Snow Accumulation Studies on the Thule Peninsula, Greenland

Mock, S. J.

doi:10.1017/s0022143000020402

Cited by 27 publications

(11 citation statements)

References 13 publications

(5 reference statements)

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“…Virtually all air masses at ground level come to Camp Century from the ESE sector, which is the virgin interior. The present accumulation rate, after vapor ablation, is 35 gms H 2 0/cm 2 yr (MOCK, 1968b;CROZAZ et al, 1966;CROZAZ and LANGWAY, 1966). Accumulation increase-; to the SE.…”

Section: Sample Collectionmentioning

confidence: 78%

Chemical concentrations of pollutant lead aerosols, terrestrial dusts and sea salts in Greenland and Antarctic snow strata

Murozumi

Chow

Patterson

1969

Geochimica et Cosmochimica Acta

761

234

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Section: Sample Collectionmentioning

confidence: 78%

Chemical concentrations of pollutant lead aerosols, terrestrial dusts and sea salts in Greenland and Antarctic snow strata

Murozumi

Chow

Patterson

1969

Geochimica et Cosmochimica Acta

761

234

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“…16) Using A values from surface measurements (Langway, 1967, p. 94-95; measurements used; Mock's Camp Century value of 3 I 8 kg/m2 from 1955-62 firn stratigraphy and Langway's Site 2 value of 423 kg/m2 from 1954-57 firn stratigraphy indicate a 33 % difference. Such comparison is complicated by the different accumulation years represented by the various measurements, and the microwave observations, and also by significant accumulation gradients (Mock, 1968) over the surface within a resolution element of the microwave observations. Nevertheless, the accumulation value measured at the surface at Site 2 and that which is estimated from the observed emissivity agree well within the uncertainties of the methods.…”

Section: K = Exp [ -E Jrtrn] Jexp [ -Ejrtrn O] mentioning

confidence: 99%

Microwave Emissivity and Accumulation Rate of Polar Firn

1977

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ABSTRACT. Radiative transfer theory is formul a ted to permit a m eaningful d efiniti o n o f emiss ivity fo r bulk emitting media such as snow. The emissivity in the Rayleigh-J ea ns approxima tion is then the mi crowave brightness temperature T B divided by an effective physica l te mpe ra ture ( T ) . The ( T ) is an average of the physical temperature, T (z), weighted by a radia tive tra nsfer fun ctio n f (z ). Similarly, CL) TB = ff (z )e(z) T (z) d z whe re e(z ) is the local emittance. An a pproxima te f (z) is used to determin e o a na ly ti cally the effects of va rious absorption coeffi cients, of sca tte ring coeffi cients that va ry with d epth, a nd of the seasonal variatio n o f T (z) . It is shown tha t a mea n emiss ivity, whi ch is equal to the mean a nnual T B divided by the mean annua l surface tempe ra ture Till , is a useful qua ntity fo r comparing theory and observatio ns. Snow-crystal size measurem ents, r (z), a t seve n loca tio ns in Greenland and Antarctica are used to d e termine the Mi e/ Rayle igh scattering coeffi cient ys(z) a nd to calcula te the m ean emissivities.The observed mean emiss ivities a re determined by a TB, whi ch is the a verage of 12 monthly (1.55 c m ) microwave observa tio ns, a nd the Tm m easured a t the sa m e locations. The calculated emiss ivities are a bout one-half of the obser ved values. The assumption tha t each snow crysta l is a n independent a nd equa lly effec tive scatterer , a nd the use of a n a pproxima tion to f (z), te nd to over-estimate the effe ct of sca ttering. Therefore, a p a r a m e ter multiplying y s(z) is used . T h e e missivities calculated with a single value of this empirical para m e te r for all seven loca tions agree well with the observed emissivities, showing that the microwave emissivity variations of dry pola r firn can be ch a r acterized as a fun c tion of the crys tal sizes . One optical d epth corres po nds to a typi cal firn d epth of 5 m , but significant radiatio n em a na tes from up to 30 m . Since r (z) d ep e nds on the snow a ccumula tion rate A a nd T rn, the sensitiv ity of the emissivity to changes in Tm or A are es tima ted using this semi-empirical theory. The results show tha t a one d egree cha nge or un certa inty in T m is a pproximately equivalent to a 10 % ch a nge in A, and tha t such a change will a ffect the emissivity by 0.003 to 0.0 14 or the Tn by a bout 0.6 K to 3 K , depending o n the location . T (z ).On montre qu 'une e missivite moyenne, qui es t ega le a la m oye nne a nnuelle T B divisee par le tempe rature moyenne annuelle de surface Trn , est une qua ntite utilisable pour co mpa rer les theories et les observations. L es m esures des dimensio ns d es cristaux d e neige, r (z) en sept points du G roenla nd e t d e l' Anta rctique sont utilisees pour d etermine r le coeffi cient y s( z) d e dispersion d e Mie/R ayleigh e t p our calculer les emissivites moyennes. L es e miss ivites moyenn es o bservees sont d e te rminees pa r une va leur TB qui es t la moyenn e sur 12 observa tion...

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“…In general terms, snowmelt and icemelt on temperate glaciers form part of the ablation process. The meltwater, Benson (1961) or Mock (1968). The green represents icecovered areas, and the concentric circle and dot symbol represents ice-core sites.…”

Section: Annual and Summer Balancementioning

confidence: 99%