NPOESS Conical Scanning Microwave Imager Sounder CMIS Overview

NPOESS Conical Scanning Microwave Imager/ Sounder (CMIS) Overview David Kunkee June 23, 2002

Background • NPOESS Conical Scanning Microwave Imager Sounder (CMIS) – Continues and Improves on the Missions of SSM/I, SSMIS – Next Generation Polar-orbiting Operational Radiometer • MISSION: – Provide a variety of data-products: 22 Environmental Data Records (EDRs) – An integral part of the NPOESS constellation • Design – CMIS design was optimized with respect to an Integrated Requirements Prioritization List (IRPL) and risk

CMIS Data Products and Design Priorities

CMIS Design Overview • CMIS primary design drivers: – Cat I EDRs, Cat II EDRs and Cost • Current CMIS Design – 77 Channels: 37 channels with 40 FFT channels – Two main reflectors: • Low Frequencies (LF): 2. 2 m • High Frequencies (HF): 0. 5 X 0. 7 m – Two feedhorn clusters • LF cluster: 12 feedhorns, 6 – 89 GHz • HF cluster: 4 feedhorns, 166 and 183 GHz – >0. 9 reliability after 7 years on orbit + 8 years storage • Substantial redundancy – 257 kg mass; 280 kb/s data rate; 291 W orbital average power

Conical-Scanning Microwave Imager/Sounder

CMIS Channel Set * *Polarizations: V=Vertical, H=Horizontal, P=+45 degrees, M =– 45 degrees, L=Left-hand Circular, R=Right-hand Circular

CMIS Scan Geometry

CMIS Footprint Arrangement

Antenna Beam Sampling • Co-registration of footprints – Requires up to 9 scan rotations – High Frequency observations are offset in elevation to overlay Low Frequency antenna beam footprints • Antenna Beam Sampling – CMIS Provides Nyquist sampling for all channels along scan – Nyquist sampling achieved cross-scan beyond ~20 degrees of the center of scan – Head-to-toe (contiguous) sampling along track

CMIS Data Products and Algorithms • Atmospheric and Environmental Research (AER) – All EDRs (and intermediate data products) except Ocean EDRs • Remote Sensing Systems (RSS) – Ocean EDRs • Microwave Operational Algorithm Team (MOAT) – Government/University advisory board to CMIS – Shares latest science and techniques with AER/RSS • Sea Surface Wind Direction: – 10, 18, 37 GHz (V, H) 18, 37 GHz (– 45, +45) 10, 18 GHz (LH, RH) • Temperature Sounding: – 60 GHz (9 channels from 50. 3 to 59. 94 GHz, V-pol) – 40 FFT channels centered on 7+ O 2 line (60. 434776 GHz)

CMIS EDR Algorithms • AER uses a unified retrieval approach – All available radiometric & auxiliary/ancillary data supplied to a physical retrieval scheme • Optimizes solution based on the internal model – Retrieval produces vertical moisture profile and vertical temperature profile • Output generated at predetermined altitudes • Includes Surface Temperature & Emissivity • Output is supplied algorithms that produce remaining non-ocean EDRs

CMIS EDR Algorithms (Cont’d) • Ocean EDRs Remote Sensing Systems – Based on CMIS calibrated brightness temperatures – Ocean EDRs are supplied as input to the unified retrieval – Sea-Surface Wind Direction (SSWD) is a key development of CMIS

Heritage Radiometers • Several sensors qualify as “heritage” – SSM/I (special-sensor, microwave imager) • Only Operational Conical-Scanning microwave imager on orbit – SSMIS (microwave imager/sounder) • Not yet launched – scheduled for October 2002 • Includes temperature and moisture sounding channels • Other ‘pathfinders’ – AMSR-E • Includes imaging channels 6 – 89 GHz 1. 6 m reflector – WINDSat • Sea surface wind direction from polarimetric microwave measurements • Full polarimetric capability at 10, 18 and 37 GHz • Risk reduction for CMIS

SSM/I Scan Geometry J. L Hollinger, J. L. Peirce and G. A. Poe, “SSM/I Instrument Evaluation”, IEEE Trans. Geosci. Remote Sensing, 28(5), Sept 1990

SSM/I and CMIS Imaging Channels SSM/I CMIS Imaging

Conical Scanning Radiometers (I) L-R: TMI CMIS SSM/I

Conical Scanning Radiometers (II) Special Sensor Microwave Imager Sounder (SSMIS) Advanced Microwave Scanning Radiometer (EOS) (AMSR-E)

Summary • CMIS offers: – New operational data products • Sea Surface Wind Direction • Soil Moisture • Cloud Base Height – Quantifiable improvements in heritage data products • Spatial Resolution • Measurement Range