1969 NOTES AND CORRESPONDENCE785in the vertical is undoubtedly of great importance inthe processes studied by Gathman and Trent. Althoughthey mention some effort was made to correlate an airsea temperature difference with their space charge measurements, no further mention of this test was noted inthe text. It seems likdy that the inclusion of some air-seatemperature differential categories would have explained much of the scatter from their wind vs spacecharge correlations. The U.S.N.S. Eltanin cruise was primarily throughthe tropical equatorial region of the mid-Pacific wherean inversion predominates and considerable variationmay be expected in low-levd wind vdocity. Gathmanand Trent note a similar difficulty that was encounteredby Monahan (1968) when wind speeds ranged between6 and 20 kt. It is similarly unfortunate that Monahanhas neglected to consider the consequences of atmospheric stability in his treatment of "sea spray as a function of low devation wind speed." Past studies on the Great Lakes have shown the wide spectrum of air-water temperature differences that occur within a year (Strong, 1968a; Bellaire, 1965). An altered lapse rate from superadiabatic to inversion (Tai,>>T,~) conditions can be responsible for reducing a 1 m white capped sea to a completely smooth surface. During stable spring periods when warm air is advected lakeward, cold waters have been ob served to reduce the wind profile as a function of the inversion stratification. As a consequence, wave generation forces may be completely dissipated. These studiesemphasize the need for inclusion of some measure ofstratification just above the air-sea interface when aninvestigation of the environment on either side of thisinterface is made. REFERENCESBellaire, F. R., 1965: The modification of warm air moving over cold water. Pro*. 8th Conf. Great Lakes Re*., Univ. of Michigan, Great Lakes Res. Div., Publ. No. 13, 249-256.Brown, P. R., 1953: Wave data for Eastern North Atlantic. Marine Observers, 23, No. 160, 94-98.Gathman, S., and Eva Mac Trent, 5968: Space charge over the open ocean. Y. Atmos. Sd., 25, 1075-1079.Jacobs, S. J., 1965: Wave hindcasts vs recorded waves. Final Rept.. No. 06768~1-f, Office of Res. Admin., Univ. of Michigan, 35 pp.Monatan, Edward C., 1968: Sea spray as a function of low elevation wind speed. J. Geophys. Res., 73, 1127-1137.Ragotzkie, Robert A., 1962: Effect of air stability on the develop ment of wind waves on lakes. Limnol. Oceanog., 7, 248-251.Richards, T. L., H. Dragert and D. R. Mclntyre, 1966: Influence of atmospheric stability and over-water fetch on winds over the lower Great Lakes. Mon. tVea. R~v., 94, 448-453.Strong, Alan E., 1968a: Weather and Waves. Limnos, 1, 22-28.- ,1968b: The spring lake anticyclone: Its inducement on theatmospheric and water circulations. Ph.D. thesis, Dept. ofMeteorology and Oceanography, University of Michigan,146 pp.- ., and F. R. Bellalre, 1965: The effects of air stability on wind and waves. ~Vroc. 8th Conf. Great Lakes Res., Univ. of Michigan, Great Lakes Res. Div., Publ. No. 13, 283-289. Reply S. Gn~m~ ~) Evn M~ T~U. $. Naval Research Laboratory, Wa, hington, D. C.24 March 1969 As stated in the paper (Gathman and Trent, 1968)the temperature and wind monitoring equipment usedon board the USNS Eltanian was mounted at mastheight. To be more specific, it was located ~-1 m abovethe ice pilot h(ouse at approximately 18 m above thewater. The equipment was designed, installed andoperated by ESSA representatives on board ship. Acontinuous measurement of water temperature wasmade by means of a tethered "fish" which was kept ata relatively constant depth of <4 m below the surfaceo~ the water. The temperature gradient (T~--T,~) during theperiod of time that the atmospheric space charge wasmonitored remained within the range of +1.5C and--$.5C with a mean of approximately --0.5C. Thus, allthese data fall within the classification of neutralaccording to the definitions of stability given byRichards et aL (1966). Recent atmospheric electrical measurements made byGathman and Hoppel on the shores of Lake Superiorshow a marked effect by low level atmospheric stability. However, the difficulty in obtaining accuratestability measurements from a ship at sea for the smallrange of near zero temperature gradients encounteredon the Eltanin cruise precludes the use of this parameterin any predictive statement concerning the existence ofspace charge transfer.REFERENCESGathman, S., and Eva Mae Trent, 1968: Space charge over the open ocean. J. Atmos. $-i., 25, 1075-1079.Richards, T. L., H. Dragext and D. R. Mclntyre, 1966: Influence of atmospheric stability and over-water fetch on winds over the lower Great Lakes. Mon. Wea. Roy., 94, 448-453.