Impact of Land Surface Initialization Approach on Subseasonal Forecast Skill: a Regional Analysis in the Southern Hemisphere

The authors use a sophisticated coupled land-atmosphere modeling system for a Southern Hemisphere subdomain centered over southeastern Australia to evaluate differences in simulation skill from two different land surface initialization approaches. The first approach uses equilibrated land surface states obtained from offline simulations of the land surface model, and the second uses land surface states obtained from reanalyses. The authors find that land surface initialization using prior offline simulations contribute to relative gains in subseasonal forecast skill. In particular, relative gains in forecast skill for temperature of 10%-20% within the first 30 days of the forecast can be attributed to the land surface initialization method using offline states. For precipitation there is no distinct preference for the land surface initialization method, with limited gains in forecast skill irrespective of the lead time. The authors evaluated the asymmetry between maximum and minimum temperatures and found that maximum temperatures had the largest gains in relative forecast skill, exceeding 20% in some regions. These results were statistically significant at the 98% confidence level at up to 60 days into the forecast period. For minimum temperature, using reanalyses to initialize the land surface contributed to relative gains in forecast skill, reaching 40% in parts of the domain that were statistically significant at the 98% confidence level. The contrasting impact of the land surface initialization method between maximum and minimum temperature was associated with different soil moisture coupling mechanisms. Therefore, land surface initialization from prior offline simulations does improve predictability for temperature, particularly maximum temperature, but with less obvious improvements for precipitation and minimum temperature over southeastern Australia

Atmospheric multiple scattering of fluorescence and Cherenkov light emitted by extensive air showers

Atmospheric scattering of light emitted by an air shower not only attenuates direct fluorescence light from the shower, but also contributes to the observed shower light. So far only direct and singly-scattered Cherenkov photons have been taken into account in routine analyses of the observed optical image of air showers. In this paper a Monte Carlo method of evaluating the contribution of multiply scattered light to the optical air shower image is presented, as well as results of simulations and a parameterization of scattered light contribution to measured shower signal.Comment: 27 pages, 18 figures, accepted for publication in NIM

Influence of Leaf Area Index Prescriptions on Simulations of Heat, Moisture, and Carbon Fluxes

Leaf-area index (LAI), the total one-sided surface area of leaf per ground surface area, is a key component of land surface models. We investigate the influence of differing, plausible LAI prescriptions on heat, moisture, and carbon fluxes simulated by the Community Atmosphere Biosphere Land Exchange (CABLEv1.4b) model over the Australian continent. A 15-member ensemble monthly LAI data-set is generated using the MODIS LAI product and gridded observations of temperature and precipitation. Offline simulations lasting 29 years (1980-2008) are carried out at 25 km resolution with the composite monthly means from the MODIS LAI product (control simulation) and compared with simulations using each of the 15-member ensemble monthly-varying LAI data-sets generated. The imposed changes in LAI did not strongly influence the sensible and latent fluxes but the carbon fluxes were more strongly affected. Croplands showed the largest sensitivity in gross primary production with differences ranging from -90 to 60 %. PFTs with high absolute LAI and low inter-annual variability, such as evergreen broadleaf trees, showed the least response to the different LAI prescriptions, whilst those with lower absolute LAI and higher inter-annual variability, such as croplands, were more sensitive. We show that reliance on a single LAI prescription may not accurately reflect the uncertainty in the simulation of the terrestrial carbon fluxes, especially for PFTs with high inter-annual variability. Our study highlights that the accurate representation of LAI in land surface models is key to the simulation of the terrestrial carbon cycle. Hence this will become critical in quantifying the uncertainty in future changes in primary production

Characteristics of geomagnetic cascading of ultra-high energy photons at the southern and northern sites of the Pierre Auger Observatory

Cosmic-ray photons above 10^19 eV can convert in the geomagnetic field and initiate a preshower, i.e. a particle cascade before entering the atmosphere. We compare the preshower characteristics at the southern and northern sites of the Pierre Auger Observatory. In addition to a shift of the preshower patterns on the sky due to the different pointing of the local magnetic field vectors, the fact that the northern Auger site is closer to the geomagnetic pole results in a different energy dependence of the preshower effect: photon conversion can start at smaller energies, but large conversion probabilitites (>90%) are reached for the whole sky at higher energies compared to the southern Auger site. We show how the complementary preshower features at the two sites can be used to search for ultra-high energy photons among cosmic rays. In particular, the different preshower characteristics at the northern Auger site may provide an elegant and unambiguous confirmation if a photon signal is detected at the southern site.Comment: 25 pages, 14 figures, minor changes, conclusions unchanged, Appendix A replaced, accepted by Astroparticle Physic

