Geronimo Creek Observatory

MICROTOPS II is a five-channel, handheld Sun photometer that can be configured to measure total ozone, total water vapor, or aerosol optical thickness at various wavelengths. The instrument measures 10 x 20 x 4.3 cm and weighs 600 g. A principal design goal was the measurement of total ozone to within 1% of ozone measurements made by much larger, heavier, and more expensive Dobson and Brewer spectrophotometers. This goal has been met for a maximum air mass of up to-2.5, as demonstrated by comparisons of MICROTOPS II and its immediate predecessor, Supertops, with Dobson and Brewer instruments at various locations. Conventional interference filters are subject to gradual and unpredictable degradation. MICROTOPS II avoids these problems by using highly stable ultraviolet filters manufactured with an ion deposition process. The 2.4 nm (FWHM) band pass of the UV filters was selected to balance noise and ozone measurement performance. The optical collimators and electronics of the instrument were carefully designed to optimize pointing accuracy, stray light rejection, thermal and long-term stability, signal-to-noise ratio, and data analysis. An internal microcomputer automatically calculates the total ozone column based on measurements at three UV wavelengths, the site's geographic coordinates, and universal time, altitude, and pressure. The coordinates can be entered manually or by a Global Positioning System (GPS) receiver. A built-in pressure transducer automatically measures pressure. MICROTOPS II saves in nonvolatile memory up to 800 scans of the raw and calculated data. Measurements can be read from a liquid crystal display or transferred to an external computer.

The Global Learning and Observations to Benefit the Environment (GLOBE) Program is an international network of schools in 71 countries that monitors up to 20 environmental parameters. Recently GLOBE added a haze-monitoring program to its measurement protocols. This network has the potential of providing important data about changes in the aerosol optical depth of the atmosphere caused by weather fronts, industrial and automobile pollution, and smoke from forest and brush fires and volcanic eruptions. Initially, monitoring will be conducted with an inexpensive, single-channel (520 nm) sun photometer. Unlike conventional sun photometers that use interference filters that are subject to unpredictable and rapid degradation, the GLOBE instrument uses a common light-emitting diode (LED) as a spectrally selective detector. Annual calibrations of two LED sun photometers at Mauna Loa Observatory since 1992 show that these instruments have insignificant degradation when compared to filter sun photometers. Some 175 prototype versions of a kit LED sun photometer have been assembled and tested by students from 16 countries at the University of the Nations and by more than 130 high school teachers in various pilot studies. These studies have demonstrated that even inexperienced students and teachers can quickly assemble a sun photometer from a kit of parts and perform a reliable Langley calibration. The pilot studies have also demonstrated that sun photometery provides a convenient means for allowing students to perform hands-on science while they learn about various topics in history, electronics, algebra, statistics, graphing, and meteorology.

One potential drawback of the excitation geometry presented here is that the metal-coated gratings used in dye lasers have relatively low damage thresholds and hence are susceptible to damage by the pump laser. However, this is not a serious limitation especially in dye laser systems of the oscillator amplifier type, in which the oscillator is pumped with a small amount of pump energy to obtain a narrow spectral linewidth. In addition, the large magnification of the pump beam on the grating surface that is due to the grazing incidence results in a considerable reduction in power density. In our laser system we have not encountered grating damage over several weeks of operation. For oscillator amplifier systems, it is desirable to obtain emission with good spatial quality from the oscillator and in this respect the present pumping arrangement may be more attractive than off-axis pumping because of a better match of the pump laser and the dye laser modes. To summarize, a new pumping geometry for a grazingincidence grating dye laser has been presented in which true longitudinal pumping is achieved by coupling the pump beam to the dye laser resonator by way of zero-order diffraction from the grating. Laser emission with good spatial quality was obtained from a dye laser based on this configuration.

A statistical analvsis of total column ozone observations during the total eclipse of July 11, 1991, disclosed a series of fluctuations in the ozonosphere following totality.. The principle fluctuation, which began 700 seconds after third contact, has an unsmoothed, peak-topeak amplitude of 5 m-atm-cm. This amounts to 1.7% of the total ozone column 2000 seconds after third contact. This fluctuation was preceded by one and followed by two fluctuations with reduced amplitude.

