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Patrick J. Michaels
and
David E. Stooksbury

One popular and apocalyptic vision of the world influenced by increasing concentrations of infrared-absorbing trace gases is that of ecological disaster brought about by rapidly rising temperatures, sea level, and evaporation rates. This vision developed from a suite of climate models that have since considerably changed in both their dynamics and their estimates of prospective warming. Observed temperatures indicate that much more warming should already have taken place than predicted by earlier models in the Northern Hemisphere, and that night, rather than day, readings in that hemisphere show a relative warming. A high-latitude polar-night warming or a general night warming could be either benign or beneficial. A large number of plant species show both increased growth and greater water-use efficiency under enhanced carbon dioxide.

An extensive body of evidence now indicates that anthropogenerated sulfate emissions are mitigating some of the warming, and that increased cloudiness as a result of these emissions will further enhance night, rather than day, warming. The sulfate emissions, though, are not sufficient to explain all of the night warming. However, the sensitivity of climate to anthropogenerated aerosols, and the general lack of previously predicted warming, could drastically alter the debate on global warming in favor of less expensive policies.

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Patrick J. Michaels
,
David E. Sappington
, and
David E. Stooksbury

Abstract

Using permafrost boreholes, Lachenbruch and Marshall recently reported evidence for a 2°–4°C warming in North Alaska occurring at some undetermined time during the last century. Popular accounts suggest their findings are evidence for anthropogenic warming caused by trace gases. Analyses of North Alaskan 1000-500 mb thickness onwards back to 1948 indicate that the warming was prior to that date. Relatively sparse thermometric data for the early twentieth century from Jones et al. are too noisy to support any trend since the data record begins in 1910, or to apply to any subperiod of climatic significance. Any warming detected from the permafrost record therefore occurred before the major emissions of thermally active trace gases.

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Pierre G. F. Gérard-Marchant
,
David E. Stooksbury
, and
Lynne Seymour

Abstract

Four algorithms are given, as a first step toward the practical detection of undocumented multiple changepoints. These algorithms are based on the two-phase regression method of Lund and Reeves, as well as the robust method of Lazante. The result of each method is a set that contains statistically detectable changepoints; each candidate is then either independently validated as a changepoint or discarded. This is demonstrated and the methods are compared on artificial data, and then the methods are implemented on streamflow data from the Flint River in southwest Georgia. Most notably, the method based on two-phase regression was able to detect a well-known yet undocumented drop in streamflow from a local drought that no other methods have so far been able to detect.

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David E. Stooksbury
,
Craig D. Idso
, and
Kenneth G. Hubbard

Abstract

Gaps in otherwise regularly scheduled observations are often referred to as missing data. This paper explores the spatial and temporal impacts that data gaps in the recorded daily maximum and minimum temperatures have on the calculated monthly mean maximum and minimum temperatures. For this analysis 138 climate stations from the United States Historical Climatology Network Daily Temperature and Precipitation Data set were selected. The selected stations had no missing maximum or minimum temperature values during the period 1951–80. The monthly mean maximum and minimum temperatures were calculated for each station for each month. For each month 1–10 consecutive days of data from each station were randomly removed. This was performed 30 times for each simulated gap period. The spatial and temporal impact of the 1–10-day data gaps were compared. The influence of data gaps is most pronounced in the continental regions during the winter and least pronounced in the southeast during the summer. In the north central plains, 10-day data gaps during January produce a standard deviation value greater than 2°C about the “true” mean. In the southeast, 10-day data gaps in July produce a standard deviation value less than 0.5°C about the mean. The results of this study will be of value in climate variability and climate trend research as well as climate assessment and impact studies.

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Mark Svoboda
,
Doug LeComte
,
Mike Hayes
,
Richard Heim
,
Karin Gleason
,
Jim Angel
,
Brad Rippey
,
Rich Tinker
,
Mike Palecki
,
David Stooksbury
,
David Miskus
, and
Scott Stephens

The Drought Monitor was started in spring 1999 in response to a need for improved information about the status of drought across the United States. It serves as an example of interagency cooperation in a time of limited resources. The Drought Monitor process also illustrates the creative use of Internet technologies to disseminate authoritative information about drought and to receive regional and local input that is in turn incorporated into the product. This paper describes the Drought Monitor and the interactive process through which it is created.

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