Reply [to “Comment on ‘Determination of dielectric constant of young sea ice using microwave spectral radiometry’ by K. St. Germain, C. T. Swift, and T. C. Grenfell”]

Germain, Karen M. St.; Swift, C.T.; Grenfell, Thomas C.

doi:10.1029/93jc02189

Cited by 2 publications

(5 citation statements)

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“…The rate of star formation in the central region of this galaxy appears to have remained approximately constant over time. St.-Germain et al (1999) have found a cloud of ∼10 5 M ⊙ of H I located just west of Phoenix, that has a radial velocity of −23 km s −1 , which may be physically associated with this object. Optical radial velocities of stars in Phoenix will be required to confirm this suspicion.…”

Section: The Phoenix Dwarf Galaxymentioning

confidence: 86%

Updated Information on the Local Group

Bergh

2000

PUBL ASTRON SOC PAC

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The present note updates the information published in my recent monograph on \underline{The Galaxies of the Local Group}. Highlights include (1) the addition of the newly discovered Cetus dwarf spheroidal as a certain member of the Local Group, (2) an improved distance for SagDIG, which now places this object very close to the edge of the Local Group zero-velocity surface, (3) more information on the evolutionary histories of some individual Local Group members, and (4) improved distance determinations to, and luminosities for, a number of Local Group members. These data increase the number of certain (or probable) Local Group members to 36. The spatial distribution of these galaxies supports Hubble's claim that the Local Group ``is isolated in the general field.'' Presently available evidence suggests that star formation continued much longer in many dwarf spheroidals than it did in the main body of the Galactic halo. It is suggested that ``young'' globular clusters, such as Ruprecht 106, might have formed in now defunct dwarf spheroidals. Assuming SagDIG, which is the most remote Local Group galaxy, to lie on, or just inside, the zero-velocity surface of the Local Group yields a dynamical age \gtrsim 17.9 \pm 2.7 Gyr.Comment: 19 pages, 1 figure, to be published in the April 2000 issue of PAS

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Section: The Phoenix Dwarf Galaxymentioning

confidence: 86%

Updated Information on the Local Group

Bergh

2000

PUBL ASTRON SOC PAC

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“…In this section, we briefly review the microwave polarization and spectral dependency of emission by ocean and atmosphere for the purpose of describing the physical basis of the SSM/I weather filter. The general theory of microwave emission from the ocean, atmosphere and ice-covered surfaces has been reviewed elsewhere (Gloersen and Barath, 1977; Swift, 1980; Wilheit and Chang, 1980; Gloersen and others, 1992; St. Germain, 1993).…”

Section: Physical Basis Of the Ssm/i Filtermentioning

confidence: 99%

“…For oxygen, water vapor and cloud liquid water, we use the following linear expressions following St. Germain (1993):…”

Section: Physical Basis Of the Ssm/i Filtermentioning

confidence: 99%

“…C is the wavelength-dependent coefficient for oxygen. The expressions for these coefficients have been derived by St. Germain (1993) and are given here for each of the three SSM/I frequencies of interest:…”

Section: Physical Basis Of the Ssm/i Filtermentioning

confidence: 99%

“…Of direct relevance to the problem al hand is the variation of atmospheric water vapor, precipitating and non-precipitating liquid water, near-surface winds and rainfall rates on PR and GR, the two independent variables used in the SSM/I sea-ice algorithm. PR(19)s and GR(37/19)s were generated for a wide range of near-surface winds, cloud liquid water and atmospheric water vapor using the radiative-transfer model described by St. Germain (1993). Similarly, (PR, GR) pairs were generated for a range of rain rates using the Wilheit and Chang (1980) model.…”

Section: Physical Basis Of the Ssm/i Filtermentioning

confidence: 99%

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Reduction of weather effects in the calculation of sea-ice concentration with the DMSP SSM/I

1995

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A problem in mapping the polar sea-ice covers in both hemispheres has been the sporadic false indication of sea ice over the open ocean and at the ice edge. These spurious sea-ice concentrations result from variations in sea-surface roughening by surface winds, atmospheric water vapor and both precipitating and non-precipitating liquid water. This problem was addressed for sea-ice concentrations derived from the Nimbus-7 scanning multi-channel microwave radiometer (SMMR) data through the development of a weather filter based on spectral information from the 18.0 and 37.0 GHz vertical polarization SMMR channels. Application of a similar filter for use with sea-ice concentration maps derived with the special-sensor microwave imager (SSM/I) sensor is less successful. This results from the position of the 19.35 GHz SSM/I channels, which are closer to the center of the 22.2 GHz atmospheric water-vapor line than are the SMMR 18.0 GHz channels. Thus, the SSM/I 19.35 GHz channels are more sensitive to changes in atmospheric water vapor, which results in greater contamination problems. An additional filter has been developed, based on a combination of the 19.35 and 22.2GHz. SSM/I channels. Examples of the effectiveness of the new filter are presented and limitations are discussed.

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Reply [to “Comment on ‘Determination of dielectric constant of young sea ice using microwave spectral radiometry’ by K. St. Germain, C. T. Swift, and T. C. Grenfell”]

Cited by 2 publications

References 2 publications

Updated Information on the Local Group

Updated Information on the Local Group

Reduction of weather effects in the calculation of sea-ice concentration with the DMSP SSM/I

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