University of New Hampshire

About: University of New Hampshire is a education organization based out in Durham, New Hampshire, United States. It is known for research contribution in the topics: Population & Solar wind. The organization has 9379 authors who have published 24025 publications receiving 1020112 citations. The organization is also known as: UNH.

Photochemistry in biomass burning plumes and implications for tropospheric ozone over the tropical South Atlantic

Abstract: Photochemistry occuring in biomass burning plumes over the tropical south Atlantic is analyzed using data collected during the Transport and Atmospheric Chemistry Near the Equator-Atlantic aircraft expedition conducted during the tropical dry season in September 1992 and a photochemical point model. Enhancement ratios (ΔY/ΔX, where Δ indicates the enhancement of a compound in the plume above the local background mixing ratio, Y are individual hydrocarbons, CO, O3, N2O, HNO3, peroxyacetyl nitrate (PAN), CH2O, acetone, H2O2, CH3OOH, HCOOH, CH3COOH or aerosols and X is CO or CO2) are reported as a function of plume age inferred from the progression of Δnon-methane hydrocarbons/ΔCO enhancement ratios. Emission, formation, and loss of species in plumes can be diagnosed from progression of enhancement ratios from fresh to old plumes. O3 is produced in plumes over at least a 1 week period with mean ΔO3/ΔCO = 0.7 in old plumes. However, enhancement ratios in plumes can be influenced by changing background mixing ratios and by photochemical loss of CO. We estimate a downward correction of ∼20% in enhancement ratios in old plumes relative to ΔCO to correct for CO loss. In a case study of a large persistent biomass burning plume at 4-km we found elevated concentrations of PAN in the fresh plume. The degradation of PAN helped maintain NOx mixing ratios in the plume where, over the course of a week, PAN was converted to HNO3. Ozone production in the plume was limited by the availability of NOx, and because of the short lifetime of O3 at 4-km, net ozone production in the plume was negligible. Within the region, the majority of O3 production takes place in air above median CO concentration, indicating that most O3 production occurs in plumes. Scaling up from the mean observed ΔO3/ΔCO in old plumes, we estimate a minimum regional O3 production of 17×1010molecules O3 cm−2 s−1. This O3 production rate is sufficient to fully explain the observed enhancement in tropospheric O3 over the tropical South Atlantic during the dry season.

Analysis of aircraft and satellite measurements from the Intercontinental Chemical Transport Experiment (INTEX-B) to quantify long-range transport of East Asian sulfur to Canada

Abstract: We interpret a suite of satellite, aircraft, and ground-based measurements over the North Pacific Ocean and western North America during April-May 2006 as part of the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign to understand the implica- tions of long-range transport of East Asian emissions to North America. The Canadian component of INTEX-B included 33 vertical profiles from a Cessna 207 aircraft equipped with an aerosol mass spectrometer. Long-range transport of organic aerosols was insignificant, contrary to expectations. Measured sulfate plumes in the free tropo- sphere over British Columbia exceeded 2µg/m 3 . We up- date the global anthropogenic emission inventory in a chem- ical transport model (GEOS-Chem) and use it to interpret the observations. Aerosol Optical Depth (AOD) retrieved from two satellite instruments (MISR and MODIS) for 2000-2006 are analyzed with GEOS-Chem to estimate an annual growth in Chinese sulfur emissions of 6.2% and 9.6%, respectively. Analysis of aircraft sulfate measurements from the NASA DC-8 over the central Pacific, the NSF C-130 over the east Pacific and the Cessna over British Columbia indicates most Asian sulfate over the ocean is in the lower free troposphere (800-600 hPa), with a decrease in pressure toward land due to orographic effects. We calculate that 56% of the mea- sured sulfate between 500-900 hPa over British Columbia is due to East Asian sources. We find evidence of a 72- 85% increase in the relative contribution of East Asian sul- fate to the total burden in spring off the northwest coast of the United States since 1985. Campaign-average simulations indicate anthropogenic East Asian sulfur emissions increase mean springtime sulfate in Western Canada at the surface by 0.31µg/m 3 ( 30%) and account for 50% of the overall re- gional sulfate burden between 1 and 5 km. Mean measured daily surface sulfate concentrations taken in the Vancouver area increase by 0.32µg/m 3 per 10% increase in the simu- lated fraction of Asian sulfate, and suggest current East Asian emissions episodically degrade local air quality by more than 1.5µg/m 3 .

Ecosystem warming extends vegetation activity but heightens vulnerability to cold temperatures

Abstract: Shifts in vegetation phenology are a key example of the biological effects of climate change1–3. However, there is substantial uncertainty about whether these temperature-driven trends will continue, or whether other factors—for example, photoperiod—will become more important as warming exceeds the bounds of historical variability4,5. Here we use phenological transition dates derived from digital repeat photography6 to show that experimental whole-ecosystem warming treatments7 of up to +9 °C linearly correlate with a delayed autumn green-down and advanced spring green-up of the dominant woody species in a boreal Picea–Sphagnum bog. Results were confirmed by direct observation of both vegetative and reproductive phenology of these and other bog plant species, and by multiple years of observations. There was little evidence that the observed responses were constrained by photoperiod. Our results indicate a likely extension of the period of vegetation activity by 1–2 weeks under a ‘CO2 stabilization’ climate scenario (+2.6 ± 0.7 °C), and 3–6 weeks under a ‘high-CO2 emission’ scenario (+5.9 ± 1.1 °C), by the end of the twenty-first century. We also observed severe tissue mortality in the warmest enclosures after a severe spring frost event. Failure to cue to photoperiod resulted in precocious green-up and a premature loss of frost hardiness8, which suggests that vulnerability to spring frost damage will increase in a warmer world9,10. Vegetation strategies that have evolved to balance tradeoffs associated with phenological temperature tracking may be optimal under historical climates, but these strategies may not be optimized for future climate regimes. These in situ experimental results are of particular importance because boreal forests have both a circumpolar distribution and a key role in the global carbon cycle11. Experimental whole-ecosystem warming treatments of a Picea–Sphagnum peat bog reveal the likely phenological consequences of future temperature increases that exceed those of historical climate regimes.

A global view of epistasis.

Abstract: Epistasis is a phenomenon whereby the effects of a given gene on a biological trait are masked or enhanced by one or more other genes. A new study documents epistasis among 890 metabolic genes in yeast, providing one of the largest data sets of its kind in any model organism.