Sounding Rocket Observations of Active Region Soft X-Ray Spectra Between 0.5 and 2.5 nm Using a Modified SDO/EVE Instrument

Spectrally resolved measurements of individual solar active regions (ARs) in the soft X-ray (SXR) range are important for studying dynamic processes in the solar corona and their associated effects on the Earth’s upper atmosphere. They are also a means of evaluating atomic data and elemental abundances used in physics-based solar spectral models. However, very few such measurements are available. We present spectral measurements of two individual ARs in the 0.5 to 2.5 nm range obtained on the NASA 36.290 sounding rocket flight of 21 October 2013 (at about 18:30 UT) using the Solar Aspect Monitor (SAM), a channel of the Extreme Ultaviolet Variability Experiment (EVE) payload designed for underflight calibrations of the orbital EVE on the Solar Dynamics Observatory (SDO). The EVE rocket instrument is a duplicate of the EVE on SDO, except the SAM channel on the rocket version was modified in 2012 to include a freestanding transmission grating to provide spectrally resolved images of the solar disk with the best signal to noise ratio for the brightest features, such as ARs. Calibrations of the EVE sounding rocket instrument at the National Institute of Standards and Technology Synchrotron Ultraviolet Radiation Facility (NIST/SURF) have provided a measurement of the SAM absolute spectral response function and a mapping of wavelength separation in the grating diffraction pattern. We discuss techniques (incorporating the NIST/SURF data) for determining SXR spectra from the dispersed AR images as well as the resulting spectra for NOAA ARs 11877 and 11875 observed on the 2013 rocket flight. In comparisons with physics-based spectral models using the CHIANTI v8 atomic database we find that both AR spectra are in good agreement with isothermal spectra (4 MK), as well as spectra based on an AR differential emission measure (DEM) included with the CHIANTI distribution, with the exception of the relative intensities of strong Fe?xvii lines associated with \(2p^{6}\)–\(2p^{5}3{s}\) and \(2p^{6}\)–\(2p^{5}3{d}\) transitions at about 1.7 nm and 1.5 nm, respectively. The ratio of the Fe?xvii lines suggests that the AR 11877 is hotter than the AR 11875. This result is confirmed with analysis of the active regions imaged by X-ray Telescope (XRT) onboard Hinode.     

The history and architecture of lacustrine depositional systems in the northern Lake Michigan basin

The post-glacial history of the Great Lakes has involved changes in lake levels that are equivalent in vertical extent to the Pleistocene changes in global sea level and changes in sediment accumulation by at least two orders of magnitude. In the sediments of the northern Lake Michigan basin, these radical changes in base level and sediment supply are preserved in detailed records of changing depositional environment and the impact of these changes on depositional architecture. The seismic sequences of the sediment fill previously described in Lake Huron have been carried into northern Lake Michigan and used to map the history and architecture of basinal deposition. As the Laurentide Ice Sheet retreated northward in the early Holocene, it opened progressively deeper channels to the east that allowed the larger lakes to drain through the North Channel, Huron, and Georgian Bay basins. At the end of the Main Algonquin highstand, about 10,200 (radiocarbon) yrs ago, the eastern drainage passage deepened in a series of steps that defined four seismic sequences and lowered lake levels by over 100 m. Near the same time a new source of sediment and meltwaters poured across the Upper Peninsula of Michigan and into the northern Lake Michigan basin from the Superior basin ice lobe. A marked increase in deposition is seen first in the northern part of the study area, and slightly later in the Whitefish Fan area at the southern end of the study area. Accumulation rates in the area gradually decreased even as lake levels continued to fall. Drainage directly from the Superior basin ended before the beginning of the main Mattawa phase about 9,200 (radiocarbon) yrs ago.Although individual lowstand systems tracts are at the most a few hundred yrs in duration, their geometries and seismic character are comparable to marine systems tracts associated with sea level falls of similar magnitudes. In some of the thicker lowstand deposits a second order cyclicity in sedimentation can be detected in the high resolution seismic records.     

