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Miller, Alvin J.

Publications and source records attributed to Miller, Alvin J..

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Upper-Stratospheric Ozone Trends 1979-1998

Extensive analyses of ozone observations between 1978 and 1998 measured by Dobson Umkehr, Stratospheric Aerosol and Gas Experiment (SAGE) I and II, and Solar Backscattered Ultraviolet (SBUV) and (SBUV)/2 indicate continued significant ozone decline throughout the extratropical upper stratosphere from 30-45 km altitude. The maximum annual linear decline of -0.8 +/- 0.2 %/yr(2sigma) occurs at 40 km and is well described in terms of a linear decline modulated by the 11-year solar variation. The minimum decline of -0.110.1% yr-1(2o) occurs at 25 km in midlatitudes, with remarkable symmetry between the Northern and Southern Hemispheres at 40 km altitude. Midlatitude upper-stratospheric zonal trends exhibit significant seasonal variation (+/- 30% in the Northern Hemisphere, +/- 40% in the Southern Hemisphere) with the most negative trends of -1.2%/yr occurring in the winter. Significant seasonal trends of -0.7 to -0.9%/yr occur at 40 km in the tropics between April and September. Subjecting the statistical models used to calculate the ozone trends to intercomparison tests on a variety of common data sets yields results that indicate the standard deviation between trends estimated by 10 different statistical models is less than 0.1%/yr in the annual-mean trend for SAGE data and less than 0.2%/yr in the most demanding conditions (seasons with irregular, sparse data) [World Meteorological Organization (WMO), 1998]. These consistent trend results between statistical models together with extensive consistency between the independent measurement-system trend observations by Dobson Umkehr, SAGE I and II, and SBUV and SBUV/2 provide a high degree of confidence in the accuracy of the declining ozone amounts reported here. Additional details of ozone trend results from 1978 to 1996 (2 years shorter than reported here) along with lower-stratospheric and tropospheric ozone trends, extensive intercomparisons to assess relative instrument drifts, and retrieval algorithm details are given by WMO [1998].

Newchurch, M. J.↗
NASA NTRS2001

Evidence for Large Decadal Variability in the Tropical Mean Radiative Energy Budget

It is widely assumed that variations in the radiative energy budget at large time and space scales are very small. We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought. We demonstrate that the radiation budget changes are caused by changes In tropical mean cloudiness. The results of several current climate model simulations fall to predict this large observed variation In tropical energy budget. The missing variability in the models highlights the critical need to Improve cloud modeling in the tropics to support Improved prediction of tropical climate on Inter-annual and decadal time scales. We believe that these data are the first rigorous demonstration of decadal time scale changes In the Earth's tropical cloudiness, and that they represent a new and necessary test of climate models.

Wielicki, Bruce A.↗
NASA NTRS1999

Constructing Synoptic Maps of Stratospheric Column Ozone from HALOE, SAGE and Balloonsonde Data Using Potential Vorticity Isentropic Coordinate Transformations

In this study we utilize potential vorticity - isentropic (PVI) coordinate transformations as a means of combining ozone data from different sources to construct daily, synthetic three-dimensional ozone fields. This methodology has been used successfully to reconstruct ozone maps in particular regions from aircraft data over the period of the aircraft campaign. We expand this method to create high-resolution daily global maps of profile ozone data, particularly in the lower stratosphere, where high-resolution ozone data are sparse. Ozone climatologies in PVI-space are constructed from satellite-based SAGE II and UARS/HALOE data, both of which-use solar occultation techniques to make high vertical resolution ozone profile measurements, but with low spatial resolution. A climatology from ground-based balloonsonde data is also created. The climatologies are used to establish the relationship between ozone and dynamical variability, which is defined by the potential vorticity (in the form of equivalent latitude) and potential temperature fields. Once a PVI climatology has been created from data taken by one or more instruments, high-resolution daily profile ozone field estimates are constructed based solely on the PVI fields, which are available on a daily basis from NCEP analysis. These profile ozone maps could be used for a variety of applications, including use in conjunction with total ozone maps to create a daily tropospheric ozone product, as input to forecast models, or as a tool for validating independent ozone measurements when correlative data are not available. This technique is limited to regions where the ozone is a long-term tracer and the flow is adiabatic. We evaluate the internal consistency of the technique by transforming the ozone back to physical space and comparing to the original profiles. Biases in the long-term average of the differences are used to identify regions where the technique is consistently introducing errors. Initial results show the technique is useful in the lower stratosphere at most latitudes throughout the year,and in the winter hemisphere in the middle stratosphere. The results are problematic in the summer hemisphere middle stratosphere due to increased ozone photochemistry and weak PV gradients. Alternate techniques in these regions will be discussed. An additional limitation is the quality and resolution of the meteorological data.

