Automated rainwater collector

An automated rain water collector is disclosed to collect a plurality of successive rain water samples, comprised of a reservoir into which rain water is collected and discharged, and a motor-driven turntable which holds a plurality of sample bottles. When the reservoir is filled to a predetermined volume, means, such as a liquid level sensor, actuates a valve to open same and discharge the liquid sample from the reservoir into one of the bottles at a filling station on the turntable. The valve then closes and the turntable rotates to index the next bottle beneath the reservoir at the filling station, and the operation is repeated to fill the latter bottle. When all of the bottles on the turntable have been filled, the indexing means is deactivated and liquid accumulating in the reservoir is diverted to an overflow bottle

Active cloudwater collector

A cloud water collector is disclosed comprised of a sampler duct having a plurality of spaced Teflon strands, in the form of screens, mounted across the conduit at an acute angle facing the open inlet of the conduit. Droplets in a cloud sample are drawn into the conduit by a fan located at the back end of the conduit, impact upon the Teflon strands and are drawn down to the lower ends of the strands, where they drop and the accumulated droplets are diverted to a sample bottle for collection. The cloud water collector can be automated to collect a plurality of successive cloud water samples by an automated sampler containing a reservoir into which cloud water obtained in the cloud water collector is discharged. A motor-driven turntable is provided which holds a plurality of sample bottles. When the reservoir is filled to a predetermined volume, apparatus, such as a liquid level sensor, actuates a valve to open same and discharge the liquid sample from the reservoir into one of the bottles at a filling station on the turntable. The valve then closes and the turntable rotates to index the next bottle beneath the reservoir at the filling station, and the operation is repeated to fill the latter bottle. When all of the bottles on the turntable have been filled, the indexing mechanism is deactivated and liquid accumulating in the reservoir is diverted to an overflow bottle

Seasonal Controls on the Exchange of Carbon and Water in an Amazonian Rain Forest

The long-term resilience of Amazonian forests to climate changes and the fate of their large stores of organic carbon depend on the ecosystem response to climate and weather. This study presents 4 years of eddy covariance data for CO2 and water fluxes in an evergreen, old-growth tropical rain forest examining the forest's response to seasonal variations and to short-term weather anomalies. Photosynthetic efficiency declined late in the wet season, before appreciable leaf litter fall, and increased after new leaf production midway through the dry season. Rates of evapotranspiration were inelastic and did not depend on dry season precipitation. However, ecosystem respiration was inhibited by moisture limitations on heterotrophic respiration during the dry season. The annual carbon balance for this ecosystem was very close to neutral, with mean net loss of 890 ± 220 kg C ha−1 yr−1, and a range of −221 ± 453 (C uptake) to +2677 ± 488 (C loss) kg C ha−1 yr−1 over 4 years. The trend from large net carbon release in 2002 towards net carbon uptake in 2005 implies recovery from prior disturbance. The annual carbon balance was sensitive to weather anomalies, particularly the timing of the dry-to-wet season transition, reflecting modulation of light inputs and respiration processes. Canopy carbon uptake rates were largely controlled by phenology and light with virtually no indication of seasonal water limitation during the 5-month dry season, indicating ample supplies of plant-available-water and ecosystem adaptation for maximum light utilization.Earth and Planetary SciencesEngineering and Applied SciencesOrganismic and Evolutionary Biolog

Vertical Transport Rates in the Stratosphere in 1993 from Observations of CO2, N2O and CH4

Measurements of CO2, N2O and CH4 are analyzed to define hemispheric average vertical exchange rates in the lower stratosphere from November 1992 to October 1993. Effective vertical diffusion coefficients were small in summer, less than or equal to 1 m(exp 2)/sec at altitudes below 25 km; values were similar near the tropopause in winter, but increased markedly with altitude. The analysis suggests possibly longer residence times for exhaust from stratospheric aircraft, and more efficient transport from 20 km to the middle stratosphere, than predicted by many current models. Seasonally-resolved measurements of stratospheric CO2 and N2O provide significant new constraints on rates for global-scale vertical transport

Sources of Carbon Monoxide and Formaldehyde in North America Determined from High-Resolution Atmospheric Data

We analyze the North American budget for carbon monoxide using data for CO and formaldehyde concentrations from tall towers and aircraft in a model-data assimilation framework. The Stochastic Time-Inverted Lagrangian Transport model for CO (STILT-CO) determines local to regional-scale CO contributions associated with production from fossil fuel combustion, biomass burning, and oxidation of volatile organic compounds (VOCs) using an ensemble of Lagrangian particles driven by high resolution assimilated meteorology. In many cases, the model demonstrates high fidelity simulations of hourly surface data from tall towers and point measurements from aircraft, with somewhat less satisfactory performance in coastal regions and when CO from large biomass fires in Alaska and the Yukon Territory influence the continental US. Inversions of STILT-CO simulations for CO and formaldehyde show that current inventories of CO emissions from fossil fuel combustion are significantly too high, by almost a factor of three in summer and a factor two in early spring, consistent with recent analyses of data from the INTEX-A aircraft program. Formaldehyde data help to show that sources of CO from oxidation of CH4 and other VOCs represent the dominant sources of CO over North America in summer.Earth and Planetary Science

