The Impacts Of Airborne Cloud Microphysical Instrumentation Mounting Location On Measurements Made During The Observations Of Aerosols And Clouds And Their Interactions (ORACLES) Project

ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) was a five-year NASA investigation into the climate impacts of Southern Africa’s biomass burning aerosols. The University of North Dakota, in coordination with the Cooperative Institute for Severe and High-Impact Weather Research and Operations, the University of Oklahoma and University of Illinois at Urbana-Champaign integrated and operated a suite of in-situ cloud microphysical instrumentation into the NASA P-3 Orion aircraft to study aerosol-cloud interactions within this region. However, during the course of the individual ORACLES campaigns, the accuracy of the cloud microphysical observations were uncertain due to the mounting location of instruments with respect to the aircraft wing. To address these concerns, an additional wing-mounted pylon design was created and was installed moving the instruments ahead of the leading edge of the aircraft wing in order to sample freestream conditions for ORACLES-2017 and ORACLES-2018. To study the impact of mounting location on cloud microphysical observations taken during ORACLES, a computational fluid dynamical analysis of the NASA P-3 Orion with both pylon designs is performed. Utilizing the OpenFOAM software package, a Eulerian-Lagrangian framework is utilized to simulate compressible flow with particle tracking around the aircraft, mounting locations, and instrumentation. Simulations of the predominant ORACLES vertical cloud sampling profiles, known as sawtooths, and multiple environmental factors are considered. Within the simulated Cloud Droplet Probe sample volume, the departure of the velocity field from freestream conditions was found to vary by up to twelve percent during sawtooth maneuvers for the NASA P-3 original pylon design. While the new pylon design did not achieve freestream conditions, it did minimize this distortion in flow caused by the sawtooth maneuvers, with a five percent difference in the departure of the velocity field from freestream between ascent and descent sawtooth profiles. Overall, the original NASA P-3 pylon design observed the closest velocities to freestream conditions across all simulations

Sensitivity Of Two-Dimensional Stereo (2DS) Probe Derived Parameters To Particle Orientation

Information on the size distribution, orientation and the axial ratio of ice particles is important for the improvement of precipitation retrievals by polarized radar. However, uncertainty in the natural particle orientation and axial ratios remains due to the difficulty in obtaining in situ observations of these parameters. This difficulty arises because of possible re-orientation of particles by airflow around aircraft sampling instrumentation. Due to this possible re-orientation, observations of ice particles become a function of the viewing angle of the sampling instrumentation. The two-dimensional stereo (2D-S) optical array probe (OAP) manufactured by SPEC, Inc. offers the capability for comparison between two orthogonal sample volumes (vertical and horizontal) and the determination of whether previously unknown errors in particle image aspect ratio, size distribution and other derived parameters arise due to the viewing angle of imaging instruments. To further understand the effect of particle orientation on OAP measurements, microphysical data collected with the University of North Dakota Citation II research aircraft during the Integrated Precipitation and Hydrology Experiment (IPHEx) and Olympic Mountain Experiment (OLYMPEx) are analyzed. Planar and columnar type ice crystals have been previously shown to fall with their broad face horizontal. However, 2D-S measurements of aspect ratios indicate a preferred vertical orientation of these particles within the sample volume of the instrument. Analysis of the effects of this orientation suggest that planar crystals are under-represented, and under sized, within OAP measurements

ERK2 alone drives inflammatory pain but cooperates with ERK1 in sensory neuron survival

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are highly homologous yet distinct components of signal transduction pathways known to regulate cell survival and function. Recent evidence indicates an isoform-specific role for ERK2 in pain processing and peripheral sensitization. However, the function of ERK2 in primary sensory neurons has not been directly tested. To dissect the isoform-specific function of ERK2 in sensory neurons, we used mice with Cre-loxP-mediated deletion of ERK2 in Na(v)1.8(+) sensory neurons that are predominantly nociceptors. We find that ERK2, unlike ERK1, is required for peripheral sensitization and cold sensation. We also demonstrate that ERK2, but not ERK1, is required to preserve epidermal innervation in a subset of peptidergic neurons. Additionally, deletion of both ERK isoforms in Na(v)1.8(+) sensory neurons leads to neuron loss not observed with deletion of either isoform alone, demonstrating functional redundancy in the maintenance of sensory neuron survival. Thus, ERK1 and ERK2 exhibit both functionally distinct and redundant roles in sensory neurons. SIGNIFICANCE STATEMENT ERK1/2 signaling affects sensory neuron function and survival. However, it was not clear whether ERK isoform-specific roles exist in these processes postnatally. Previous work from our laboratory suggested either functional redundancy of ERK isoforms or a predominant role for ERK2 in pain; however, the tools to discriminate between these possibilities were not available at the time. In the present study, we use new genetic knock-out lines to demonstrate that ERK2 in sensory neurons is necessary for development of inflammatory pain and for postnatal maintenance of peptidergic epidermal innervation. Interestingly, postnatal loss of both ERK isoforms leads to a profound loss of sensory neurons. Therefore, ERK1 and ERK2 display both functionally distinct and redundant roles in sensory neurons

