Determination of trace compounds and artifacts in nitrogen background measurements by proton transfer reaction time-of-flight mass spectrometry under dry and humid conditions

A qualitative analysis was applied for the determination of trace compounds at the parts per trillion in volume (pptv) level in the mass spectra of nitrogen of different qualities (5.0 and 6.0) under dry and humid conditions. This qualitative analysis enabled the classification and discovery of hundreds of new ions (e.g., [Sx]H+ species) and artifacts such as parasitic ions and memory effects and their differentiation from real gas impurities. With this analysis, the humidity dependency of all kind of ions in the mass spectrum was determined. Apart from the inorganic artifacts previously discovered, many new organic ions were assigned as instrumental artifacts and new isobaric interferences could be elucidated. From 1140 peaks found in the mass range m/z 0–800, only 660 could be analyzed due to sufficient intensity, from which 463 corresponded to compounds. The number of peaks in nitrogen proton transfer reaction (PTR) spectra was similarly dominated by nonmetallic oxygenated organic compounds (23.5%) and hydrocarbons (24.1%) Regarding only gas impurities, hydrocarbons were the main compound class (50.2%). The highest contribution to the total ion signal for unfiltered nitrogen under dry and humid conditions was from nonmetallic oxygenated compounds. Under dry conditions, nitrogen-containing compounds exhibit the second highest contribution of 89% and 96% for nitrogen 5.0 and 6.0, respectively, whereas under humid conditions, hydrocarbons become the second dominant group with 69% and 86% for nitrogen 5.0 and 6.0, respectively. With the gathered information, a database can be built as a tool for the elucidation of instrumental and intrinsic gas matrix artifacts in PTR mass spectra and, especially in cases, where dilution with inert gases plays a significant role

Space Weather Effects on Mid-Latitude HF Propagation Paths: Observations and a Data-Driven D-Region Model

A two-pronged study is under way to improve understanding of the D region response to space weather and its effects on HF propagation. One part, the HF Investigation of D region Ionospheric Variation Experiment (HIDIVE), is designed to obtain simultaneous, quantitative propagation and absorption data from an HF signal monitoring network along with solar X-ray flux from the NOAA GOES satellites. Observations have been made continuously since late December 2002 and include the severe disturbances of October–November 2003. GOES satellite X-ray observations and geophysical indices are assimilated into the Data-Driven D Region (DDDR) electron density model developed as the second part of this project. ACE satellite proton observations, the HIDIVE HF observations, and possibly other real-time space weather data will be assimilated into DDDR in the future. Together with the Ionospheric Forecast Model developed by the Space Environment Corporation, DDDR will provide improved specification of HF propagation and absorption characteristics when supplemented by near-real-time propagation observations from HIDIVE

Dayside midlatitude ionospheric response to storm time electric fields: A case study for 7 September 2002

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95503/1/jgra21582.pd

Sugarbeet Production Under Reduced Tillage Prospects And Problems

A study was initiated in the fall of 1977 to obtain base line data on the applicability of reduced tillage sugarbeet production in the Red River Valley. Three reduced tillage systems were compared to a conventional system which consisted of fall plow plus secondary tillage. Results indicated warmer early spring soil temperatures, better seedling emergence, lower ground-level wind speed and no significant yield loss under reduced tillage as compared to the conventional system

Theoretical Study of the Effect of Ionospheric Return Currents on the Electron Temperature

An electron heat flow can occur in a partially ionized plasma in response to either an electron temperature gradient (thermal conduction) or an electron current (thermoelectric heat flow). The former process has been extensively studied, while the latter process has received relatively little attention. Therefore a time-dependent three-dimensional model of the high-latitude ionosphere was used to study the effect of field-aligned ionospheric return currents on auroral electron temperatures for different seasonal and solar cycle conditions as well as for different upper boundary heat fluxes. The results of this study lead to the following conclusions: (1) The average, large-scale, return current densities, which are a few microamps per square meter, are too small to affect auroral electron temperatures. (2) Current densities greater than about 10−5 A m−2 are needed for thermoelectric heat flow to be important. (3) The thermoelectric effect displays a marked solar cycle and seasonal dependence. (4) Thermoelectric heat transport corresponds to an upward flow of electron energy. (5) This energy flow can be either a source or sink of electron energy, depending on the altitude and geophysical conditions. (6) Thermoelectric heat transport is typically a sink above 300 km and acts to lower ambient electron temperatures by as much as 2000 K for field-aligned return current densities of the order of 5 × 10−5 A m−2. For this case, the electron temperature decreases with altitude above 300 km with a gradient that can exceed 1 K km−1. Also, the electron temperature can drop below both the ion and neutral temperatures in the upper F region owing to thermoelectric cooling. (7) A downward magnetospheric heat flux in combinations with an upward thermoelectric heat flux can produce steep positive electron temperature gradients in the topside ionosphere

