CALIPSO PAYLOAD

The CALIPSO payload consists of three co-aligned nadir-viewing instruments:

• the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)
• the Imaging Infrared Radiometer (IIR)
• the Wide Field Camera (WFC)

These instruments are designed to operate autonomously and continuously, although the WFC acquires data only under daylight conditions. Science Data are downlinked using an X-band transmitter system which is part of the payload.

For more information on CALIPSO's payload, visit these journal articles:

Winker, D. M., W. H. Hunt, and M. J. McGill, 2007: Initial performance assessment of CALIOP, Geophys. Res. Lett., 34, L19803, doi:10.1029/2007GL030135. [Download Paper (PDF)]

Winker, D. M., W. H. Hunt, and C. A. Hostetler, 2004: Status and Performance
of the CALIOP Lidar, Proc. SPIE vol 5575, 8-15. [Download Paper (PDF)]

The physical layout of the payload is shown below, with key instrument characteristics listed in the following table.

CALIOP is a two-wavelength polarization-sensitive lidar that provides high-resolution vertical profiles of aerosols and clouds. Examples of this measurement capability can be found at the LITE and ICESAT homepages.

CALIOP utilizes three receiver channels: one measuring the 1064 nm backscatter intensity and two channels measuring orthogonally polarized components of the 532 nm backscattered signal. Dual 14-bit digitizers on each channel provide an effective 22-bit dynamic range. The receiver telescope is 1 meter in diameter. A redundant laser transmitter is included in the payload.

An active boresight system is employed to maintain co-alignment between the transmitter and the receiver. Ball Aerospace Corporation, developed the instrument.

The WFC is a modified version of the commercial off-the-shelf Ball Aerosopace CT-633 star tracker camera. It is a fixed, nadir-viewing imager with a single spectral channel covering the 620-670 nm region, selected to match band 1 of the MODIS (MODerate resolution Imaging Spectroradiometer) instrument on Aqua.

A three-channel IIR is provided by CNES with algorithm development performed by the Institute Pierre Simon Laplace (IPSL) in Paris.

The IIR a nadir-viewing, non-scanning imager having a 64 km by 64 km swath with a pixel size of 1 km. The CALIOP beam is nominally aligned with the center of the IIR image.

The instrument uses a single microbolometer detecter array, with a rotating filter wheel providing measurements at three channels in the thermal infrared window region at 8.7 mm, 10.5 mm, and 12.0 mm. These wavelengths were selected to optimize joint CALIOP/IIR retrievals of cirrus cloud emissivity and particle size.

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