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DOE OSTI2024

The Extraordinary March 2022 East Antarctica “Heat” Wave. Part II: Impacts on the Antarctic Ice Sheet

Abstract Between 15 and 19 March 2022, East Antarctica experienced an exceptional heat wave with widespread 30°–40°C temperature anomalies across the ice sheet. In Part I, we assessed the meteorological drivers that generated an intense atmospheric river (AR) that caused these record-shattering temperature anomalies. Here, we continue our large collaborative study by analyzing the widespread and diverse impacts driven by the AR landfall. These impacts included widespread rain and surface melt that was recorded along coastal areas, but this was outweighed by widespread high snowfall accumulations resulting in a largely positive surface mass balance contribution to the East Antarctic region. An analysis of the surface energy budget indicated that widespread downward longwave radiation anomalies caused by large cloud-liquid water contents along with some scattered solar radiation produced intense surface warming. Isotope measurements of the moisture were highly elevated, likely imprinting a strong signal for past climate reconstructions. The AR event attenuated cosmic ray measurements at Concordia, something previously never observed. Last, an extratropical cyclone west of the AR landfall likely triggered the final collapse of the critically unstable Conger Ice Shelf while further reducing an already record low sea ice extent. Significance Statement Using our diverse collective expertise, we explored the impacts from the March 2022 heat wave and atmospheric river across East Antarctica. One key takeaway is that the Antarctic cryosphere is highly sensitive to meteorological extremes originating from the midlatitudes and subtropics. Despite the large positive temperature anomalies driven from strong downward longwave radiation, this event led to huge amounts of snowfall across the Antarctic interior desert. The isotopes in this snow of warm airmass origin will likely be detectable in future ice cores and potentially distort past climate reconstructions. Even measurements of space activity were affected. Also, the swells generated from this storm helped to trigger the final collapse of an already critically unstable Conger Ice Shelf while further degrading sea ice coverage.

Wille, Jonathan D.↗

NASA NTRS1988

Atmospheric Electrical Modeling in Support of the NASA F-106 Storm Hazards Project

A recently developed storm electrification model (SEM) is used to investigate the operating environment of the F-106 airplane during the NASA Storm Hazards Project. The model is 2-D, time dependent and uses a bulkwater microphysical parameterization scheme. Electric charges and fields are included, and the model is fully coupled dynamically, microphysically and electrically. One flight showed that a high electric field was developed at the aircraft's operating altitude (28 kft) and that a strong electric field would also be found below 20 kft; however, this low-altitude, high-field region was associated with the presence of small hail, posing a hazard to the aircraft. An operational procedure to increase the frequency of low-altitude lightning strikes was suggested. To further the understanding of lightning within the cloud environment, a parameterization of the lightning process was included in the SEM. It accounted for the initiation, propagation, termination, and charge redistribution associated with an intracloud discharge. Finally, a randomized lightning propagation scheme was developed, and the effects of cloud particles on the initiation of lightning investigated.

Helsdon, John H., Jr.↗

NASA NTRS2007

Self-consistent Model of Magnetospheric Electric Field, RC and EMIC Waves

Electromagnetic ion cyclotron (EMIC) waves are an important magnetospheric emission, which is excited near the magnetic equator with frequencies below the proton gyro-frequency. The source of bee energy for wave growth is provided by temperature anisotropy of ring current (RC) ions, which develops naturally during inward convection from the plasma sheet These waves strongly affect the dynamic s of resonant RC ions, thermal electrons and ions, and the outer radiation belt relativistic electrons, leading to non-adiabatic particle heating and/or pitch-angle scattering and loss to the atmosphere. The rate of ion and electron scattering/heating is strongly controlled by the Wave power spectral and spatial distributions, but unfortunately, the currently available observational information regarding EMIC wave power spectral density is poor. So combinations of reliable data and theoretical models should be utilized in order to obtain the power spectral density of EMIC waves over the entire magnetosphere throughout the different storm phases. In this study, we present the simulation results, which are based on two coupled RC models that our group has developed. The first model deals with the large-scale magnetosphere-ionosphere electrodynamic coupling, and provides a self-consistent description of RC ions/electrons and the magnetospheric electric field. The second model is based on a coupled system of two kinetic equations, one equation describes the RC ion dynamics and another equation describes the power spectral density evolution of EMIC waves, and self-consistently treats a micro-scale electrodynamic coupling of RC and EMIC waves. So far, these two models have been applied independently. However, the large-scale magnetosphere-ionosphere electrodynamics controls the convective patterns of both the RC ions and plasmasphere altering conditions for EMIC wave-particle interaction. In turn, the wave induced RC precipitation Changes the local field-aligned current distributions and the ionospheric conductances, which are crucial for a large-scale electrodynamics. The initial results from this new self-consistent model of the magnetospheric electric field, RC and EMIC waves will be shown in this presentation.

