摘要:

Shipboard (∼7 m) ozone measurements made in the equatorial Pacific Ocean between 20°N and 17°S and 140°–160°W confirm the existence of a distinct ozone minimum in the vicinity of the equator in the late spring, its decline in the summer, and its absence in autumn. This minimum could not be correlated with high biological activity in surface waters. Coincident aircraft measurements of ozone from near sea surface (50–100 m) to 2 km in altitude were made along 150°W at stations at 10°N, 0°, 5° and 12°S in May–June 1984. Aircraft data identified the existence of a distinct ozone maximum between the lifting condensation level (LCL) or cloud base (Zb) and the trade wind inversion, with ozone mixing ratios amounting to 2–2.5 times the ozone levels in the well‐mixed subcloud layer. A gradient of decreasing ozone with decreasing altitude extended from the LCL (orZb) to the near‐surface superadiabatic region

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13113

年代:1986

数据来源: WILEY

摘要:

A detailed statistical analysis of monthly averages of ozonesonde readings is performed to assess trends in ozone in the troposphere and the lower to mid‐stratosphere. Regression time series models, which include seasonal and trend factors, are estimated for 13 stations located mainly in the mid‐latitudes of the northern hemisphere. At each station, trend estimates are calculated for 14 “fractional” Umkehr layers covering the altitude range from 0 to 33 km. For the 1970–1982 period, our main findings indicate an overall negative trend in ozonesonde data in the lower stratosphere (15–21 km) of about −0.5% per year, and some evidence of a positive trend in the troposphere (0–5 km) of about 0.8% per year. An in‐depth sensitivity study of the trend estimates is performed with respect to various correction procedures used to normalize ozonesonde readings to Dobson total ozone measurements. The main results indicate that the negative trend findings in the 15 to 21‐km altitude region are robust to the normalization pr

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13121

年代:1986

数据来源: WILEY

摘要:

The purpose of the Balloon Ozone Intercomparison Campaign (BOIC) was to assess the accuracy and precision of various ozone measurement systems under development and those flown operationally. Ozone observations made by in situ UV absorption photometers from four groups, two solar UV absorption photometers, three varieties of electrochemical sondes, and a mass spectrometer were intercompared in three flight missions, each involving several balloon flights. Concurrent Umkehr and satellite observations were also intercompared. The National Bureau of Standards (NBS)provided a reference ozone source for intercomparing several of the in situ instruments at ground pressure. Harvard University and the University of Minnesota each developed a calibration facility after the BOIC flights which enabled a comparison of the flight in situ photometers under simulated stratospheric pressure and ozone concentrations. The following is a summary of results. The standard deviation of the sensitivities among 18 instruments tested about the NBS reference was 11%. These differences appear in flight at the lower altitudes, but they change at higher altitudes, indicating height dependent errors, particularly for the electrochemical sondes. Comparisons at the two laboratory facilities simulating stratospheric conditions indicated differences of about 2% at 3 mbar for two of the flight in situ photometers. Ozone values among four in situ UV photometers flown together had a standard deviation about the mean value of about ±3% from the tropopause to about 41 km. This is very close to the expected accuracy of these measurements and therefore is an excellent result. However, during float at 42 km the difference nearly doubled. Experiments performed during flight demonstrated that even near 40 km, wall losses in three UV photometers were less than 5%, which is consistent with the laboratory simulations. A comparison of a complement of electrochemical sondes yielded results that agreed with the mean of the in situ UV photometers to within 0–20%, depending on the sonde type and altitude. The electrochemical sondes gave systematically lower ozone values at pressures lower than 10 mbar (above 31 km). A comparison between an in situ UV and a solar absorption photometer indicated a 10% difference in the stratosphere, where the in situ measurement was lower. Comparisons of electrochemical sondes and Umkehr and Solar backscattered ultraviolet (SBUV) satellite observations showed agreement to within their error bars (stated to be about 5–10%). In two comparisons between in situ UV photometers and satellite measurements, a consistent difference occurred between 10 and 3 mbar (28–40 km), implying a possible bias between the measurement types. Intercomparisons among all the instruments in the troposphere showed 20–30% differences from the mean. A comparison of pressure measurements performed by several experimenters resulted in differences as high as ±15% from the average me

