摘要:

Six water temperature anomalies were measured along two profiles each about 10 km in length at the TAG Hydrothermal Field on the east wall of the rift valley of the Mid‐Atlantic Ridge at latitude 26°N. The temperature anomalies were measured using a 3 m‐long vertical array of four thermistors towed within 20 m of the ocean bottom. The anomalies exhibit increases in potential temperature up to 0.127°C above ambient and inverse gradients warming downwards as great as 4.2 × 10−2°C m−1. The temperature anomalies are distributed as point sources in a linear pattern about 7 km in length along known fault zones in the east wall of the rift valley between depths of 2750 and 3200 m below sea level associated with hydrothermal mineral deposits. The characteristics of the temperature anomalies and their geologic setting indicate an origin by discharge of hydrothermal solutions through the faults in the rift valley wall. The magnitudes of the anomalies are consistent with values previously used to estimate a heat output of the order of several megawatts per kilometer of ridge at the TAG Hydroth

ISSN:0094-8276    

DOI:10.1029/GL005i012p00993

年代:1978

数据来源: WILEY

摘要:

The increase in atmospheric CO2of approximately 50 ppm from the mid‐nineteenth century to 1972 has led to a corresponding increase in the pCO2of sea water. The record of this increase is present in the oceanic water masses, though the signal is obscured. By observing the alkalinity and total CO2concentration within a water mass, and stripping off the perturbations of the CO2system due to respiration, carbonate dissolution and nitrate addition, the original atmospheric equilibration signal may be recovered. The application of these calculations to GEOSECS (1972) data from the core of the Antarctic Intermediate water reveals propagation of the atmospheric CO2signal northward

ISSN:0094-8276    

DOI:10.1029/GL005i012p00997

年代:1978

数据来源: WILEY

摘要:

Recently evidence has been accumulating pointing to the possibility of a sink for atmospheric trace gases in the desert areas of the world, specifically the Sahara. The proposed mechanism involves adsorption of molecules onto silicate surfaces, and photolysis of the adsorbed molecules by long‐wave solar radiation (λ>300 nm). To obtain data on this possible sink mechanism we took part in flights over East Africa, the Mediterranean Sea, and the Atlantic Ocean. We collected air samples in dust clouds over East Africa, and in non‐dusty air over Africa, the Mediterranean, and the Atlantic. The results of our measurements show that the samples of air collected in the dust clouds have significantly lower concentrations of N2O, CCl4, and CH3CCl3, whereas there is no significant difference between the dusty and non‐dusty air samples for CF2Cl2and CFCl3. This is in general agreement with the experimental results, which found that CCl4is photolyzed much more rapidly than CFCl3and CF2Cl2. However, the differences in N2O, CCl4, and CH3CCl3concentrations between dusty and non‐dusty air samples are relatively small, and the number of samples is insufficient to support any firm conclusions. The most that can be said is that the results of our measurements are consistent with the hypothesis that desert regions may be acting as sinks for a number of atmospheric trace gases, and that further research is clearly needed in t

ISSN:0094-8276    

DOI:10.1029/GL005i012p01001

年代:1978

数据来源: WILEY

摘要:

Reactions of ClOO with NO were studied by the photolysis of Cl2in the presence of NO and O2with or without added N2using steady state photolysis. ClOO is formed by the reversible reaction The results indicate that ClOO reacts with NO via two channels: The atmospherically important values k2aK1,−1= (1.5 ± 0.6) × 10−32cm6s−1and k2bK1,−1= (1.6 ± 1.0) × 10−31cm6s−1were evaluated at 298°K based on the value of (1.1 ± 0.3) × 10−31cm6s−1for the reaction The ratio k2b/k2awas found to be 11.0 ± 2.2. The values of k2aK1,−1and k2bK1,−1obtained in the present work when combined with a reasonable value of K1,−1at stratospheric temperatures indicates that reactions 2a and 2b are probably not

ISSN:0094-8276    

DOI:10.1029/GL005i012p01005

年代:1978

数据来源: WILEY

摘要:

Times of vein mineral deposition in the ocean crust have been determined both by Rb‐Sr isochron ages of vein smectites and by comparison of87Sr/86Sr ratios of vein calcites with the known variations of seawater87Sr/86Sr ratio with time. Results from drill sites 105, 332B and 418A, Atlantic Ocean, which have basement formation ages of 155 m.y., 3.5 m.y., and 110 m.y., respectively, show that vein deposition is essentially complete within 5‐10 m.y. after formation of the basaltic crust. This provides direct evidence that hydrothermal circulation of seawater through the oceanic crust is an important process for only 5‐10 m.y. after crust form

ISSN:0094-8276    

DOI:10.1029/GL005i012p01009

年代:1978

数据来源: WILEY

摘要:

The thermal excitation of diurnal and semidiurnal tidal modes due to insolation absorption by O3and H2O is investigated. Significant structural and seasonal differences from the heating profiles given byChapman and Lindzen(1970) are reported.

ISSN:0094-8276    

DOI:10.1029/GL005i012p01013

年代:1978

数据来源: WILEY

摘要:

The stratospheric H2O mixing ratio profile in the 10‐24 km altitude range is derived from in‐situ measurements, using a new technique: OH fluorescence produced when H2O molecules are photodissociated by a V.U.V. light source. The flight instrument and its calibration are described in some details. A decrease of the mixing ratio is observed below 24 km, down to 21 km. The stratospheres‐troposphere transition shows vertical stru

ISSN:0094-8276    

DOI:10.1029/GL005i012p01017

年代:1978

数据来源: WILEY

摘要:

Shipboard measurements of stratospheric NO2between 42° and 55° in the southern hemisphere during July 1978 show an abrupt change in the daytime abundance near 50°S similar to that seen in the northern winter hemisphere. The antarctic transition is the sharper, possibly as a result of higher stability in stratospheric zonal fl

ISSN:0094-8276    

DOI:10.1029/GL005i012p01021

年代:1978

数据来源: WILEY

摘要:

A direct measurement of the nitric oxide mixing ratio between 43 km and 61 km was made with a rocket‐borne chemiluminescent detector. This was the second flight in a series of two designed primarily to determine feasibility. The rocket was launched at Wallops, Island, Virginia on 19 March 1976 at 14:15 EST. The ozone‐generated background signal was monitored throughout the flight by periodically interrupting the atmospheric sample flow with a pure‐ N2bias‐supply gas. An extensive error analysis was performed to evaluate the uncertainty in our results. The discovery of computational and calibration‐gas concentration errors required us to reanalyze the results from the first flight of this detector in 1975; the corrected results are reported here. A comparison of the results from the two flight

ISSN:0094-8276    

DOI:10.1029/GL005i012p01023

年代:1978

数据来源: WILEY

摘要:

Samples of stratospheric air were obtained at altitudes up to about 35 km from balloon flights carried out at 4°S (Brazil), 78°S (Antarctica), and 41°N (two flights, Wyoming) in 1978. The samples obtained were analyzed for methane using a gas Chromatograph with flame ionization detection. The two Wyoming profiles and the Antarctica profile are similar. However, the Brazil profile, which is the first low‐latitude stratospheric‐methane profile reported, falls off much less rapidly with altitude, even when reduced to a common tropopause reference. The use of these methane profiles to deduce OH profiles is ex

ISSN:0094-8276    

DOI:10.1029/GL005i012p01027

年代:1978

数据来源: WILEY