Gallium scintigraphy in the diagnosis and total lymphoid irradiation of Takayasu's arteritis

Takayasu's arteritis (TA) in children causes appreciable morbidity and mortality, predominantly as a result of the complication of renovascular hypertension (RVH). Ten children with TA, complicated by RVH, were treated at our centre over the past decade. An initial raised erythrocyte sedimentation rate (ESR) and a purified protein derivative greater than 15 mm were present in every case. More recently, gallium scintigraphy has been used to demonstrate sites of active inflammation in affected vessels (3/4 patients) which became negative after total lymphoid irradiation (TU). The latter was used in the last 6 children, and appeared to be effective in controlling disease activity as evinced in the normalisation of their ESRs and negative findings on gallium scintigraphy (in all 3 patients with prior active inflammation). Because of vascular damage caused by the vasculitic process, surgical intervention is often required to improve organ perfusion, particularly of the kidney/so Renal autografting (or allografting) seems preferable (6/11 kidneys functional) to renal bypass grafting (5/5 kidneys clotted). Patient survival improved when TU was used in addition to standard surgical and medical therapy; this included steroids and antituberculous therapy with TU, and steroids and cyclophosphamide in the two relapses. Five of 6 patients treated with TU were alive after 32 - 54 months' follow-up, while 4 patients who received standard medical and surgical therapy but not TU all died within 18 months of diagnosis. Gallium scintigraphy is a helpful diagnostic tool in assessing vasculitic activity in TA; TU is an important mode of immunosuppression, but still needs to be compared with cyclophosphamide as the major immunosuppressive

Design of DC Wirings for urban house in Indonesia including analysis on appliances, power losses, and costs: An alternative to Support Rooftop PV Uptake

Most of the application of solar PV in Indonesia uses inverter, which is a complex and expensive electronics system. Many of the PV plants are in fault condition due to the failure of the inverter. This paper proposed DC wirings powered by solar PV for houses in the urban area of Indonesia. First, the paper reviewed the availability of electrical appliances powered by DC voltage supply. Secondly, it presents AC and DC house wiring designs for a house with 1 300 VA electrical power limit. Losses of both wirings are analyzed and compared, including the cost of wirings materials. The survey showed appliances such as air conditioning, fridgefreezer, television, washing machine, and other appliances are now available in DC voltage supply. A 48 V DC bus is chosen to minimize losses. From a cost perspective, AC and DC wiring systems are comparable, but the DC house is slightly more expensive due to the cost of appliances. The cost of DC wirings is lower due to the lower cost of the DC-DC converters and uses fewer conductors. The results provide an alternative to using solar PV directly distributed as DC voltage for the houses in the urban area of the country

Subcontinental heat wave triggers terrestrial and marine, multi-taxa responses

Heat waves have profoundly impacted biota globally over the past decade, especially where their ecological impacts are rapid, diverse, and broad-scale. Although usually considered in isolation for either terrestrial or marine ecosystems, heat waves can straddle ecosystems of both types at subcontinental scales, potentially impacting larger areas and taxonomic breadth than previously envisioned. Using climatic and multi-species demographic data collected in Western Australia, we show that a massive heat wave event straddling terrestrial and maritime ecosystems triggered abrupt, synchronous, and multi-trophic ecological disruptions, including mortality, demographic shifts and altered species distributions. Tree die-off and coral bleaching occurred concurrently in response to the heat wave, and were accompanied by terrestrial plant mortality, seagrass and kelp loss, population crash of an endangered terrestrial bird species, plummeting breeding success in marine penguins, and outbreaks of terrestrial wood-boring insects. These multiple taxa and trophic-level impacts spanned \u3e300,000 km2—comparable to the size of California—encompassing one terrestrial Global Biodiversity Hotspot and two marine World Heritage Areas. The subcontinental multi-taxa context documented here reveals that terrestrial and marine biotic responses to heat waves do not occur in isolation, implying that the extent of ecological vulnerability to projected increases in heat waves is underestimated

Universal lateral distribution of energy deposit in air showers and its application to shower reconstruction

The light intensity distribution in a shower image and its implications to the primary energy reconstructed by the fluorescence technique are studied. Based on detailed CORSIKA energy deposit simulations, a universal analytical formula is derived for the lateral distribution of light in the shower image and a correction factor is obtained to account for the fraction of shower light falling into outlying pixels in the detector. The expected light profiles and the corresponding correction of the primary shower energy are illustrated for several typical event geometries. This correction of the shower energy can exceed 10%, depending on shower geometry.Comment: 21 pages, 9 figure