Roy Spencer - Academia.edu (original) (raw)

Papers by Roy Spencer

Energy Law Journal, Jul 1, 2011

Litigation regarding "climate change" allegedly caused by emissions of "greenhouse gases"-primari... more Litigation regarding "climate change" allegedly caused by emissions of "greenhouse gases"-primarily CO 2-has been winding its way through the federal court system for more than half a decade. The Supreme Court has now issued two opinions in climate change cases. The first opinion, in Massachusetts v. EPA, upheld a challenge to EPA's decision not to regulate CO 2 emissions and has led the EPA to begin rulemaking on greenhouse gases. The second, Connecticut v. AEP, shut the courthouse doors on cases seeking to enjoin CO 2 emissions under federal common law nuisance claims but left the door open to state law claims and possibly damages claims. With the doors to the federal courthouses still open at least a crack, and a spate of recent state complaints, climate litigation seems to be a new fact of life. As the initial challenges to justiciability are overcome, the next line in the sand may be challenges to the admissibility of plaintiff's scientific evidence. This article focuses on the admissibility of scientific testimony on causation in common law nuisance damages cases under the Daubert standard, which is followed in all federal courts and about half of the states' courts. The authors have collaborated to blend an analysis of scientific theories and legal principals. They conclude that based on the current state of climate science and the principles of Daubert, climate change theories are not yet well enough established to hold CO 2 emitters liable for damages in a court of law. * Mr. Harlow practices utility law and litigation with the Washington, D.C.-based firm Lukas, Nace, Gutierrez & Sachs, LLP. Although his focus is primarily energy and telecommunications, he has litigated cases before courts and agencies involving nearly all types of utilities. He has been an avid lay student of climate change for years. He wishes to acknowledge the assistance of Seattle attorney, Adam Jussel. * Dr. Spencer is a Principal Research Scientist at the University of Alabama in Huntsville. He earned a Ph.D. in meteorology from the University of Wisconsin in 1981. While at NASA, as a Senior Scientist for Climate Studies, he jointly received NASA's Exceptional Scientific Achievement Medal for his global temperature monitoring work with satellites. Dr. Spencer is the U.S. Science Team leader for the Advanced Microwave Scanning Radiometer on NASA's Aqua satellite. He has provided congressional testimony several times on the subject of global warming.

A technique for estimating the effect of scattering on the average brightness temperature, T(B), ... more A technique for estimating the effect of scattering on the average brightness temperature, T(B), is examined. This scattering method is based on the relation observed over land between the SMMR T(B) and radar-derived rain rate. The scattering algorithm was evaluated and a comparison of radar and SMMR images reveals a correlation between radar-reflectivity-derived rates and the SMMR rain rates. The limitations of the scattering technique are discussed. Graphs and images displaying the application of the scattering algorithm are presented.

The rain and ice signatures of tropical oceanic precipitation systems obtained with the Special S... more The rain and ice signatures of tropical oceanic precipitation systems obtained with the Special Sensor Microwave Imager (SSM/I) are examined. A method for polarization correction without the F8 SSM/I V85.5 channel is presented. As an example of the methodology, SSM/I imagery is used to study the ice and liquid features of Hurricane Gilbert.

Results are presented of an intercomparison between MSU channel 2 Tb and radiosonde data taking b... more Results are presented of an intercomparison between MSU channel 2 Tb and radiosonde data taking both oxygen and water vapor absorption into account. A total of 45 stations covering most of the central and eastern U.S. were included. Precise comparisons (to 0.1 C or better) between MSU Tb and radiosonde-calculated Tb were found to be possible with large numbers of stations and long averaging periods (many months), although they are not sufficient in number to address the previously documented monthly precision of 0.01 C from satellite-satellite intercomparisons. The MSU channel 2 does not have a 1:1 response to atmospheric temperature variations; the response averages about 92 percent. No evidence was found to suggest that procedural or hardware changes in the U.S. radiosonde system have caused any widespread biases between 1980 and 1986.

Microwave Remote Sensing of the Atmosphere and Environment III, 2003

The Advanced Microwave Scanning Radiometers (AMSR) are dual-polarized microwave radiometers havin... more The Advanced Microwave Scanning Radiometers (AMSR) are dual-polarized microwave radiometers having channel frequencies ranging from 6.9 GHz to 89 GHz, and were designed to retrieve global information on precipitation, sea surface temperature, oceanic surface winds and integrated cloud water and water vapor, vegetation, sea ice, and snow cover. Two AMSR&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s have been built by Mitsubishi Electric Corporation for the National

Journal of Climate and Applied Meteorology, 1983

The scattering algorithms of Spencer (1983, 1986) are applied to the December-May period from 198... more The scattering algorithms of Spencer (1983, 1986) are applied to the December-May period from 1981-1984, to obtain the 1982-1983 December-May convective precipitation anomaly patterns associated with the El Nino/Southern Oscillation. It is shown that semiannual convective precipitation patterns over global land and ocean regions can be mapped using the volume scattering effect of precipitation-size ice on Nimbus-7 SMMR 37 GHz brightness temperature. It is suggested that the Defense Meteorological Satellite Program Special Sensor Microwave/Imager 85 GHz data (in combination with 37 and 19 GHz data) can be valuable in global surveys of precipitation patterns.