C ontemporary science has its roots in direct recognition. Although some are rethe achieveinents of amateur scien-tired, others are taxi drivers, photographers, tists of centuries past. Although they civil servants, pilots, or missionaries, the lacked what we would define as formal sci-latter group having an especially impresentific training, they deciphered the basic laws of physics and principles of chemistry. They invented instruments. And they discovered, documented, sketched, and painted planets, comets, fossils, and species. An editorial in a leading science journal once proclaimed an end to amateur science: "Modern science can no longer be done by gifted amateurs with a magnifying glass, copper wires, and jars filled with alcohol" (1). I grinned as I read these words. For then as now there's a lox magnifier in my pocket, spools of copper wire on my work bench, and a nearby jar of methanol for cleaning the ultraviolet filters in my homemade solar ultraviolet and ozone spectroradiometers. Yes, modem science uses considerably more sophisticated methods and instruments than in the past. And so do we amateurs. When we cannot afford the newest scientific instrument, we

A report (Kerr and McElroy, 1993) about record high solar UV-B irradiance at 300 nm at Toronto in 1993 suggests that global ozone decline may have caused increasexl UV-B elsewhere. This suggestion is consistent with observations of increased UV-B associated with record low ozone near and around Seguin, Texas, during the summer of 1993. A sharp drop in ozone occurred during late June, and on 23 June total ozone fell to 230 Dobson units, which is 25.7% below the Nimbus-7/TOMS observed mean for June 20-24 from 1979 to 1991 (310 DU). Direct UV-B at 300 nm was the highest since ground observations were begun in February 1990. During July and August 1993, the mean total ozone was, respectively, 13% and 10.755 lower than during July and August 1990. When the Sun was not obscured by clouds or haze during July and August 1993, the mean direct irradiance at 300 run was, respectively, 18.1% and 13.4 % higher than during July and August 1990. of Mexico and moved toward the developing trough over South Central Texas. Arlene made landfall on the lower Texas coast on 20 June and drifted westward, leaving in its 0.6 AOT Pinatubo eruption ß ß 14 e ß ß ee et 0.4 ß % **. 12

We read with interest the recent study titled "Neurologic Symptoms in Licensed Private Pesticide Applicators in the Agricultural Health Study" (Kamel et al. 2005). Although this was a hypothesis-generating study, the authors speculated regarding moderate exposure and associations with neurologic symptoms. Substantiation of hypotheses requires meaningful metrics of exposure and effect, and depends on exclusion and analysis of competing hypotheses for the observations. In our opinion, the article by Kamel et al. falls seriously short in several regards and requires additional data in order to provide credible and defensible conclusions. Kamel et al. (2005) analyzed a number of symptoms in those "ever" experiencing one of 23 self-reported symptoms in the preceding 12 months. The biologic significance of the outcome "symptom count" is unknown; also, "multiple symptoms" is not a definable disease or illness. The fact that private applicators report headache, nausea, and fatigue does not establish that each is of neurologic origin, particularly given the physical requirements of farming. Indeed, results of the questions used by Kamel et al. (2005) have been shown to agree poorly with objective tests of neurologic function (Lundberg et al. 1997). Further, Kamel et al. limited the analyses to a single episode rather than symptoms that were reported more than once per year (Kamel et al. (2005); Table 2). As a crosssectional analysis, the data do not permit assessment of the temporal relationship between exposure and symptom onset, and no consideration was given to the transient nature of the reported symptoms. Thus, although the nature of the analysis implies some sort of persistent neurologic condition underlying the reporting of symptoms, no such condition can be established from intermittent symptoms of indeterminate etiology. In addition to other potential causes for these symptoms, researchers have warned about the role of psychosocial factors in the reporting of non-specific symptoms. According to Spurgeon et al. (1996), Many occupational and environmental health hazards present as an increased reporting of nonspecific symptoms such as headache, backache, eye and respiratory irritation, tiredness, memory problems, and poor concentration. The pattern and number of such symptoms is surprisingly constant from hazard to hazard suggesting that common psychological and social factors, not directly related to the exposure may be involved.

Light-emitting diodes (LED), which are designed as quasimonochromatic light sources, can also function as spectrally selective photodiodes. This provides a new kind of photosynthetically active radiation (PAR) sensor that is inexpensive and has much better stability over time than interference filters used in some PAR sensors. The action spectrum of photosynthesis in green plants has principle peaks in the blue and red regions. LED with response peaks in the UV-A (380 nm) and red (620 nm) regions have been used to measure PAR at or near solar noon in an ongoing study begun on 30 April 1996. The sum of the signals from the two LED is highly correlated with measurements by a calibrated filterless PAR sensor (Apogee QSO; Logan, Utah) from 13 September 1997 to 16 January 2002 (r 2 5 0.97). The sum of the LED signals is also highly correlated with measurements by a calibrated filter PAR sensor (LI-COR LI-190SA; Lincoln, Nebraska) from 20 April 1998 to 16 January 2002 (r 2 5 0.97). Thus, pairs of spectrally selective LED can function as PAR detectors in economical PAR radiometers. The separate 380 and 620 nm responses also permit an assessment of the differential impact of aerosol events on blue and red PAR and phototropic radiation.

