title: Far-infrared spectroscopy of the troposphere: instrument description and calibration performance.
abstract: The far-infrared spectroscopy of the troposphere (FIRST) instrument is a Fourier transform spectrometer developed to measure the Earth's thermal emission spectrum with a particular emphasis on far-infrared (far-IR) wavelengths greater than 15 μm. FIRST was developed under NASA's Instrument Incubator Program to demonstrate technology for providing measurements from 10 to 100 μm (1000 to 100 cm(-1)) on a single focal plane with a spectral resolution finer than 1 cm(-1). Presently no spectrometers in orbit are capable of directly observing the Earth's far-IR spectrum. This fact, coupled with the fundamental importance of the far-IR to Earth's climate system, provided the impetus for the development of FIRST. In this paper the FIRST instrument is described and results of a detailed absolute laboratory calibration are presented. Specific channels in FIRST are shown to be accurate in the far-IR to better than 0.3 K at 270 K scene temperature, 0.5 K at 247 K, and 1 K at 225 K.
authors: Space Dynamics Laboratory, 1695 North Research Park Way, North Logan, UT 84341, USA.
authors: Harri
authors: H
authors: Latvakoski
authors: Martin G
authors: MG
authors: Mlynczak
authors: David G
authors: DG
authors: Johnson
authors: Richard P
authors: RP
authors: Cageao
authors: David P
authors: DP
authors: Kratz
authors: Kendall
authors: K
authors: Johnson