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13137

年代:1986

数据来源: WILEY

摘要:

An analysis procedure has been developed for derivation of information about the photochemical behavior of ozone near 1 mbar by explicitly accounting for the dynamical transport terms in the continuity equation for perturbations from the zonal mean. The procedure is shown to be valid using data from a numerical transport model and is then applied to LIMS ozone and temperature data, using geostrophic winds to estimate the transport terms. The data study is restricted to March at 2, 1 and 0.7 mbar. Because the temperature deviations are dynamically produced, large temperature deviations are associated with significant ozone transport terms. The anticorrelation between the deviations of ozone and temperature disappears when the transport terms are small. The derived photochemical information is compared to photochemical theory. Although there is overall agreement in the magnitude as well as the latitude, altitude, and time dependencies, discrepancies are suggested which may be related to the long‐standing failure of photochemical models to calculate ozone accurately near 1 mbar. The theory suggests that the addition of Clxto the stratosphere will affect the relationship of ozone and temperature at 2 and 1 mbar. Comparison of the photochemical information derived from future ozone and temperature measurements with the results of the present analysis should provide a critical test of the photochemical scheme thought to describe the behavior of odd chlorine in the stratospher

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13153

年代:1986

数据来源: WILEY

摘要:

In a simple three‐dimensional primitive equation model, a wave number 1 major stratospheric warming is simulated. With the aid of two idealized tracers it is shown that the transport during a major warming event is characterized by a small, well‐organized tongue of subtropical air flowing around the displaced winter vortex into the polar cap and by a wide area with strong quasi‐horizontal mixing (surf zone). The description of these dynamical processes requires a full three‐dimensional space res

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13167

年代:1986

数据来源: WILEY

摘要:

A method is presented for rapid and accurate calculations of photodissociation rates needed for photochemical modeling of the stratosphere, which include the effects of molecular scattering. Under the assumption of isotropic scattering and diffuse surface reflection, the linearity of the radiative transfer equation is used to decompose the total diffuse radiance field into two subfields that are referred to as the atmospheric and surface components. The atmospheric component accounts for the portion of the diffuse field that arises from scattering of the direct solar beam, while the surface component accounts for the portion of the diffuse field associated with radiation (direct plus diffuse) reflected by the surface that is subsequently scattered. Furthermore, the surface component has been normalized with respect to the total reflected radiation, so that it represents a relative field that is independent of solar angle and surface radiation properties that are contained in a surface scaling parameter. This independence can be effectively utilized when calculating photolysis rates for a series of sun angles, since the surface field need only be computed once. When the atmospheric and surface components are appropriately normalized, the wavelength variation of the resultant fields is sufficiently smooth that by using nine nodal points between 300 and 730 nm and cubic spline interpolation, accurate values of these fields at intermediate wavelengths are rapidly obtained. Further reductions in computational time are achieved by applying Sokolov's iterative procedure of averaging functional corrections to calculate approximate solutions for the atmospheric and surface fields at the nodal points. For wavelengths greater than 340 nm, a single iteration is sufficient to give results that agree with the exact values to better than 10% at altitudes above 15 km. Three iterations are used at shorter wavelengths due to increases in optical depth. The accuracy of the method for calculating photodissociation rates of 27 photolysis processes at 40 altitude levels between 0 and 53 km is typically better than 5% for altitudes above 10 km and all zenith angles.

