Inverse analysis of fire-induced carbon emission from Equatorial Asia in 2015 with CONTRAIL and NIES-VOS data

<p>The fire-induced carbon emission in Equatorial Asia was estimated using the inverse system named NICAM-based Inverse Simulation for Monitoring (NISMON) carbon dioxide (CO<sub>2</sub>). The analysis was performed with the four-dimensional variational method for 2015, when the big El Niño was occurred. NISMON-CO<sub>2</sub> extensively used high-precision atmospheric mole fraction data of CO<sub>2</sub> from the commercial aircraft observation project of Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL). Furthermore, independent atmospheric CO<sub>2</sub> and carbon monoxide data from National Institute for Environmental Studies (NIES) Volunteer Observing Ship (VOS) Programme were used to elucidate the validity of the estimated fire-induced carbon emission. Finally, using both CONTRAIL and NIES-VOS CO<sub>2</sub> data, the inverse analysis indicated 273 Tg C for fire emission during September - October 2015. This two-month-long emission accounts for 75% of the annual total fire emission and 45% of the annual total net carbon flux within the region, indicating that fire emission is a dominant driving force of interannual variations of carbon fluxes in Equatorial Asia. In the future warmer climate condition, Equatorial Asia would experience more severe droughts and have risks for releasing a large amount of carbon into the atmosphere. Therefore, the continuation of these aircraft and shipboard observations is fruitful for reliable monitoring of carbon fluxes in Equatorial Asia.</p>

Analysis of Cloud Seeding Experiment by Aircraft: A Case Study of an International Joint Experiment in 2019

In this study, an international joint cloud seeding experiment (International Joint Cloud Observation and Weather Control Experiment 2019, IJCO-WCE 2019) by aircraft was analyzed using numerical simulations, ground observation data, and aircraft observation data. As a result of numerical simulations, it was found that the seeding material was diffused in a direction consistent with the wind direction observed by the aircraft. Further, aircraft observation data showed an increase in average water concentration of clouds and precipitation particles after seeding rather than during seeding. The average water concentration of clouds observed by the Cloud Droplet Probe (CDP) increased by about 59% after seeding than during seeding, and that observed by the Cloud Imaging Probe (CIP) increased by about 82%. In addition, precipitation particles observed by the Precipitation Imaging Probe (PIP) were hardly noticed during seeding, but appeared after seeding.

Commercial-Aircraft-Based Observations for NWP: Global Coverage, Data Impacts, and COVID-19

Weather observations from commercial aircraft constitute an essential component of the global observing system and have been shown to be the most valuable observation source for short-range numerical weather prediction (NWP) systems over North America. However, the distribution of aircraft observations is highly irregular in space and time. In this study, we summarize the recent state of aircraft observation coverage over the globe and provide an updated quantification of its impact upon short-range NWP forecast skill. Aircraft observation coverage is most dense over the contiguous United States and Europe, with secondary maxima in East Asia and Australia/New Zealand. As of late November 2019, 665 airports around the world had at least one daily ascent or descent profile observation; 400 of these come from North American or European airports. Flight reductions related to the COVID-19 pandemic have led to a 75% reduction in aircraft observations globally as of late April 2020. A set of data denial experiments with the latest version of the Rapid Refresh NWP system for recent winter and summer periods quantifies the statistically significant positive forecast impacts of assimilating aircraft observations. A special additional experiment excluding approximately 80% of aircraft observations reveals a reduction in forecast skill for both summer and winter amounting to 30%–60% of the degradation seen when all aircraft observations are excluded. These results represent an approximate quantification of the NWP impact of COVID-19-related commercial flight reductions, demonstrating that regional NWP guidance is degraded as a result of the decreased number of aircraft observations.

Onopvallend turen naar de Russen

Secretly watching the Russians. Cold War aircraft observation posts on existing buildings During the 1950s a network of aircraft observation post was built in The Netherlands, as a detection/observation system against low-flying hostile aircraft during the Cold War. Preferably, these were placed on highrise buildings. 134 of these 276 observation posts were built on existing buildings, on factories, mills, water towers, monasteries, government buildings and bunkers. Since their decommissioning in 1964-1968, many posts have been demolished. Approximately 37 posts on existing buildings remain, but mostly go unnoticed and many risk demolition in the future. These remaining aircraft observation posts are remarkable relics of our military heritage from the Cold War.

