Sensors
SAPHIR Overview

SAPHIR is a sounding instrument with 6 channels near the absorption band of water vapor at 183 Ghz. These channels provide relatively narrow weighting functions from the surface to about 10 km, allowing retrieving water vapor profiles in the cloud free troposphere. The scanning is cross-track, up to an incidence angle of 50°. The resolution at nadir is of 10 km.

SAPHIR channel specification

Channel	Central Frequency (GHz)	Bandwidth (MHz)	NE∆T	Polarization	Interchannel calibration
S1	183.31±0.20	200	2.35 K	H	0.5K
S2	183.31±1.10	350	1.45 K	H	0.5K
S3	183.31±2.80	500	1.36 K	H	0.5K
S4	183.31±4.20	700	1.38 K	H	0.5K
S5	183.31±6.80	1200	1.03 K	H	0.5K
S6	183.31±11.0	200	1.10 K	H	0.5K

---

Scan pattern of the SAPHIR instrument (image credit: CNES)

---

The 6 channels of SAPHIR positioned versus the water vapour absorption line at 183.31 Ghz

---

Source: MEGHA-TROPIQUES Home

Source: MEGHA-TROPIQUES @ eoPortal