Monthly Weather Review, 1995

Spatial fields of satellite-measured deep-layer temperatures are examined in the context of quasi... more Spatial fields of satellite-measured deep-layer temperatures are examined in the context of quasigeostrophic (level of insignificant dynamics) assumption of Hirshberg and Fritsch_

Monthly Weather Review, 2001

The first Advanced Microwave Sounding Unit temperature sounder (AMSU-A) was launched on the NOAA-... more The first Advanced Microwave Sounding Unit temperature sounder (AMSU-A) was launched on the NOAA-15 satellite on 13 May 1998. The AMSU-A's higher spatial and radiometric resolutions provide more useful information on the strength of the middle-and upper-tropospheric warm cores associated with tropical cyclones than have previous microwave temperature sounders. The gradient wind relationship suggests that the temperature gradient near the core of tropical cyclones increases nonlinearly with wind speed. The gradient wind equation is recast to include AMSU-A-derived variables. Stepwise regression is used to determine which of these variables is most closely related to maximum sustained winds (V max). The satellite variables investigated include the radially averaged gradients at two spatial resolutions of AMSU-A channels 1-10 T b data (␦ r T b), the squares of these gradients, a channel-15-based scattering index (SI 89), and area-averaged T b. Calculations of T b and ␦ r T b from mesoscale model simulations of Andrew (1992) reveal the effects of the AMSU spatial sampling on the cyclone warm core presentation. Stepwise regression of 66 AMSU-A terms against National Hurricane Center V max estimates from the 1998 and 1999 Atlantic hurricane season confirms the existence of a nonlinear relationship between wind speed and radially averaged temperature gradients near the cyclone warm core. Of six regression terms, four are dominated by temperature information, and two are interpreted as correcting for hydrometeor contamination. Jackknifed regressions were performed to estimate the algorithm performance on independent data. For the 82 cases that had in situ measurements of V max , the average error standard deviation was 4.7 m s Ϫ1. For 108 cases without in situ wind data, the average error standard deviation was 7.5 m s Ϫ1. Operational considerations, including the detection of weak cyclones and false alarm reduction, are also discussed.