Hollandsworth, Stacey M.↗
NASA NTRS1994

Ozone determinations with the NOAA SBUV/2 system

The NOAA satellite ozone monitoring program was initiated by the National Environmental Satellite Data and Information Service (NESDIS) in December 1984, with the launch of the NOAA-9 spacecraft carrying the first operational Solar Backscatter Ultraviolet Spectrometer (SBUV/2). This instrument and its successor on NOAA-11, launched in 1988, are similar to the SBUV instrument launched by the NASA in 1978 on the Nimbus-7 research spacecraft. Measurements by the SBUV and SBUV/2 instruments overlap beginning in 1985. These instruments use measurements of the reflected ultraviolet solar radiation from the atmosphere to derive total ozone amounts and ozone vertical profiles. Since launch, the NOAA instruments and the derived products have been undergoing extensive evaluation by scientists of NOAA and NASA. Measurements obtained with these instruments are processed in real time by the NESDIS. These are reprocessed as the SBUV/2 instrument characterization is refined and as the retrieval algorithm for processing the data is improved. The NOAA-9 ozone data archive begins in March 1985 and continues through October 1990. The archive of NOAA-11 data begins in January 1989 and the data continues to be acquired in 1992.

Planet, Walter G.↗
NASA NTRS1994

Seasonal trend analysis of published ground-based and TOMS total ozone data through 1991

A seasonal trend analysis of published Dobson (including stations' newly revised and Brewer-simulated Dobson) total ozone data through 1991 from a network of 56 stations has been performed, using three different data periods. The trend results for the longest data period 1964 - 1991 indicate substantial negative trends in ozone in the higher northern latitudes during the winter and spring seasons, some evidence of negative trend in the higher southern latitudes (30 deg S - 55 deg S) during all seasons, and trends close to zero for all seasons over the 30 deg S - 30 deg N latitude range. For the shortest data period, November 1978 through 1991, there is a clear indication that trends have become more negative in the higher northern latitudes, especially during the winter and spring seasons, and also in the higher southern latitudes in all seasons. A seasonal trend analysis of zonal averages of total ozone mapping spectrometer (TOMS) satellite total ozone data for the comparable period November 1978 through 1991 has also been performed, and moderately good agreement is found between trends in Dobson and TOMS data over this period.

Reinsel, Gregory C.↗
NASA NTRS1993

The Sub-bureau for Atmospheric Angular Momentum of the International Earth Rotation Service - A meteorological data center with geodetic applications

By exchanging angular momentum with the solid portion of the earth, the atmosphere plays a vital role in exciting small but measurable changes in the rotation of our planet. Recognizing this relationship, the International Earth Rotation Service invited the U.S. National Meteorological Center to organize a Sub-bureau for Atmospheric Angular Momentum (SBAAM) for the purpose of collecting, distributing, archiving, and analyzing atmospheric parameters relevant to earth rotation/polar motion. These functions of wind and surface pressure are being computed with data from several of the world's weather services, and they are being widely applied to the research and operations of the geodetic community. The SBAAM began operating formally in October 1989, and this article highlights its development, operations, and significance.

Salstein, David A.↗
NASA NTRS1990

A comparison of Arctic lower stratospheric winter temperatures for 1988-89 with temperatures since 1964

Lower stratospheric temperatures during the Airborne Arctic Stratospheric Expedition are compared with temperatures available since January, 1964. January, 1989, was the coldest averaged January in the last 26 years at high latitude, lower stratospheric levels. There have been other months with temperatures almost as low as the level of January, 1989, and localized temperatures (e.g., minimum polar vortex temperatures) have been lower than that encountered in January 1989. February, 1989, was warmer than average and March, 1989, had some of the highest polar vortex temperatures in the last 26 years. Conditions were therefore not very favorable for Polar Stratospheric Cloud (PSC) formation into early spring.

Nagatani, Ronald M.↗
NASA NTRS1990

Atmospheric energetics and earth radiation budget

Processed ERBE data are used in several studies in which NMC global analyses and forecasts are examined and evaluated. In the first study, ERBE net radiation values for four months are averaged and integrated to provide global net energy transport. Energy transport by atmospheric circulations is obtained using NMC analyses and results provide a measure of reasonableness of the analyses. In the second and third experiments, ERBE values of outgoing longwave radiation are used as 'top-side truth' to examine both the spin-up problem and the radiation algorithms of the global forecasts.

Kann, Deirdre M.↗
NASA NTRS1988

Use of operational analyses to study the dynamics of troposphere-stratosphere interactions in polar regions

Operational analyses produced by large weather centers have been used in the past to monitor various aspects of the general circulation as well as address dynamical questions. For a number years researchers have been monitoring National Meteorological Center (NMC) analyses at 100 millibars because it is the level from which stratospheric analyses are built. In particular, they closely examined the pressure-work term at that level which is an important parameter related to the forcing of the stratosphere by the troposphere. Rapid fluctuations typically seen in this quanity during the months of July-November, and similarly noted by Randel et al., (1987) may raise some concern about the quality of the analyses. Researchers investigated the behavior of the term mainly responsible for these variations, namely the eddy flux of heat, and furthermore have corroborated the presence of these variations in contemporaneous analyses produced by the European Centre for Medium Range Forecasts (ECMWF). Researchers demonstrated that fluctuations in standing eddy heat fluxes, related to the forcing of the stratosphere by the troposphere, agree in two largely independent meteorological analyses. Researchers believe, that these fluctuations are mostly real.