Biogenic isoprene emissions driven by regional weather predictions using different initialization methods: case studies during the SEAC⁴RS and DISCOVER-AQ airborne campaigns

Land and atmospheric initial conditions of the Weather Research and Forecasting (WRF) model are often interpolated from a different model output. We perform case studies during NASA's SEAC4RS and DISCOVER-AQ Houston airborne campaigns, demonstrating that using land initial conditions directly downscaled from a coarser resolution dataset led to significant positive biases in the coupled NASA-Unified WRF (NUWRF, version 7) surface and near-surface air temperature and planetary boundary layer height (PBLH) around the Missouri Ozarks and Houston, Texas, as well as poorly partitioned latent and sensible heat fluxes. Replacing land initial conditions with the output from a long-term offline Land Information System (LIS) simulation can effectively reduce the positive biases in NUWRF surface air temperature by ∼ 2 °C. We also show that the LIS land initialization can modify surface air temperature errors almost 10 times as effectively as applying a different atmospheric initialization method. The LIS-NUWRF-based isoprene emission calculations by the Model of Emissions of Gases and Aerosols from Nature (MEGAN, version 2.1) are at least 20 % lower than those computed using the coarser resolution data-initialized NUWRF run, and are closer to aircraft-observation-derived emissions. Higher resolution MEGAN calculations are prone to amplified discrepancies with aircraft-observation-derived emissions on small scales. This is possibly a result of some limitations of MEGAN's parameterization and uncertainty in its inputs on small scales, as well as the representation error and the neglect of horizontal transport in deriving emissions from aircraft data. This study emphasizes the importance of proper land initialization to the coupled atmospheric weather modeling and the follow-on emission modeling. We anticipate it to also be critical to accurately representing other processes included in air quality modeling and chemical data assimilation. Having more confidence in the weather inputs is also beneficial for determining and quantifying the other sources of uncertainties (e.g., parameterization, other input data) of the models that they drive.

Hypermanoeuvrability and visual cloaking: new adaptive aerostructures technologies for UAVs

The paper begins with a summary of the performance characteristics of the most important classes of adaptive aerostructures which are relevant for UAVs and the materials which drive them. The paper describes several classes of UAVs that take advantage of the various kinds of adaptive aerostructures technologies. These technologies are shown to be suitable for very small and even hard-launched UAVs, hovering, high speed, low speed and convertible UAVs (i.e. UAVs that can transition between helicopter and aircraft/missile flight modes). The first class of UAVs presented highlights newly invented post-buckled precompressed (PBP) actuators which are particularly well suited to enhancing convertible coleopters or ‘ultra-high performance UAVs.’ These UAVs are capable of hovering for extended periods of time as a helicopter in gusty, windy, dusty, real tactical environments, then popping up, converting and dashing out like a missile at several hundred knots. The paper shows photos (i.e. no computer simulations) of convertible coleopter launches from armoured vehicles, a battle-damage assessment exercise and a live fire sequence with 40mm munitions. The paper concludes with a description of the visual signature suppression (VSS) system which was employed on a 2m UAV. The VSS system was shown to suppress the visual cross section to below 1·8cm2 which is the threshold for human aircraft observation. Accordingly, VSS equipped aircraft are said to ‘disappear’ in mid flight.

Evaluation of Regional Aircraft Observations Using TAMDAR

A multiyear evaluation of a regional aircraft observation system [Tropospheric Aircraft Meteorological Data Reports (TAMDAR)] is presented. TAMDAR observation errors are compared with errors in traditional reports from commercial aircraft [aircraft meteorological data reports (AMDAR)], and the impacts of TAMDAR observations on forecasts from the Rapid Update Cycle (RUC) over a 3-yr period are evaluated. Because of the high vertical resolution of TAMDAR observations near the surface, a novel verification system has been developed and employed that compares RUC forecasts against raobs every 10 hPa; this revealed TAMDAR-related positive impacts on RUC forecasts—particularly for relative humidity forecasts—that were not evident when only raob mandatory levels were considered. In addition, multiple retrospective experiments were performed over two 10-day periods, one in winter and one in summer; these allowed for the assessment of the impacts of various data assimilation strategies and varying data resolutions. TAMDAR’s impacts on 3-h RUC forecasts of temperature, relative humidity, and wind are found to be positive and, for temperature and relative humidity, substantial in the region, altitude, and time range over which TAMDAR-equipped aircraft operated during the studied period of analysis.