cause the elimination of one of the tenns. For 

 example, in order to solve for F, a berg must be 

 located in water which is 0° C. or less. This all 

 but eUminates the melting of the underwater 

 portion and allows the dropping of the tenn 

 containing R thus allowing the solution for F. 

 Accurate mass measurements with time must be 

 made in order to detennine AM,. Conversely, 

 a cold air and warm water environment will allow 

 the determination of R with the eUmination of 

 the F term. 



The known density value will allow computa- 

 tion of total mass and mass change from the 

 measurement of the above the water volume, 

 therefore, only these measurements need be made. 

 By studying many bergs in various environments 

 the values of F and R can be detennined and the 

 table shown above can be completed. The 

 figures for F and R will become more reliable as 

 more bergs are observed. 



After F and R are characterized, the equation 

 for deterioration time, equation 10, can be modi- 

 fied for practical application. This is done by 

 substituting the total mass (M,) of the berg that 

 must deteriorate above the water (.1 M!) and 

 below the water (.9 M,) for the A/Wi and AA/2 

 values respectively. Further simplication of 

 terms of equation (10) gives: 



thus, 



^ AM, , „ .9M, 

 G=^r- and S=-^- 



D time=0.024 [g^ + ~'] 



where the 6 and S terms can be precomputed 

 and a table prepared similar to that above for F 

 and A'. Because the table is already broken 

 down for size, only the estimation or rather the 

 designation of the mass values of the small, 

 medium, and large bergs must be made. These 

 characteristic values for mass are best left to be 

 designated from the size measurements obtained 

 for the determination of R and f\ The basic 

 approach is to determine the values of R and F 

 for many bergs and then attempt to categorize 

 these bergs for mass and size into the types and 

 groups shown above. A more sophisticated 

 breakdown could be employed depending on the 

 direction dictated by the obtained data. 



This approach is at best only a start. A better 

 breakdown for size and shape may evolve as the 

 study progresses. A more detailed deterioration 



expression cannot be used because of the limitation 

 requirement of minimal data gathering for a par- 

 ticular berg. Thus, this system is presented which 

 would allow deterioration predictions to be made 

 based on data collected by either ships or aircraft 

 without the involvement of scientific personnel. 



Data Collection 



During the interval between the first and second 

 current surveys of Ice Patrol 1965, an iceberg was 

 studied for the drift and deterioration rate. Many 

 environmental measurements were made, along 

 with actual size measurements of the berg in an 

 effort to initiate a deterioration study. 



Environmental parameters were measured on 

 an hourly basis and are presented in figures IC 

 through 5C. They include: air temperature, sea 

 surface temperature, barometric pressure, wind 

 direction, wind velocity, wave height, wave direc- 

 tion, and incident solar radiation. The solar 

 radiation was measured continuously and recorded 

 by an Epply pyrheliometer. 



Several oceanographic casts were made in the 

 vicinity of the berg during the study period fo 

 27 April to 6 May 1965. The stations occupied 

 can be found in the appendix and include stations 

 9307 to 9312. 



Size measurements of the berg were accom- 

 pHshed daily by a photographic mapping tech- 

 nique. A series of photographs were taken around 

 the berg at approximately 30° intervals of arc. 

 This provided photographs covering all sides of 

 the berg. Overlapping pictures of the starting 

 point were made at the completion of the round of 

 photographs and used to estimate the amount of 

 berg rotation during the photographing process. 

 With this knowledge, and assuming uniform rota- 

 tion, the pictures obtained at the recorded intervals 

 could be adjusted to their true angular aspect. 

 This process is displayed graphically in figure 7C. 

 A sample series of photographs are shown in 

 figures 8C and 9C. 



The subject berg had a surface configuration 

 which was characteristic enough to detect the 

 rotation. Provisions were made however to put 

 a dye spot on the berg (figure IOC) to provide a 

 benchmark to detect this motion. For this par- 

 ticular berg, the dye mark was utilized solely to 

 test the various dyes selected for use. The dye 

 Rhodamine B was found to be the most satis- 

 factory and the use of a sporting bow with a glass 

 vial tipped arrow, figure IOC, proved to be a 

 successful means of dye application. 



49 