Fuel lifecycle and long term fire behavior responses to fuel treatments in southeastern US pine ecosystems

We completed an investigation of the long term legacies of fuels treatments in longleaf pine sandhills at Eglin Air Force Base in the panhandle of Florida. From 1994-1999, The Nature Conservancy conducted a large-scale, long-term study at Eglin Air Force Base to compare the effectiveness of midstory reduction treatments, including herbicide, growing season fire, and mechanical clearing on the restoration of longleaf sandhill pine forests. The study plots have been monitored continuously since the completion of the original study and information still exists for all experimental sites, which have been burned as part of the prescribed fire program at Eglin AFB since the study concluded. We examined the legacy of these treatments on fire behavior 15+ years later in these plots. We measured multiple aspects of fuels and fire behavior in a subset of the original plots using a combination spatially explicit fuel sampling, high resolution visual and thermal imagery, wide and narrow field of view radiometers, thermocouples and thermopiles to collect data on fuel type, fuel loading, radiant and convective heat fluxes. We collected data in nine large operational prescribed fires that included the treatment plots in 2011. Preliminary data analyses showed that the impact of the treatments was not detectable in our measurements. The occurrence of frequent low intensity fires in the treatments appeared to have driven a convergence of fuel characteristics in plots with and without management interventions in as little as 16 years. Within stand variation in overstory derived fuels appeared to be more important in explaining fire behavior than the original treatments. We also completed an investigation of heat transfer in midstory oak stems. While these results are still being analyzed we found that in species with rough bark, heat transfer is much more complex and necessitates the consideration of three-dimensional information on bark topography and surface heating to develop accurate tissue damage models. The data we have collected will allow us to make those improvements. We also have developed a promising means (photogrammetry coupled with IR imagery) to rapidly capture the fine scale surface topography and heating of stems useful for improving such models

Influence of Repeated Canopy Scorching on Soil CO\u3csub\u3e2\u3c/sub\u3e Efflux

Forest ecosystems experience various disturbances that can affect belowground carbon cycling to different degrees. Here, we investigate if successive annual foliar scorching events will result in a large and rapid decline in soil CO2 efflux, similar to that observed in girdling studies. Using the fire-adapted longleaf pine (Pinus palustris Mill.) tree species, we experimentally manipulated foliar leaf area and thus, canopy photosynthesis, via foliar scorching over two consecutive growing seasons. We monitored the effect of scorching on soil CO2 efflux and fine root production, mortality, standing crop, and nitrogen (N) and non-structural carbohydrate (i.e. sugar and starch) concentrations. Despite an immediate 80% reduction in foliar leaf area and sap flow rates from the scorch treatment, there was no effect on soil CO2 efflux in either year. Likewise, the cumulative soil CO2 flux after two scorch treatments remained comparable to that of the control treatment, even after assuming a 100% decline in the autotrophic component for the month following the two scorching events. Fine root standing crop was not diminished by scorching because both fine root production and mortality increased commensurately in the scorch treatment. Fine root N and sugar concentrations were not diminished by scorching, but starch concentrations of 5th order roots decreased after the second scorching treatment, presumably because starch was mobilized from larger roots to maintain more metabolically active 1st order roots. The lack of response observed in soil CO2 efflux following successive canopy scorches differs from the response often observed after girdling and suggests that the carbohydrate reserves of longleaf pine trees are sufficient to maintain root metabolism for extended periods even after an extreme canopy perturbation. We propose that tree species in ecosystems that experience frequent disturbance may allocate more carbon to storage than those in less disturbed ecosystems, and as a result are more resilient to disturbances that affect photosynthate supply. Such species should be capable of maintaining belowground autotrophic respiration during periods of minimal or nonexistent carbon assimilation