Carbon Monitoring System Flux Net Biosphere Exchange 2020 (CMS-Flux NBE 2020)

Here we present a global and regionally resolved terrestrial net biosphere exchange (NBE) dataset with corresponding uncertainties between 2010-2018: Carbon Monitoring System Flux Net Biosphere Exchange 2020 (CMS-Flux NBE 2020). It is estimated using the NASA Carbon Monitoring System Flux (CMS-Flux) top-down flux inversion system that assimilates column CO2 observations from the Greenhouse Gases Observing Satellite (GOSAT) and NASA\u27s Observing Carbon Observatory 2 (OCO-2). The regional monthly fluxes are readily accessible as tabular files, and the gridded fluxes are available in NetCDF format. The fluxes and their uncertainties are evaluated by extensively comparing the posterior CO2 mole fractions with CO2 observations from aircraft and the NOAA marine boundary layer reference sites. We describe the characteristics of the dataset as the global total, regional climatological mean, and regional annual fluxes and seasonal cycles. We find that the global total fluxes of the dataset agree with atmospheric CO2 growth observed by the surface-observation network within uncertainty. Averaged between 2010 and 2018, the tropical regions range from close to neutral in tropical South America to a net source in Africa; these contrast with the extra-tropics, which are a net sink of 2.5±0.3 Gt C/year. The regional satellite-constrained NBE estimates provide a unique perspective for understanding the terrestrial biosphere carbon dynamics and monitoring changes in regional contributions to the changes of atmospheric CO2 growth rate. The gridded and regional aggregated dataset can be accessed at http://doi.org/10.25966/4v02-c391 (Liu et al., 2020).

Carboxylic acids in clouds at a high-elevation forested site in central Virginia

During September 1990 we sampled coarse (>18-μm diameter) and fine (18- to 5.5-μm diameter) droplets and liquid-water content (LWC) in cloud from a tower on a forested ridge top in Shenandoah National Park, Virginia. Cloud-water pH and aqueous- and vapor-phase concentrations of carboxylic acids (HCOOH and CH3COOH) and formaldehyde (HCHO) were measured in parallel over 1- to 1.5-hour intervals. Both size fractions of cloud droplets contained similar concentrations of carboxylic species and H+ during most sampling; most cloud water was in coarse droplets. The pH of coarse (3.27–4.76) and fine (3.22–4.70) droplets coupled with total LWC of 0.04–0.56 g m−3 STP (standard m3 at 0°C and 1 atm) resulted in the partitioning of carboxylic acids primarily in the vapor phase. The observed phase partitioning for CH3COOH was within the uncertainty range of thermodynamic data. However, HCOOH exhibited significant phase disequilibria, which could not be explained by artifacts from variable LWC or from mixing droplets of different acidities. We hypothesize that the large volume of liquid water deposited on the forest canopy interacted with the near-surface cloud leading to apparent disequilibria based on time-integrated samples. HCOOH was selectively depleted relative to CH3COOH in cloud, particularly at higher pH, suggesting rapid removal of HCOOH by cloud-water deposition. We saw no evidence for significant production of HCOOH from the aqueous-phase oxidation of HCHO.Engineering and Applied Science

Carboxylic acids in the rural continental atmosphere over the eastern United States during the Shenandoah Cloud and Photochemistry Experiment

The Shenandoah Cloud and Photochemistry Experiment (SCAPE) was conducted during September 1990 in the rural continental atmosphere at a mountain top site (1014 m) in Shenandoah National Park, Virginia. We report here the extensive set of trace gas measurements performed during clear sky periods of SCAPE, with particular focus on the carboxylic acids, formic, acetic, and pyruvic. Median mixing ratios were 5.4 and 2.1 parts per billion by volume (ppbv) for formic and acetic acid, respectively, and they did not exhibit the diurnal variation characteristic of low-elevation sites. Mixing ratios of formic acid often approached or exceeded 10 ppbv, which are the largest values yet reported for the nonurban troposphere. Over the rural eastern United States, formic and acetic acid appear to have significant nonphotochemical sources. Secondary production from suspected pathways appears to be relatively unimportant. The observed lack of correlation between formic and acetic acid with peroxide species argues against a significant source from permutation reactions of peroxy radicals. In addition, model calculations using the SCAPE data indicate minimal production of carboxylics from olefin/O3 oxidation reactions. The tight correlation (r2 = 0.88) between mixing ratios of formic and acetic acid is strongly suggestive of a commonality in their sources. The seasonal cycle of carboxylic acids in the atmosphere and precipitation over the eastern United States is evidence that combustion emissions are not a principal source of these species. It appears that direct biogenic emissions from vegetation and soils cannot be ruled out as important sources. In particular, the correlation between the seasonal variation of formic and acetic acid and the ambient temperature is consistent with a soil microbial source. Similar conclusions were reached for pyruvic acid, with its mixing ratio ranging 4–266 parts per trillion by volume (pptv) (median = 63) and most likely supported by biogenic emissions and possibly photochemical sources.Engineering and Applied Science