Gamayunov, K. V.↗

NASA NTRS2011

Weekly Cycle of Lightning and Associated Patterns of Rainfall, Cloud, and Aerosols over Korea and Adjacent Oceans during Boreal Summer

In this study, we analyze the weekly cycle of lightning over Korea and adjacent oceans and associated variations of aerosols, clouds, precipitation, and atmospheric circulations, using aerosol optical depth (AOD) from the NASA Moderate resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR), cloud properties from MODIS, precipitation and storm height from Tropical Rainfall Measuring Mission (TRMM) satellite, and lightning data from the Korean Lightning Detection Network (KLDN) during 9-year from 2002 to 2010. Lightning data was divided into three approximately equal areas, land area of Korea, and two adjacent oceans, Yellow Sea and South Sea. Preliminary results show that the number of lightning increases during the middle of the week over Yellow Sea. AOD data also shows moderately significant midweek increase at about the same time as lightning peaks. These results are consistent with the recent studies showing the invigoration of storms with more ice hydrometeors by aerosols, and subsequently wash out of aerosols by rainfall. Frequency of lightning strokes tend to peak at weekend in land area and over South Sea, indicating local weekly anomalous circulation between land and adjacent ocean. On the other hand, lightning frequency over Yellow Sea appears to have very strong weekly cycle with midweek peak on around Wednesday. It is speculated that the midweek peak of lightning over Yellow Sea was related with aerosol transport from adjacent land area. AOD data also suggests midweek peak over Yellow Sea, however, the weekly cycle of AOD was not statistically significant. Changes in weekly cycle of lightning from pre-monsoon to monsoon season, as well as associated clouds and circulation patterns are also discussed.

Kim, Ji-In↗

DOE OSTI2017

Examining the Hydrological Variations in an Aquaplanet World Using Wave Activity Transformation

Building on the recent advent of the concept of finite-amplitude wave activity, a contour-following diagnostics for column water vapor (CWV) is developed and applied to a pair of aquaplanet model simulations to understand and quantify the higher moments in the global hydrological cycle. The Lagrangian nature of the diagnostics leads to a more tractable formalism for the transient, zonally asymmetric component of the hydrological cycle, with a strong linear relation emerging between the wave activity and the wave component of precipitation minus evaporation ([Formula: see text]). The dry-versus-wet disparity in the transient hydrological cycle is measured by [Formula: see text], and it is found to increase at a super-Clausius–Clapeyron rate at the poleward side of the mean storm track in response to a uniform sea surface temperature (SST) warming and the meridional structure of the increase can be largely attributed to the change of the meridional stirring scale of the midlatitude Rossby waves. Further scaling for [Formula: see text] indicates that the rate of the wavy hydrological cycle, measured by the ratio of [Formula: see text] to the CWV wave activity, is subdued almost everywhere in the extratropics, implying an overall weakening of the transient circulation. Extending the CWV wave activity analysis to the transient moist regions helps reveal some unique characteristics of atmospheric rivers in terms of transport function, minimum precipitation efficiency, and maximum hydrological cycle rate, as well as an overall weakening of the hydrological cycle rate in the atmospheric river regions under SST warming.

Lu, Jian↗

DOE OSTI2026

The Effect of Large-scale Magnetic Fluctuations on Energetic Particle Profiles across Interplanetary Shocks

In situ observations of energetic particles associated with interplanetary (IP) shocks, known as energetic storm particle (ESP) events, often show time-intensity profiles quite different from predictions of classical diffusive shock acceleration theory. We use numerical simulations, including test-particle simulations and hybrid simulations (with fluid electrons and kinetic protons) for shocks propagating into a turbulent magnetic field to study the ESP intensity-time profiles across a strong IP shock. We find that several types of energetic particle intensity profiles similar to in situ observations can be produced in our simulations. The peak of energetic particle count is often near, but can be shifted from, the locations of the shock front, with the peak usually being observed downstream of the shock. These findings may help understand particle acceleration at both traveling IP shocks and shocks in other heliospheric and astrophysical environments.