Salstein, David A.↗
NASA NTRS1988

Comparison of total ozone amounts derived from satellite and ground-based measurements

Total ozone amounts derived from the NOAA operational sounder (TOVS) are compared to measurements from Nimbus-7 SBUV and ground-based Dobson spectrophotometer observations over a seven-year period. The global trends of the data, in terms of deviations from long-term averages, derived from measurements by each satellite instrument show qualitative agreement until mid-1984 when the data diverge with the TOVS-derived data showing higher values. Additionally, more significant differences appear in both the north and south temperate zones' records. The trends derived from the satellite systems' measurements also show differences from that of the Dobson instrument measurements with the trend of the TOVS measurements showing generally better overall agreement with the Dobson data record.

Planet, Walter G.↗
NASA NTRS1987

Medium-range numerical forecasts of atmospheric angular momentum

Forecasts of zonal wind fields produced by the medium-range forecast (MRF) model of the National Meteorological Center are used to create predictions of the atmosphere's angular momentum at lead times of 1-10 days. Based on momentum forecasts archived for the period December 1985-November 1986, it is found that, on average, the MRF exhibits positive skill relative to persistence-based forecasts at all lead times. Over the entire one-year study period, the improvement over persistence exceeds 20 percent for 2-6 day forecasts and remains as large as 10 percent even for 10-day forecasts. On the other hand, skill scores for the MRF momentum predictions vary considerably from month to month, and for a sizable fraction of the study period, the MRF is less skillful than persistence.

Rosen, Richard D.↗
NASA NTRS1987

Accuracy of atmospheric angular momentum estimates from operational analyses

An attempt is made to assess the accuracy of global atmospheric angular momentum determinations by comparing time series of this quantity derived from both the NMC and ECMWF zonal wind analyses for 1981-85. Over this period, the rms difference betwen the two atmospheric series is comparable to the difference between an atmospheric momentum series and the series that is consistent with observed (nontidal) changes in earth rotation. Most of the difference between the NMC and ECMWF global momentum values comes from the region between 33 deg S and 16 deg N. Differences between NMC and ECMWF regional momentum values become vanishingly small in the high latitudes of the Northern Hemisphere, but they remain large throughout the entire Southern Hemisphere. An annual signal of up to 0.5 m/s exists in the difference between the NMC and ECMWF tropospheric zonal wind fields. Although seemingly small, this signal is vertically coherent and leads to a marked annual component in the NMC-ECMWF difference momentum values in the tropics and also for the Northern Hemisphere as a whole.

Rosen, Richard D.↗
NASA NTRS1987

The influence of lower stratospheric forcing on the October Antarctic ozone decrease

A pattern correlation is found between the 30-mb zonal average ozone and temperature at 70 deg S during the October months and the 100-mb Eliassen-Palm (E-P) fluxes for the seven Septembers of 1979 to 1985, suggesting a dynamical influence on the long term trend of ozone and temperature values in the Southern Hemisphere for this period. For the August E-P fluxes and September values, this relationship is found to hold for temperature while not being strong for ozone. No explanation is found for the anomalously warm temperature values noted for both September and October 1982.

Nagatani, Ronald M.↗
NASA NTRS1987

Statistical analysis of total ozone and stratospheric Umkehr data for trends and solar cycle relationship

Dobson total ozone data from 1970-1984 and stratospheric Umkehr profile ozone data from 1970-1981 are analyzed. The relationship between ozone and long-term solar cycle activity is examined using 10.7 cm solar flux data. From the Dobson data it is estimated that the overall global trend in total ozone is -0.26 + or -0.92 percent per decade, which indicates no significant overall trend; and for the total ozone-solar flux relationship there is a 1.18 + or - 0.66 percent change in total ozone from solar cycle minimum to maximum that reveals a positive relationship. Analysis of the Umkehr data reveals a negative trend of -0.30 + or - 0.17 percent per year in the layers 7 snd 8. The relationship between Umkehr data and solar flux in layers 6 and 7 is 2.57 + or - 1.25 percent and 3.40 + or - 2.16 percent change from solar cycle minimum to maximum; however, no significant relationship is detected in the higher layers 8 and 9. These estimates are compared with theoretical model calculations. It is noted that the estimated effects of solar cycle activity on total ozone and stratospheric ozone agree with calculations of photochemical models.

Reinsel, Gregory C.↗