Long-Term Measurement Records Related to Global Stratospheric Constituent Change IV
Presiding: R D McPeters, NASA Goddard Space Flight Center; R S Stolarski, NASA Goddard Space Flight Center
A54A-01 15:30h
Development of Long-term Datasets from Satellite BUV Instruments - The
The first BUV instrument was launched in April 1970 on NASA's Nimbus-4 satellite. More than a dozen instruments, broadly based on the same principle, but using very different technologies, have been launched in the last 35 years on NASA, NOAA, Japanese and European satellites. In this paper we describe the basic principles of the "soft" calibration approach that we have successfully applied to the data from many of these instruments to produce a consistent long-term record of total ozone, ozone profile and aerosols. This approach is based on using accurate radiative transfer models and assumed/known properties of the atmosphere in ultraviolet to derive calibration parameters. Although the accuracy of the results inevitably depends upon how well the assumed atmospheric properties are known, the technique has several built-in cross-checks that improve the robustness of the method. To develop further confidence in the data the soft calibration technique can be combined with data collected from few well-calibrated ground-based instruments. We will use examples from past and present BUV instruments to show how the method works.
A54A-02 15:45h
Solar Ultraviolet Spectral Irradiance Data for Atmospheric Studies
Spectral solar ultraviolet (UV) measurements began in late 1978 with Nimbus-7 SBUV, and have continued to the present using overlapping data sets from multiple instruments (SBUV/2 on NOAA satellites, UARS SUSIM and SOLSTICE). Solar irradiance in the middle and near ultraviolet wavelength region (200-400 nm) represents only 8% of the Sun's irradiance output, but has a profound effect on the Earth's stratosphere. Variations in mid-UV irradiance over a solar cycle constitute approximately 30% of the total observed solar energy variation. Solar mid-UV irradiance is deposited in the atmosphere at 30-50 km, so understanding the spectral and temporal dependence of these variations is critical to characterizing the long-term energy input to the stratosphere. The typical magnitude of irradiance variations over an 11-year solar cycle is 6-8% at 200 nm, 3-4% at 250 nm, and less than our current detection capabilities (1-2%) longward of 300 nm. Characterization of time-dependent solar UV variations for stratospheric data analysis or modeling has often been done using proxy indexes such as the 10.7 cm flux. While this index reproduces the general shape of solar variations on decadal timescales, it does not fully capture short-term variations that can be equal in magnitude to the solar cycle changes. The Mg II proxy index is more accurate for this purpose because it has a better physical connection to the mid-UV solar irradiance. We are developing a composite spectral irradiance data set that will provide a complete representation of solar UV forcing for analysis of long-term stratospheric changes during the period 1978-2004, and will continue into the future with measurements from the SORCE mission.
A54A-03 16:00h
Long-term Measurements of Solar Proton Fluxes (1963-Present) and the Subsequent Impact on Stratospheric Constituents
The fluxes of solar protons have been measured by satellites for over forty years (1963-present). Eight Interplanetary Monitoring Platform (IMP) satellites measured solar proton fluxes from 1963-1993 and five NOAA Geostationary Operational Environmental Satellites (GOES) were used for the period 1994-present. These high energy solar protons precipitate on the Earth's polar atmosphere sporadically, especially during solar proton events (SPEs), which typically last a few days. Solar protons with energies greater than 30 MeV are capable of reaching the stratosphere and causing increases in odd hydrogen (HOx) and odd nitrogen (NOy) constituents at polar latitudes (>60 degrees geomagnetic). The enhanced HOx leads to short-lived ozone depletion (~days) due to the short lifetime of HOx constituents. The enhanced NOy leads to long-lived ozone changes because of the long lifetime of the NOy family in the stratosphere. Several very large SPEs (August 1972, August and October 1989, July and November 2000, September and November 2001, and October 2003) over the 1963-2004 time period were simulated in the GSFC two-dimensional chemistry and transport model and were predicted to cause significant polar upper stratospheric ozone depletion >10%, which lasted for several weeks past the events. Several satellite instruments (BUV, SBUV, SBUV/2, SAGE II, HALOE, etc.) have shown constituent changes as a result of SPEs. Long-term (>40 years) model simulations of the influence of the solar protons and satellite measurements during and after some of the very large SPEs will be shown.
