摘要:

Electric field measurements have been acquired inside an electrically active cell of a multicelled severe storm in Oklahoma with a free balloon‐borne instrument. The electrical measurements are analyzed in conjunction with standard weather radar and Doppler radar observations and standard meteorological measurements of the radiosonde in order to relate the inferred electrical structure with the precipitation and kinematic features of the cell. The precipitation and kinematic characteristics of the storm are consistent with those of the general model for a “typical” multicelled severe storm in a mature stage. The cell exhibited a bipolar charge structure with negative charge below positive charge, which was distributed throughout the upper portion of the cloud. The average charge concentrations of the two regions were estimated to be −1.2 and 0.15 nC m−3respectively. The upper positive charge was approximately 6 km in vertical extent, nonuniformly distributed, and was coincident with generally upward moving air. The lower negative charge was less than 1 km in vertical extent, centered near the −9°C atmospheric temperature level, and coincident with downdraft air in moderate precipitation. Near the top of the negative region, concentrated charge of approximately 17 nC m−3was measured with a vertical extent of at least 40 m. A screening layer of negative charge was detected at the upper boundary of the cloud. The layer was 200–250 m thick with an average charge concentratio

ISSN:0148-0227    

DOI:10.1029/JD092iD01p01017

年代:1987

数据来源: WILEY

摘要:

The deuterium/hydrogen ratios, expressed in terms of δD, of precipitation at Mohonk Lake, New York, from 118 individual storms during the six summers 1977–1982 have been measured and considered in light of the concurrent meteorological conditions. The so‐called amount effect of Dansgaard—summers with above average precipitation totals tend to have below average δD values is observed at Mohonk Lake and is also registered in the tree ring cellulose of water‐stressed Eastern White Pine. A similar amount effect is also observed for individual events and can be explained in terms of differences between convective and cyclonic precipitation. Stable cyclonic precipitation has much lower δD values (−64.8) but much greater amounts (3.77 cm) on average than purely convective storms (δD = −27.2, 1.30 cm). The seasonal amount effect is related to the fact that during the 6‐year observational period, wetter than normal summers at Mohonk Lake also had a higher than normal percentage of stable cyclonic precipitation and a lower than normal percentage of purely convect

ISSN:0148-0227    

DOI:10.1029/JD092iD01p01033

年代:1987

数据来源: WILEY

摘要:

Simultaneous measurements of short‐lived radon daughter concentrations and atmospheric stability in surface air have been continuously made at a site near the Japan Sea coast for a period of about 1 year. The atmospheric stability is related more closely to the concentration difference with respect to time than to the concentration level at that tim

ISSN:0148-0227    

DOI:10.1029/JD092iD01p01041

年代:1987

数据来源: WILEY

摘要:

Analyses for C1‐C4hydrocarbon concentrations and the13C/12C ratio in CH4were performed on two air samples collected in the Amazon jungle (3.5°S, 59°W) after the nearby release of biogenic gas bubbles. The CH4concentrations of each sample were greatly enhanced (4100 and 310 ppmv) over the background concentration (1.6 ppmv) for remote locations at that latitude and time. The13/12C ratio in this biogenic methane is depleted in13C (−64‰) relative to atmospheric CH4(−47‰), as is CH4from almost all other biogenic sources. Because laboratory measurements to date indicate only a very small13C/12C isotope effect in the reaction of CH4with HO, an apparent discrepancy remains between the13C/12C ratios of the known CH4sources and that of atmospheric CH4. Five other hydrocarbons (C2H6, C2H4, C3H8,i‐C4H10,n‐C4H10) were also found at the 1 to 35 ppbv level in the air sample with 4100 ppmv CH4. These concentrations are not large enough to indicate any major importance for this source in C2‐C4hydrocarbon budgets on either a global

ISSN:0148-0227    

DOI:10.1029/JD092iD01p01044

年代:1987

数据来源: WILEY