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13187

年代:1986

数据来源: WILEY

摘要:

Well‐known theoretical predictions suggest that variances of large‐scale atmospheric fluctuations, for scales somewhat shorter than those of the forcing mechanisms, should obey a power law,k−b, wherekis the horizontal wave number. The invariance of the exponentbwith season, hemisphere, and latitude is tested using satellite‐measured brightness temperatures. Global grids of TIROS‐N Microwave Sounding Unit channel 4 measurements, which closely approximate the 30‐ to 150‐mbar layer mean temperature, are constructed for January, March, and August 1979. These grids are zonally Fourier‐transformed, and the resulting spectra are averaged over four 18°‐wide latitude bands. Fits of a power law to these spectra over wave numbers 10–36 and 10–26 give values ofbwhich are independent of season, hemisphere, and latitude band, to within statistical uncertainties. The observed values ofbare about 3.6, as compared to theore

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13195

年代:1986

数据来源: WILEY

摘要:

Variance power spectra of potential temperature, ozone, carbon monoxide, and water vapor at airliner cruise altitudes are presented. These results are based on data collected aboard commercial airlines at cruise altitudes during the Global Atmospheric Sampling Program (GASP). The horizontal scales (wavelengths) resolved by these data extend from 2.6–2400 km for temperature, 10–2400 km for ozone, 150–3000 km for water vapor, and 300–2500 km for carbon monoxide. The results divide into two distinct regimes in most cases, with the transition found at 500‐ to 800‐km wavelength. The long wavelength regime of temperature behaves as predicted by geostrophic turbulence theory, but only some of the chemical tracer results fit this model. At scales less than 500–800 km, spectral shapes of all tracers follow an approximately −5/3 power law dependence on wave number. At scales less than about 100 km, tropospheric ozone spectra follow a −1 power law. Spectral amplitudes of potential temperature and ozone are larger in the stratosphere than in the troposphere, while spectral amplitudes of carbon monoxide and water vapor are larger in the troposphere. The horizontal fluctuations giving rise to these spectra apparently result from that component of a spectrum of quasi‐horizontal displacements which acts orthogonal to the background gradient of each tracer. Numerical checks support this hypothesis for each of the chemical tracers, assuming the tracers are horizontally stratified. Finally, it is found that the frequency distribution of ozone spectral magnitude at a given wave number is appr

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13201

年代:1986

数据来源: WILEY

摘要:

This paper is concerned with the relationship between the spectrum of vertical displacements associated with the mesoscale spectrum of quasi‐horizontal motions in the atmosphere and the mesoscale spectra of scalar passive additives. This work is based on observations of mesoscale atmospheric wave number spectra of wind, temperature, and certain trace species sampled in the altitude range 9–14 km by commercial aircraft during the Global Atmospheric Sampling Program (GASP). The principal result is that the scalar spectra are reasonably consistent with a simple model in which scalar fluctuations are produced by quasi two‐dimensional motions acting in a plane inclined slightly to isentropic surfaces and to the isopleths of constant mixing ratio of trace sp

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13211

年代:1986

数据来源: WILEY

摘要:

We present the results of a series of research flights over the eastern equatorial Pacific that took place during various stages of the 1982–1983 El Niño/Southern Oscillation (ENSO) event. A continuous background was provided by satellite observations of significant convection (highly reflective cloud) and of atmospheric moisture and stability obtained from the TIROS Operational Vertical Sounder (TOVS). TOVS data showed a progressive moistening and destabilization of the lower troposphere in the eastern equatorial Pacific. Between April and July 1983, frequent periods of organized convective activity in this area were associated with incursions of surface westerly winds originating in the central and western Pacific. The flights across the equator in the eastern Pacific in early January 1983 recorded large positive sea surface temperature anomalies and corresponding strong moisture flux from the ocean to the lower troposphere, although there were no episodes of significant convection in the area until February 1983. A comparison with non‐ENSO conditions is provided by the data from a flight along a similar track in 1980. Flights in July and September 1983 took place after the reestablishment of trade winds in the area and show a gradual return toward normal conditions in the meteorological variables exam

ISSN:0148-0227    

DOI:10.1029/JD091iD12p13217

年代:1986

数据来源: WILEY