A54A-04 16:15h
The Solar Cycle Variation of Stratospheric Ozone: A Comparative Analysis of Version 8 SBUV(/2) and UARS HALOE Data
The observed solar cycle variation of ozone is a key constraint on climate models that include solar UV / ozone / dynamical coupling as a sun-climate forcing mechanism. Here, we report a comparative analysis of the solar cycle component of ozone interannual variability based on (1) the recently released Version 8 SBUV(/2) ozone profile data set extending from 1979 to 2003 (NASA Ozone Processing Team, http://code916.gsfc.nasa.gov/Data_services/); and (2) the UARS HALOE ozone profile data set extending from late 1991 to the present (NASA Langley Research Center, http://haloedata.larc.nasa.gov/). The two data sets are complementary. On the one hand, because HALOE is an occultation instrument, the vertical resolution of this data set is much higher than that of SBUV. On the other hand, the sampling frequency of the SBUV, which is a vertical sounder, is much greater than that of HALOE and the combined Version 8 data set covers a period of more than 25 years. The HALOE profile data (both sunset and sunrise) are first interpolated to pressure levels comparable to those for which Version 8 SBUV ozone data are available (1, 1.5, 2, 3, 5, 7, 10 hPa). Daily zonal averages are then calculated within 5-degree latitude zones if at least 10 profiles are available for a given latitude band and a given day. These daily zonal averages (typically several per month) are then averaged within 10 degree latitude zones and within 3-month intervals to construct seasonal zonal average time series. A similar procedure is applied to the Version 8 daily zonal mean SBUV data to calculate monthly and seasonal averages. Both data sets are then analyzed using a standard multiple regression statistical model including seasonal, QBO, solar cycle, and linear trend predictor terms. Results show that the solar cycle component is largest in the SBUV data over a broad range of latitudes near 1 hPa with an amplitude (solar max minus min) of 4 to 6 per cent while it is largest in the HALOE data near 2 hPa with an amplitude of about 4 per cent. A secondary maximum in the solar cycle component is also found in both data sets at middle latitudes near the 7 hPa level. In the lower stratosphere, a significant solar cycle variation is found in the HALOE data near the ozone concentration maximum. This lower stratospheric decadal variation appears to be mainly responsible for the solar cycle variation of total ozone that has been found in the merged TOMS / SBUV data set.
A54A-05 16:30h
The SSU Data Set and its Utilization with Other Long Term Data Sets to Reveal Climatic Trends over the past 25 Years
The Stratospheric Sounding Unit (SSU) has been operationally sounding the upper stratospheric temperatures for the past 25 years on various NOAA Polar Orbiting Environmental Satellites. The long term temperature data record is presented and examined. Challenges arising from changes of satellites and the precession of these satellites are examined. The extension of the SSU temperature data record utilizing the Advanced Microwave Sounding Unit-A (AMSU-A) will be presented. Trends of temperatures at various levels in the stratosphere will be examined in conjunction with that of the long term SBUV(/2) total ozone and profile ozone data sets.
http://www.cpc.ncep.noaa.gov/products/stratosphere/
A54A-06 16:45h
Interannual Variability of Stratospheric and Tropospheric Ozone Determined from Satellite Measurements
Long-term satellite records have been used in previous studies to examine both trends and interannual variability (IAV) of ozone in the stratosphere. In this study, we use satellite measurements to produce long-term records of both tropospheric and stratospheric ozone and we examine the IAV of these datasets. The long-term data record of tropospheric ozone residual (TOR) distributions [http://asd-www.larc.nasa.gov/TOR/data.html] has used concurrent measurements from the Total Ozone Mapping Spectrometer (TOMS) and Solar Backscattered Ultraviolet (SBUV) instruments to develop a quasi-global tropospheric ozone climatology. This climatology shows significant regional enhancements of ozone pollution resulting from the release of copious emissions from regionally industrialized areas in the Northern Hemisphere (east Asia, eastern U.S., northern India, western Africa) and widespread biomass burning in the Tropics. Because of the unique length and data density of this tropospheric trace gas data base, it is possible, for the first time, to examine the IAV of the TOR and to see if this IAV can be correlated with other well-known IAV parameters such as the quasi-biennial oscillation (QBO) and the El Niño/Southern Oscillation (ENSO). In addition, we can examine a complimentary integrated dataset that is also derived from the TOR methodology. The stratospheric column ozone (SCO) is the integrated amount of ozone above the tropopause and its climatological distribution is in excellent agreement with a comparable quantity derived from Stratospheric Aerosol and Gas Experiment (SAGE) profiles as well as with observations from ground-based and ozonesonde measurements. We can show that the IAV of SCO is consistent with earlier studies that have examined the relationship between TOMS total ozone and the QBO on relatively large spatial scales, which leads to an important confirmation of the use of TOR methodology to investigate IAV behavior. Whereas the QBO is observed on a large spatial scale in the stratosphere, we find that some of the regions where significant air pollution is found display IAV that is highly correlated with ENSO at certain times of the year.