MAMS

MAMS

Points of Contact:

Anthony Guillory and Gary Jedlovec

Global Hydrology and Climate Center

NASA/ Marshal Space Flight Center/ Code: SD60

Huntsville, Alabame 35805

Office Telephone: (256) 961-7894, (256) 961-7964

FAX: (256) 961-7723

E-mail: anthony.guillory@msfc.nasa.gov, gary.jedlovec@msfc.nasa.gov

Brief Instrument Description of the
Multispectral Atmospheric Mapping Sensor (MAMS)

The MAMS is a multispectral scanner which measures reflected radiation from the Earth's surface and clouds in 8 visible/near infrared channels and thermal emission from the surface, clouds, and atmospheric constituents (primarily water vapor) if four infrared bands. The scanner views a 37 kilometer wide scene of the Earth from the ER2 altitude of about 20 kilometers. Each MAMS footprint (individual field of view) has a horizontal resolution of 100 meters at nadir. Since the ER2 travels at about 208 meters per second, a swath of MAMS data 37 by 740 kilometers is collected every hour. The nominal duration of an ER2 flight is 6 hours (maximum of about 7 hours).

>A number of geophysical parameters can be derived from the MAMS data. The resolution of each product varies because of the desired accuracy of each parameter. The table below lists the parameters which can be derived from MAMS for CAMEX research. Precipitable water and skin temperature (land or sea surface) are derived from with a physical split window algorithm (Jedlovec 1987; Guillory et al 1993; Suggs and Jedlovec 1986). The accuracy of precipitable ranges between 2 -5 mm root mean square error based on the MAMS calibration, quality of the first guess, the desired spatial resolution, and the sounding environment (poor performance occurs where temperature inversions exist). Sea surface temperature is retrieved quite accurately and not subject to the temperature inversion problem. Varying surface emissivity over land influences the quality of the land surface temperature retrieval. Upper-level humidity is retrieved with an empirical method similar to Soden and Bretherton (1993). Accuracy varies with MAMS calibration and the locally generated retrieval coefficients. Clouds can be detected quite well with the multispectral channels of MAMS (even thin cirrus). Cloud top temperature and height assignment varies with MAMS absolute calibration and cloud emissivity. Absolute calibration degrades at cold temperatures and therefore cloud top information approaches worst values for the tallest (coldest clouds).

References

1.     Guillory, A.R., G.J. Jedlovec, and H.E. Fuelberg, 1993: A Technique for Deriving Column-Integrated Water Content Using VAS Split-Window Data. J. Appl. Meteor. 32, 1226-1241.

2.        Jedlovec, G.J. , 1987: Determination of atmospheric moisture structure from high resolution MAMS radiance data., Ph.D. dissertation. Ph.D. Degree. The University of Wisconsin-Madison, University Microfilm International, Ann Arbor, MI. 187.

3.     Soden, B.J. and F.P. Bretherton, 1993: Upper tropospheric relative humidity from the GOES 6.7um channel: Method and climatology for July 1987. J. Geophys. Res. 98, 16669-16688.

4.     Suggs, R.J. and G.J. Jedlovec, 1996: Evaluation of a split window technique for the retrieval of geophysical parameters from GOES. In preparation for J. Appl. Meteor.

MAMS CAMEX Derived Parameters and Their Accuracy

 

Parameter	Resolution	Coverage	Accuracy
Total Precipitable Water	250 - 1000 m	over entire image	2 - 5 mm rms
Land Surface Temperature    0.5 - 0.6 K (absolute)	100 - 300 m	over entire image	0.1 - 1.0 K (relative)
Sea Surface Temperature	100 - 300 m	over entire image	0.1 K (relative)   0.1 - 1.0 K (absolute)
Upper-Level Humidity   (in weighting function layer)	100 - 300 m	over entire image	1 - 2% (relative)   5 - 10 (absolute)
Cloud Detection	100 - 200 m	over entire image	99% efficiency
Cloud Mean Top Temperature	100 - 200 m	where cloud present	0.5 K (relative)   0.5 - 6.0 K (absolute)
Cloud Mean Height (Pressure)	100 - 200 m	where cloud present	50 mb (relative)   50 - 200 mb (absolute)