of (1.3 ± 0.8) × 10 −6 M ⊙ yr −1 . The intrinsic mass-loss rates derived from low- J CO, [O i ], and H i are similar, supporting the model of momentum-conserving outflows, where the atomic wind carries most momentum and drives the molecular outflows.