oLR (1990)37 (12) B. Marine Meteorology 1095

high winds is associated with the surface tearing. Coll. of Mar. Studies, Univ. of Delaware, 700 Pilottown Rd., Lewes, DE 19958, USA.

B250. Clouds 90:6973

Detwiler, Andrew, 1990. Analysis of cloud Imagery using box counting. Int. J. Remote Sens, 11(5): 887-898.

Photographic images of portions of an altocumulus cloud field were obtained from a rising balloon. They spanned a range of resolutions as the balloon rose. The fractal dimension of this field is estimated using a box-counting procedure. It is shown that the field is characterized by multiple fractal dimensions that vary with both intensity and scale. Inst. of Atmos. Sci., South Dakota School of Mines and Tech., 501 E. St. Jospeph St., Rapid City, South Dakota 57701, USA.

B270. Precipitation

90:6974 Andersson, TaRe and Stefan Nilsson, 1990. Topo-

graphically induced convective snowbands over the Baltic Sea and their precipitation distribution. Weather Forecasting, 5(2):299-312. Swedish Meteorol. and Hydrol. Inst., S-60176 Norr- koping, Sweden.

90:6975 Moiler, Dctlev, 1990. The Na/CI ratio in rainwater

and the seasalt chloride cycle. Tellus, (B)42(3): 254-262. Heinrich Hertz Inst. of Atmos. Res. and Geomagnetism, Acad. of Sci. of the GDR, Rudower Chaussee 5, DDR-1199 Berlin, DRG.

B310. Chemistry

90:6976 Khalil, M.A.K. and R.A. Rasmussen, 1990. Con-

straints on the global sources of methane and an analysis of recent budgets. Tellus, (B)42(3):229- 236.

Recent observations show that methane concentra- tions have increased at an average rate of 16.5 ppbv/yr over the last decade. The present lifetime of methane is 8-12 years. Taking into account the

�9 possibilities that the lifetime of methane has gotten longer over the last century because of a possible

decline in the natural sinks and that emissions from natural sources have also changed, we show that the anthropogenic fraction should be 40%-70%, and the total present emissions should be 420-620 Tg/y. Of 11 methane budgets analyzed over the last decade, only 2 meet these conditions. Inst. of Atmos. Sci., Oregon Grad. Ctr., 19600 N.W. Von Neumann Dr., Beaverton, OR 97006, USA.

90:6977 Rodhe, IIenning, 1990. A comparison of the contri-

bution of various gases to the greenhouse effect. Science, 248(4960): 1217-1219.

The current concern about an anthropogenic impact on global climate has made it of interest to compare the potential effect of various human activities. A case in point is the comparison between the emission of greenhouse gases from the use of natural gas and that from other fossil fuels. This comparison requires an evaluation of the effect of methane emissions relative to that of carbon dioxide emissions. A rough analysis based on the use of currently accepted values shows that natural gas is preferable to other fossil fuels in consideration of the greenhouse effect as long as its leakage can be limited to 3-6%. �9 by AAAS. Dept. o f Meteorol., Stockholm Univ., S-106 91 Stockholm, Sweden.

90:6978 Yurganov, L.N., 1990. Surface layer ozone above the

Weddell Sea during the Antarctic spring. Antarct. Sci, 2(2):169-174.

Ozone concentrations in the atmospheric surface layer above the Weddell Sea during the Antarctic spring, 1989, varied significantly. Lower levels of ozone were associated with colder Antarctic air masses and higher values with warmer mid-latitude air. The lowest ozone concentration was measured in the centre of a low pressure system. A definite diurnal variation of tropospheric ozone observed during clear days with low total ozone amount may be interpreted as a consequence of the occurrence of photochemical reactions under conditions of in- creased ultraviolet solar radiation. Arctic and Ant- arctic Res. Inst., 199226 Leningrad, USSR.

B320. Particulates (dust, aerosols, etc.)

90:6979 ttandler, Paul and Karen Andsager, 1990. Volcanic

aerosols, El Nifio and the Southern Oscillation. [Comments on Nicholls, 1988.] Int. J. Climatol, 10(4):413-424. Dept. of Phys., Univ. of Illinois, 110 W. Green St., Urbana, IL 61801, USA.