Nitrogen placement, row spacing, and water management for furrow-irrigated field corn

Banding and sidedressing nitrogen (N) fertilizer on a never-irrigated side of a row of corn (Zea mays L.) were hypothesized to maintain yield and decrease nitrate leaching. In a two—year ?eld study on a Portneuf silt loam (Durinodic Xeric Haplocalcid) in southern Idaho, we evaluated effects on yield and N uptake of 1) urea placement (broadcast pre-plant vs. band at planting), 2) row spacings (30-in vs. an offset 22—in spacing in which every pair of 22-—in rows was positioned close to a furrow rather than each row on a bed center), and 3) water management. Our water management, termed irrigated furrow positioning, consisted of every- second furrow irrigation in which we applied water to either a) the same or b) the Opposite side of the row with successive irrigations, the latter called alternating furrow irrigation. At season’s end, we harvested 20 ft of row at three locations in each plot for silage and at three other locations for grain. Grain yield was not affected by the positioning of the irrigated furrow. However, averaged across years, grain yield from 22-in rows was 113 bu acre-1 from banded plots, 5% greater (P<0.05) than broadcast plots. Two-year average grain yield from 30-in rows was 107 bu acre-1, with no difference between banding and broadcasting. In the second year, N uptake in grain averaged across row spacings was 72.3 lb acre-l from banded plots and 65.5 lb acre-l from broadcast plots (P<0.01). Silage yield increased up to 26% and N uptake in silage increased up to 21% from banding, compared to broadcasting, where we irrigated the same furrow in the study’s second year. In both years, grain and silage yield and N uptake in grain and silage were similar or greater where urea was banded on one side of a row rather than broadcast

Nitrogen placement, row spacing, and water management for furrow-irrigated field corn

Banding and sidedressing nitrogen (N) fertilizer on a never-irrigated side of a row of corn (Zea mays L.) were hypothesized to maintain yield and decrease nitrate leaching. In a two—year ?eld study on a Portneuf silt loam (Durinodic Xeric Haplocalcid) in southern Idaho, we evaluated effects on yield and N uptake of 1) urea placement (broadcast pre-plant vs. band at planting), 2) row spacings (30-in vs. an offset 22—in spacing in which every pair of 22-—in rows was positioned close to a furrow rather than each row on a bed center), and 3) water management. Our water management, termed irrigated furrow positioning, consisted of every- second furrow irrigation in which we applied water to either a) the same or b) the Opposite side of the row with successive irrigations, the latter called alternating furrow irrigation. At season’s end, we harvested 20 ft of row at three locations in each plot for silage and at three other locations for grain. Grain yield was not affected by the positioning of the irrigated furrow. However, averaged across years, grain yield from 22-in rows was 113 bu acre-1 from banded plots, 5% greater (P<0.05) than broadcast plots. Two-year average grain yield from 30-in rows was 107 bu acre-1, with no difference between banding and broadcasting. In the second year, N uptake in grain averaged across row spacings was 72.3 lb acre-l from banded plots and 65.5 lb acre-l from broadcast plots (P<0.01). Silage yield increased up to 26% and N uptake in silage increased up to 21% from banding, compared to broadcasting, where we irrigated the same furrow in the study’s second year. In both years, grain and silage yield and N uptake in grain and silage were similar or greater where urea was banded on one side of a row rather than broadcast

Observations of the Diurnal Dependence of the High-Latitude \u3ci\u3eF\u3c/i\u3e Region Ion Density by DMSP Satellites

Data from the DMSP F2 and F4 satellites for the period December 5-10, 1979, have been used to study the diurnal dependence of the high-latitude ion density at 800-km altitude. A 24-hour periodicity in the minimum orbital density (MOD) during a crossing of the high-latitude region is observed in both the winter and summer hemispheres. The phase of the variation in MOD is such that it has a minimum during the 24-hour period between 0700 and 0900 UT. Both the long term variation of the high-latitude ion density on a time scale of days, and the orbit by orbit variations at the same geomagnetic location in the northern (winter) hemisphere for the magnetically quiet time period chosen show good qualitative agreement with the diurnal dependence predicted by a theoretical model of the ionospheric density at high latitudes under conditions of low convection speeds (Sojka et al., 1981a)