Journal of the Atmospheric Sciences, 1998

A new method for the physical retrieval of rain rates from satellite microwave radiometers is pre... more A new method for the physical retrieval of rain rates from satellite microwave radiometers is presented and compared to two other rainfall climatologies derived from satellites. The method is part of a unified ocean parameter retrieval algorithm that is based on the fundamental principles of radiative transfer. The algorithm simultaneously finds near-surface wind speed W, columnar water vapor V, columnar cloud liquid water L, rain rate R, and effective radiating temperature Tu for the upwelling radiation. The performance of the algorithm in the absence of rain is discussed in Wentz [1997], and this paper focuses on the rain component of the algorithm. A particular strength of the unified algorithm is its ability to 'orthogonalize' the retrievals so that there is minimum cross-talk between the retrieved parameters. For example, comparisons of the retrieved water vapor with radiosonde observations show that there is very little correlation between the water vapor retrieval error and rain rate. For rain rates from 1 to 15 mm/h, the rms difference between the retrieved water vapor and the radiosonde value is 5 mm. A novel feature of the rain retrieval method is a beamfilling correction that is based upon the ratio of the retrieved liquid water absorption coefficients at 37 GHz and 19.35 GHz. This ratio decreases by about 40% when heavy and light rain co-exist within the SSM/I footprint as compared to the case of uniform rain. This correction has the effect of increasing the rain rate when the spectral ratio of the absorption coefficients is small. Even with this beamfilling correction, tropical rainfall is still unrealistically low when the freezing level in the tropics (-5 km) is used to specify the rain layer thickness. We restore realism by reducing the assumed averaged tropical rain layer thickness to 3 km, thereby accounting for the existence of warm rain processes in which the rain layer does not extend to the freezing level. Global rain rates are produced for the 1991 through 1994 period from observations taken by microwave radiometers (SSM/I) that are aboard two polar-orbiting satellites. We find that approximately 6% of the SSM/I observations detect measurable rain rates (R > 0.2 mm/h). Zonal averages of the rain rates show the peak at the intertropical convergence zone (ITCZ) is quite narrow in meridional extent and varies from about 7 mm/day in the winter to a maximum 11 mm/day in the summer. Very low precipitation rates (< 0.3 mm/day) are observed in those areas of subsidence influenced by the large semipermanent anticylones. In general, these features are similar to those reported in previously published rain climatologies (Wilheit et al., 1991; Spencer, 1993). However, significant differences do exists between our rain rates and those produced by Spencer (1993). These differences seem to be related to non-precipitating cloud water. wind speed W, columnar water vapor V, columnar cloud liquid water L, rain rate R, and effective radiating temperature Tu for the upwelling radiation. This algorithm is a seamless integration of the Wentz (1997) no-rain algorithm and a newly developed rain algorithm. The algorithm is based on the fundamental principles of radiative transfer and explicitly shows the physical relationship between the inputs (TB) and outputs (W, V, L, R, and Tu). The wind speed retrieval must be constrained to an a priori value for moderate to heavy rain, and Tu must be constrained by a statistical correlation for clear skies and light rain. The other retrieved parameters are unconstrained over the full range of weather conditions. Wentz (1997) discusses the algorithm's performance in the absence of rain, and herein we focus on the rain component of the algorithm. A particular strength of the new method is its ability to 'orthogonalize' the retrievals so that there is minimum cross-talk between the retrieved parameters. With respect to estimating rainfall, it is important to remove the water vapor contribution to the observed brightness temperature. We will present results showing that the error in retrieved water vapor (as determined from radiosonde comparisons) is uncorrelated to the retrieved rain rate. Likewise, the influence of the radiating temperature Tu is separated from the liquid water signal by using the polarization information that is contained in the observations. Because the rain rates are retrieved only after all other significant influences on TB are quantified, the various retrievals can be analyzed for climate relationships between them, with high confidence that there is a minimum of algorithm cross-talk. Conceptually, the rain retrieval involves the following steps. The physics of radiative transfer shows that there is a direct and unique relationship between brightness temperature and the atmospheric transmittance XL of liquid water. In view of this, the first step is to directly retrieve XL along with the other directly observable parameters W, V, and Tu. In the context of rainfall, l:L is related to the columnar water in the rain cloud, and Tu provides information on the height from which the radiation is emanating and whether radiative backscattering by large ice particles is occurring (Spencer, 1986). The retrieval of XL is done by solving a set of simultaneous brightness

Journal of Geophysical Research: Atmospheres, 2007

Temperature change of the lower troposphere (LT) in the tropics (20°S–20°N) during the period 197... more Temperature change of the lower troposphere (LT) in the tropics (20°S–20°N) during the period 1979–2004 is examined using 58 radiosonde (sonde) stations and the microwave‐based satellite data sets of the University of Alabama in Huntsville (UAH v5.2) and Remote Sensing Systems (RSS v2.1). At the 29 stations that make both day and night observations, the average nighttime trend (+0.12 K decade−1) is 0.05 K decade−1 more positive than that for the daytime (+0.07 K decade−1) in the unadjusted observations, an unlikely physical possibility indicating adjustments are needed. At the 58 sites the UAH data indicate a trend of +0.08 K decade−1, the RSS data, +0.15. When the largest discontinuities in the sondes are detected and removed through comparison with UAH data, the trend of day and night releases combined becomes +0.09, and using RSS data, +0.12. Relative to several data sets, the RSS data show a warming shift, broadly occurring in 1992, of between +0.07 K and +0.13 K. Because the sh...

Journal of Climate, 2000

The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) data are used in this study... more The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) data are used in this study as the first passive microwave information from a precessing orbit to reveal diurnal variations of precipitation over the tropical oceans (30ЊS-30ЊN). Data from three Special Sensor Microwave Imagers are combined to help alleviate the aliasing problem caused by the slow diurnal sampling of the TRMM satellite. Annual mean diurnal variations of rainfall in 1998 are presented for 10Њ latitude bands and six regions. The diurnal variation over all the tropical oceans exhibits an amplitude of about Ϯ14% of the mean, and it peaks near dawn (approximately 0400-0700 LST). By latitude band, diurnal variation is most evident in the deep Tropics, while the ratio of the amplitude over the mean is relatively constant over most latitude bands. Other than in the early morning, there are no evident peaks exceeding the error bars for this analysis. By region, the coastal areas where the ITCZ intersects large continents and around the Maritime Continent are dominant. The morning preference of rainfall prevails almost everywhere in the open ocean where the mean rainfall is heavy, even though the amplitude is small compared to that near the continents.