968 MONTHLY WEATHER REVIEW APRIL,1931 BUCKET OBQERVATIONS OF SEA-SURFACE TEMPERA- TABLE1.-Lengths of 'iQuarter-mnths" ueed in computing mean TURES sea-surface temperatures By GILES SLOCIJM Days of month included in quarter STRAITS FLORIDA AND CARIBBEAN SEA OF Length of month The temperatures herein published are the means of I the average temperatures for the four quarters of the ~--- 25 davs...... 1-7 '114 ::!21 I:= month, except that, in the case of the 5' subdivisions of 29 days...... 1-7 I ai4 I I the Caribbean Sea, the figures shown are the simple means 30 days ______.______1-7 8-15 of the observed temperatures with the entire month 31 days ...... 1-7 8-15 taken 88 a unit. Table 1 shows the lengths of the quar- ters for each length of month. Table 2 shows the average temperature for the Carib- TABLE2.-Mean sea-surface temperatures in the Caribbean Sea and bean Sea and the Straits of Florida for April of each year the Straits of Florida for April (1919-1930) from 1919 to 1930, inclusive, and Table 3 summarizes the temperature for the month in the same areas, includ- 1 CaribbeanSea Stralts of Florida ing the departures of the April, 1930, means from the I Tear Number MW Number Mean 11-year means for April (1920-1930), and the changes of obser- temper- of obser- temper- from the temperatures for the preceding month of vations ature vations ature March, 1930. -- The chart shows the number of observations taken 1919 ...... 43 79. 1 14 7s. 9 1920.--...... 155 79.3 34 70.8 during the month of April, 1930, within each 1' square; 1921...... 179 78.4 443 70.9 1922...... 194 78.6 74 77.2 the mean temperature of the Straits of Florida, and of 19%...... 359 78.8 108 77.6 each subdivision of the Caribbean Sea; the 11-year 1924 ...... 342 79.6 108 70.4 5' 5' 1925 ...... 251 79.6 101 70.6 means (1920-1930) for these areas; and the local mean 1926...... 302 80.1 110 70.8 1927 ...... 313 80.0 iae 77.a time corresponding to Greenwich mean noon, at which 1929 ...... 435 79.6 16s 70.1 time the mariners are instructed to make the temper- 11128 ...... 49b 79.4 1% 78.0 ature readings. 1930- ...... 580 79.4 127 76.1 During April, temperatures in both the Straits of Mean (19zc-1930) ...... 1...... I 79.3 76.9 Florida and the Caribbean Sea continue to possess 1 Not used in computations because of insufficient data. distinctly cool-season values, the Bpril 11-year means for both areas being intermediate between those for Decem- ber and Jmuary. The trend is, however, distinctly TABLE3.-Alean sea-surface temperatures and number of obser- upward, and the last quarter of April is approiimately vations, April, 1930 Io warmer than the same quarter of March in the Carib- bean Sea. In the Straits of Florida the temperature I I Caribbean Sea 1 Straits of Florida difference is nearly 2'. I I- I I Depar- The surface water was slightly cooler than the 11-year ture Change Num- average during the first half of April, 1930 in the Straits Quarter Period Num- from from ber of Mean 11-pear preced- :tie;! of Florida. In the Caribbean Sea, the northwestern obsa- mean ing vatlonr (1920- month vation' portion was somewhat cooler than the average, while the 1930) temperature departures were positive over the remainder ' F. of the sea with the exception of the eastern extremity, -I---' F. ' F. where available data give evidence of cooler water than I...... Apr. 1 to 7. 125 79.3 ...... 33 I1 ...... Apr. 8 to 15. 146 70.1 ...... 36 in March. For the Caribbean as a whole, the departures 111 ...... Apr. 16 to 140 79.4 ...... 37 22. were small throughout the month. I\-.-. ____ Apr. 23 to 169 79.8 ...... 21 30. 1 In 8 CBBBS, 8s Indicated on the chart, the observations from small, little traveled, and unimportant mew at the outer limits of the Carlbbean'Sea have been treated BS parts Month ...I...... I MI0 79.4 +o. 1 +0.5 127 d wntiguous So subdivisions.

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