Hybrid GPS + GLONASS

The hybridization of GPS with GLONASS has formed a first stage in GNSS development. We examine the performance of the hybrid system in the position domain for both code and carrier phase cases. Several major differences exist between GPS and GLONASS; most significant is GLONASS's signal frequency diversity, which can lead to measurement bias, particularly so when a pair of receivers are operating at different temperatures. Unless signal frequency diversity is addressed either on-receiver or at the data processing stage, positioning errors can occur at the centimeter level. We outline the difficulties of combining observations from the two systems and discuss how these may be overcome. ? 1999 John Wiley & Sons, Inc.     

Calculating downward longwave radiation under clear and cloudy conditions over a tropical lowland forest site: an evaluation of model schemes for hourly data

Field measurements of radiation fluxes—notably downwelling longwave radiation flux (LW flux)—are as yet rare or nonexistent outside a very select number of sites in the tropics. Data gaps can only be filled through the use of estimation schemes based on measurements of other meteorological variables, and there is a need for recommendations on best practice in this area. We selected 18 contrasting semi-empirical estimation schemes for downward longwave radiation, based on air emissivities, combined with six different sky cover estimation schemes and compared the expected longwave flux with hourly observations from a flux tower at Caxiuan? in Brazil. Of all schemes tested, the Dilley–Kimball emissivity scheme combined with Kasten and Czeplak’s sky cover scheme during the day and Dilley and O’Brien’s model B scheme at night proved to be the most reliable, yielding estimates of LW flux generally within 20?W/m² of measurements across all time points.     

Entanglements of marine mammals and seabirds in central California and the north-west coast of the United States 2001-2005

Entanglement records for seabirds and marine mammals were investigated for the period 2001-2005. The entanglement records were extracted from databases maintained by seven organizations operating along the west coast of the United States of America. Their programmes included beach monitoring surveys, rescue and rehabilitation and regional pinniped censuses. Records of 454 entanglements were documented in live animals and in carcasses for 31 bird species and nine marine mammal species. The most frequently entangled species were Common Murres, Western Gulls and California sea lions. The entanglement materials identified were primarily fishing related. Entanglements were recorded every year suggesting that although the incidence level differs annually, entanglement is a persistent problem. It is recommended that each programme records details in standardized categories to determine entanglement material sources. Numbers of entanglements observed during these surveys are likely to be a conservative view of the actual entanglement rate taking place at sea.     

Geochemistry of the thermal springs of Mount Taftan,southeastern Iran

Thermal and cold water chemistry from the southern flank of Mount Taftan was investigated in order to discriminate among hydrochemical facies, isotopic characteristics, geothermal reservoir and identify the major geochemical processes that affect water composition.     

Sensitivity of the Himalayan Hydrology to Land-Use and Climatic Changes

Land-use and climatic changes are ofmajor concerns in the Himalayan region because oftheir potential impacts on a predominantlyagriculture-based economy and a regional hydrologydominated by the monsoons. Such concerns are notlimited to any particular basin but exist throughoutthe region including the downstream plains. As arepresentative basin of the Himalayas, the Kosi Basin(54,000 km²) located in the mountainous area ofthe central Himalayan region was selected as a studyarea. We used water balance and distributeddeterministic modeling approaches to analyze thehydrologic sensitivity of the basin to projectedland-use, and potential climate change scenarios.Runoff increase was higher than precipitation increasein all the potential precipitation change scenariosapplying contemporary temperature. The scenario ofcontemporary precipitation and a rise in temperatureof 4 °C caused a decrease in runoff bytwo to eight percent depending upon the areasconsidered and models used. In the absence of climaticchange, the results from a distributed water balancemodel applied in the humid south of the basinindicated a reduction in runoff by 1.3% in thescenario of maximum increase in forest areas below4,000 m.