SCIENTIFIC RESULTS 



189 



A service of iceberg' forecast in<>\ covei-ino- the spriiio- season for 

 the Avesterii North Athintic based upon the above correlations, was 

 instituted in 11>"2() and has been continued through 1929. Forecasts 

 coini)are(l with actual records have been as follows: 



ntM-ss 

 345 

 390 

 515 



ll)l!(i, lielow normal-. 



1927. normal 



1928. al)ove normal.^ 



1929. below norniaL 



1930. above norma 1_. 



Berss 

 150 

 386 

 500 

 350 

 520 



1926. bt'ldw iiDrmul 



1927. normal 



1928. al)ove normal 



1929 (estimated''), far above 



normal 1, 300 



193(K above normal 475 



A comparison of tlie actual nnniber of icebergs with those fore- 

 casted a month prior to the inauguration of the berg season, shows 

 four successes out of five predictions. We are able, apparently, to 

 predict cpiite accurately the smaller deviations from normal from 

 year to year, but the occasional great iceberg seasons such as 1909, 

 1912, and 1929 come without meteorological warning. As onr knowl- 

 edge of ice, meteorology, and oceanogra})hy of polar conditions 

 increases we have good cause to expect improvements in iceberg 

 forecasting. 



ANNUAL AMOUNTS OF GLACIAL ICE AND SEA ICE 



Considerable (juantitative data have been compiled by comparing 

 the relatives volumes of glacial ice and of sea ice discharged into the 

 northwestern Xorth Atlantic annually. The material discharged 

 from the iceberg fjords, set forth in tlie foregoing discussion (p. 95), 

 at 4.G cubic (nautical) miles (29-^ kilometers), more or less is estimated 

 to amount to 70 per cent of the annual output. The total wastage for 

 the entire coast of west Greenland is something like 7 to 10 cubic 

 miles (42" to 63'^ kilometers). The American shores are believed to 

 contribute about 0.3 cubic mile (1.9-'" kilometers). 



The total area of sea ice which is fed into the northwestern North 

 Atlantic during any one season, and which melts annually, may be 

 calculated quite closely from a map of these regions (see fig. 121, p. 

 200). ni)on Avhich is ])lotted the ice and water temperature records of 

 the northwestern North Atlantic. The shelf area included between the 

 coast line on one side and the 200-fathom depth contour on the other 

 approximates the bounds of melting sea ice. The area in which we 

 are particularly interested is equal to 4G7,300 square miles, and on 

 Figure 121 it is the shaded portion bounded by the full black line. 

 Occupying the same general inclosure but spread out somewhat 

 farther on its outer side, to and including the dotted line, lies the 

 melting area. The fact that sea ice remains on the whole within the 



^ The single failure occunvd in the year 1929. The critical months for Davis Strait — - 

 Deceml)er to March — showed December pressure normal, hut .January was made notable 

 hy one of the greatest excesses of atmospheric pressure over Iceland ever recorded. 

 Europe, in coiise(|uence. suffered a severely cold winter and Davis Strait one of the 

 warmest Decembers on record. This system of winds distinctly forbade the southward 

 transportation of ice. February witnessed a " high " over the Canadian Maritime Prov- 

 inces and a "low"' southeast of Cape Farewell, thus initiating a northwesterly air stream 

 which proved as favoralilo for the invasion of ice as conditions the previous "month were 

 unfavoiable. The fact, however, that December is given twice the weight of .Janu- 

 ary in the equation employed makes the former much o\itvveigh the latter in the forecast. 

 March was only niodi-rately favorjible to ice importation .md therefore it failed m'aterially 

 to effect the tinal iiiedietion of a berg year below normal. The presence of over L.SOb 

 icebergs snuth of Newfuundlatid in 1929 can not, therefore, be explained by meteorological 

 factors, but iiuist liave resulted from some other cause, iierhaps one of those listed on 

 J>. 188. 



