MONTHLY CHARTS OF MEM, MINIMUM, AND MAXIMUM 

 SEA SURFACE TEMPERATURE OF THE INDIAN OCEAN 



Introduction 



The Naval Oceanographic Office is currently engaged in producing a 

 series of atlases on the oceans of the world. In these atlases the 

 Physical Properties Section deals mainly with the distribution and 

 variation of three basic parameters: temperature, salinity, and density. 

 While analyses of these parameters are made as complete as present data 

 allow, undoubtedly some modifications will be necessary with the 

 collection of new data. 



The charts and graphs of sea surface temperature in the atlases as 

 well as in this publication, however, are based on ship injection data 

 so numerous in many regions that little future modification may be 

 necessary. Therefore, these charts are being published herein until a 

 more extensive analysis can be presented in Pub. No. 70k "Oceanographic 

 Atlas of the Indian Ocean Section II, Physical Properties." The current 

 need for sea surface temperature charts for use in analyzing the inter- 

 national Indian Ocean Expedition data has prompted an earlier release of 

 these charts. 



Description of the charts 



Sea surface temperatures are the most easily collected of oceano- 

 graphic measurements. In addition to oceanographic and naval vessels, 

 ships of opportunity furnish sea surface temperature data by their 

 reports of injection temperatures. 



Because injection temperatures are commonly taken below the surface 

 and may be influenced by heat from the ship's engines or boilers, they 

 are not individually considered as reliable as temperatures derived from 

 bucket thermometers or Nansen casts. However, if taken in sufficient 

 quantities by a number of ships over a prolonged period, the overall 

 reliability of injection temperature data improves considerably. 



When analyzing this type of data, the following criteria are used: 

 < 25 obs/l° square -- poor 

 25-99 obs/l° square — good 

 * 100 obs/l° square — excellent 



To show regions of reliability, those 1° squares containing 25 or 

 more observations are shaded on the presented charts. 



Mean, minimum, and maximum sea surface temperatures were analyzed 

 on monthly charts. These analyses were done on charts that had been 

 mechanically plotted by an X-Y plotter. The data on these charts con- 

 sisted of injection temperatures collected by various international 

 marine organizations and are retained in punch card form at the U. S. 

 National Weather Records Center, Asheville, North Carolina and at the 

 Naval Oceanographic Office. The data listed in the following table for 

 the marine decks cover the period from I85I+ until I96I. 



1 



