Abstract. Ten data sets coveting the period 1954-2000 are analyzed to show a 1%/yr increase in stratospheric water vapor. The trend has persister for at least 45 years, hence is unl•ely the result of a single event, but rather indicative of long-term climate change. A long-term change in the transport ofwater vapor into the stratosphere is the most probable cause.

Muscle sympathetic nerve activity at rest increases with age in humans. The respective influences of the aging process per se and gender on this increase and whether age and gender effects on muscle sympathetic nerve activity can be identified with plasma norepinephrine concentrations, however, have not been established. To examine these issues, nine young women (aged 24±1 years; mean±SEM), eight young men (aged 26±1 years), seven older women (aged 63±1 years), and eight older men (aged 66±1 years) were studied. All were healthy, normotensive (blood pressure < 140/90 mm Hg), nonobese (<20% above ideal weight), unmedicated, nonsmokers engaged in minimal to recreational levels of chronic physical activity. Arterial blood pressure (manual sphygmomanometry, brachial artery), heart rate, muscle sympathetic nerve activity (peroneal microneurography), and antecubital venous plasma norepinephrine concentrations (radioenzymatic assay) were determined during quiet supine resting conditions. Body weight was higher in men, but there were no age-related differences, whereas estimated body fat (sum of skinfolds) was higher in women and in the older groups (p<0.05). Estimated daily energy expenditure, arterial blood pressure, and heart rate were not different among the groups. Both muscle sympathetic nerve activity burst frequency and burst incidence at rest were progressively higher in the young women, young men, older women, and older men (10±l versus 18±2 versus 25±3 versus 39±5 bursts/min and 16±1 versus 30±4 versus 40±3 versus 61±6 bursts/100 heartbeats, respectively; all p<0.05 versus each other). In contrast, average levels of plasma norepinephrine concentrations were not different among the groups. There was, however, a positive relation between plasma norepinephrine concentrations and muscle sympathetic nerve activity (r=0.65; p<0.0003) when the individual data were pooled. There were no strong or consistent associations between muscle sympathetic nerve activity and any other variable. We conclude that the rise in muscle sympathetic nerve activity with aging in resting humans appears to be independent of age-related differences in ischemic heart disease, obesity, chronic physical activity, or arterial blood pressure, and thus is likely related to some factor associated with the aging process per se. Gender, however, appears to be an important determinant of muscle sympathetic nerve activity at rest in both young and older humans. Finally, the age-and gender-specific influences on muscle sympathetic nerve activity are not necessarily reflected by plasma norepinephrine concentrations. {Hypertension 1993^21:498-503) KEY WORDS • sympathetic nervous system • aging • gender

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5–50 μm), the spectrum of solar radiation reflected by the Earth and its atmosphere (320–2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a “NIST [National Institute of Standards and Technology] in orbit.” CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations

The Cross‐Track Infrared Sounder (CrIS) is a Fourier Transform Michelson interferometer instrument launched on board the Suomi National Polar‐Orbiting Partnership (Suomi NPP) satellite on 28 October 2011. CrIS provides measurements of Earth view interferograms in three infrared spectral bands at 30 cross‐track positions, each with a 3 × 3 array of field of views. The CrIS ground processing software transforms the measured interferograms into calibrated and geolocated spectra in the form of Sensor Data Records (SDRs) that cover spectral bands from 650 to 1095 cm−1, 1210 to 1750 cm−1, and 2155 to 2550 cm−1 with spectral resolutions of 0.625 cm−1, 1.25 cm−1, and 2.5 cm−1, respectively. During the time since launch a team of subject matter experts from government, academia, and industry has been engaged in postlaunch CrIS calibration and validation activities. The CrIS SDR product is defined by three validation stages: Beta, Provisional, and Validated. The product reached Beta and Provisional validation stages on 19 April 2012 and 31 January 2013, respectively. For Beta and Provisional SDR data, the estimated absolute spectral calibration uncertainty is less than 3 ppm in the long‐wave and midwave bands, and the estimated 3 sigma radiometric uncertainty for all Earth scenes is less than 0.3 K in the long‐wave band and less than 0.2 K in the midwave and short‐wave bands. The geolocation uncertainty for near nadir pixels is less than 0.4 km in the cross‐track and in‐track directions.

The experimental objective was to determine whether moderate to severe hypoxemia increases skeletal muscle sympathetic nervous activity (MSNA) in resting humans without increasing venous plasma concentrations of norepinephrine (NE) and epinephrine (E). In nine healthy subjects (20-34 yr), we measured MSNA (peroneal nerve), venous plasma levels of NE and E, arterial blood pressure, heart rate, and end-tidal O2 and CO2 before (control) and during breathing of 1) 12% O2 for 20 min, 2) 10% O2 for 20 min, and 3) 8% O2 for 10 min--in random order. MSNA increased above control in five, six, and all nine subjects during 12, 10, and 8% O2, respectively (P less than 0.01), but only after delays of 12 (12% O2) and 4 min (8 and 10% O2). MSNA (total activity) rose 83 +/- 20, 260 +/- 146, and 298 +/- 109% (SE) above control by the final minute of breathing 12, 10, and 8% O2, respectively. NE did not rise above control at any level of hypoxemia; E rose slightly (P less than 0.05) at one time only with both 10 and 8% O2. Individual changes in MSNA during hypoxemia were unrelated to elevations in heart rate or decrements in blood pressure and end-tidal CO2--neither of which always fell. We conclude that in contrast to some other sympathoexcitatory stimuli such as exercise or cold stress, moderate to severe hypoxemia increases leg MSNA without raising plasma NE in resting humans.

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Sympathetic nervous system reactivity to stress is though to increase with age in humans. We tested this hypothesis by recording postganglionic sympathetic nerve activity to skeletal muscle (MSNA) (peroneal microneurography) and by measuring plasma norepinephrine concentrations (PNE), heart rate, and arterial pressure before (prestress control) and during cognitive challenge (mental arithmetic and colored word test), thermal stress (i.e., the cold pressor test), and exhaustive isometric handgrip exercise (40% of maximum voluntary force)/postexercise ischemia in 15 older (60-74 yr, mean +/- SE = 64 +/- 1) and 15 young (19-30 yr, mean +/- SE = 25 +/- 1) healthy men and women (8 males, 7 females each). The initial prestress control level of MSNA was higher in the older subjects (P < 0.01 vs. young), but there were no significant differences for PNE, heart rate, or arterial pressure. The MSNA and PNE responses to mental stress were small and not different in the two groups. MSNA and PNE increased markedly in response to the cold pressor test and isometric handgrip exercise/post exercise ischemia in both groups. The absolute unit increases in MSNA were similar in the two groups, but the relative (percentage) increases were actually smaller in the older subjects (P < 0.05 vs. young) due to their elevated baseline levels. The stress-evoked increases in arterial pressure were similar in the groups, but the older subjects tended to demonstrate smaller increases in heart rate. In general, no gender differences were noted in either age group. These findings fail to support the long-held concept that stress-induced sympathetic nervous system stimulation becomes exaggerated with age. Thus, sympathetic neural hyperreactivity does not appear to be a fundamental property of the aging process in humans.