CHaMbers, and david r. brooks total column water vapor, integrated water vapor (IWV), precipitable water (PW), and integrated precipitable water (IPW). Each of these phrases specifies the depth of liquid water that would result if all of the water vapor in a vertical column through the atmosphere were brought to the surface at standard temperature and pressure. METHODS OF MEASURING PRECIPITABLE WATER. Fowle (1912) devised one of the earliest methods for measuring PW. He employed a prism spectrometer to measure the intensity of direct sunlight at the water vapor absorbing bands at 1.13 and 1.47 μm, and nearby nonabsorbing bands. Fowle's method led to the development of many kinds of spectrometers and sun photometers that measured PW, most of which employed pairs of silicon photodiodes and interference filters, one being preferentially transparent to the water vapor absorbing band at about 940 nm and the second transmitting a nearby reference band near 860 or 1,000 nm. For example, Volz (1974) developed a handheld filter sun photometer that measured PW using a pair of appropriately filtered photodiodes. Interference filters are less costly than spectrometers, but they are subject to unpredictable drift. Mims (1992) addressed this problem by developing a filterless sun photometer, which uses light-emitting diodes (LEDs) as spectrally selective photodiodes and has provided ongoing measurements of PW over south-central Texas since February 1990. Brooks et al. (2007) used LEDs in an inexpensive PW sun photometer for the GLOBE program. Water vapor has been measured since 1930 by instrumented sounding balloons (Pettifer 2009). PW is determined by summing the mixing ratio (grams of water vapor per kilograms of dry air) as the balloon ascends. Accuracy is affected by the performance of the temperature and humidity sensors, the solar MEASURING PW WITH IR DETECTORS AND THERMOMETERS. Both clouds and water vapor absorb and re-emit radiation in discrete bands across the infrared spectrum. This permits infrared radiometers, including those configured as IR thermometers, to detect clouds, which are warmer than the clear sky, and water vapor (Sloan et al. 1955). Werner (1973) described the use of an infrared thermometer to detect clouds. The thermometer's IR sensor was a thermistor bolometer that was responsive to 9.5-11.5 μm. Today IR thermometry is used to detect the presence and temperature of clouds for

Eos reported on June 28,1994, that the AGU Council has reaffirmed for the second time a statement on "Creationism" first adopted in December 1981. The brief state ment opposes "...all efforts to require or promote the teaching of creationism or any other religious tenets as science." The state ment offers no definition of creationism. The AGU Council's rejection of "creation

The forward scattering of sunlight by atmospheric aerosols causes a bright glow to appear around the Sun. This phenomenon, the simplest manifestation of the solar corona, is called the solar aureole. Simple methods can be used to photograph the solar aureole with conventional and digital cameras. Aureole images permit both a visually qualitative and an analytically quantitative comparison of aureoles caused by dust, smoke, haze, pollen, and other aerosols. Many hundreds of aureole photographs have been made at Geronimo Creek Observatory in Texas, including a regular time series since September 1998. These images, and measurements extracted from them, provide an important supplement to studies of atmospheric aerosols.

Viable fungal spores are present in smoke from distant biomass fires. This finding has potentially important implications for prescribed burning, agricultural management and public health. While attempting to find fungal spores in dust blown from China to Texas, one of us (S.A.M.) discovered that smoke from Yucatan contains viable bacteria and fungal spores, including the genera Alternaria, Cladosporium, Fusariella and Curvularia. There was a high correlation (r 2 ¼ 0:78) of spores and coarse carbon particles collected on microscope slides during 13 days of the 2002 smoke season. To eliminate possible contamination by local spores, an air sampler was flown from a kite at a Texas Gulf Coast beach during and after the 2003 smoke season on days when the NOAA back trajectory showed air arriving from Yucatan. Fifty-two spores and 19 coarse black carbon particles (>2.5 mm) were collected during a 30-min kite flight on the smoke day and 12 spores and four carbons on the day without smoke. We have found spores in smoke from an Arizona forest fire and in Asian smoke at Mauna Loa Observatory, Hawaii. We have tested these findings by burning dried grass, leaves, twigs and flood detritus. The smoke from all test fires contained many spores.

W ater vapor is the constituent of the atmosphere that is most responsible for weather, the hydrological cycle, and the maintenance of Earth's temperature within a range that supports life as we know it (Mockler 1995). Furthermore, water vapor condensed on sulfate and other hygroscopic aerosols can significantly increase the aerosol optical thickness of the atmosphere (Tang 1996). The direct and indirect influence of water vapor on weather, climate, and the environment is so important that there is significant interest in techniques for inferring its vertical distribution and its total abundance in a vertical column through the atmosphere. The latter parameter, the measurement of which is the central subject of this paper, is variously described as  A $20 infrared thermometer pointed at the cloud-free zenith sky can measure precipitable water vapor about as well as a sun photometer, and it can do so during the day or night. Readings from this infrared thermometer (foreground) ...