Lo, Ming-Yuan [New Mexico Consortium (NMC), Los Al↗

NASA NTRS2002

The 1996-2002 Plunge in the North-Atlantic Oscillation Index Produces Cold Spring Temperatures in Central Europe

Surface-air temperatures in winter and spring in central Europe rose over the second half of the 20th century, reported for different data-spans, and by different approaches (Ross et al., 1996; Angell, 1999; Hansen et al., 1999; Demaree et al., 2002). Analysis with a finer temporal resolution shows that late-winter and early-spring (February and March) trends are much stronger than the 3-month season averages (Otterman et al., 2002a). Responding to this need for finer than 3- month resolution, observations at meteorological stations in central Europe are analyzed here for the years 1951-2002, computing six-pentad (5-day period) averages (effectively monthly averages for January, February, and March). The daily minimum surface-air temperature, T(sub min), and the daily maximum temperature, T(sub max), rose steeply in Berlin and Poznan' in the years 1951-1995. Based on sensitivity studies, the bulk of this sharp warming is due to stronger southwesterlies over the North Atlantic, with which the temperatures in Europe are strongly correlated (Otterman et al., 1999; 2002a). However, for the most recent seven years, a pronounced downturn of the warming is observed, which we attribute to the concurrent, 1996-2002, sharp downturn of the ocean-surface southwesterlies over the North Atlantic (Otterman et al., 2002b). Such changes in the ocean winds and variations in the storm tracks are associated with changes in the North Atlantic Oscillation, NAO (Rogers, 1997). The NAO index, the difference in the surface pressure between Iceland and Azores, constitutes a measure of the zonal winds over the eastern North Atlantic, and thus is a critically important factor influencing the flow of maritime air into Europe (but the temperature of the advected airmasses depends on the meridional component, as we discuss). The recent (1996-2002) downturn in this index resulted in much colder spring temperatures in Europe, with adverse significance for the growing season.

Atlas, Robert↗

NASA NTRS2013

Observations of C-Band Brightness Temperatures and Ocean Surface Wind Speed and Rain Rate from the Hurricane Imaging Radiometer (HIRAD) during GRIP and HS3

HIRAD is a new technology developed by NASA/MSFC, in partnership with NOAA and the Universities of Central Florida, Michigan, and Alabama-Huntsville. HIRAD is designed to measure wind speed and rain rate over a wide swath in heavy-rain, strong-wind conditions. HIRAD is expected to eventually fly routinely on unmanned aerial vehicles (UAVs) such as Global Hawk over hurricanes threatening the U.S. coast and other Atlantic basin areas, and possibly in the Western Pacific as well. HIRAD first flew on GRIP in 2010 and is part of the 2012-14 NASA Hurricane and Severe Storm Sentinel (HS3) mission on the Global Hawk, a high-altitude UAV. The next-generation HIRAD will include wind direction observations, and the technology can eventually be used on a satellite platform to extend the dynamical range of Ocean Surface Wind (OSV) observations from space.

Miller, Timothy L.↗

DOE OSTI2023

Interactions Between Lightning and Ship Traffic

It is important to understand connections between society and the natural environment for anticipating hazards and anthropogenic effects on the Earth system. In this study, we conduct a detailed exploration of interactions between oceanic thunderstorms and maritime traffic. Shipping traffic produces aerosols that perturb the otherwise “clean” ocean environment. Prior work proposed these aerosol effects as the cause of increased lightning over certain shipping lanes. However, introducing tall grounded objects into a high electric field environment might also facilitate lightning discharges, as we see with upward lightning over land. We consider both possibilities. Our analyses of the thunderstorms responsible for enhanced lightning activity over the shipping lane with the clearest anthropogenic signal indicate that the enhancement results from an increased frequency of lightning-producing storms. Observed variations in thunderstorm microphysics between the shipping lane and nearby oceans are small compared to natural factors such as the Indian monsoon, and are on the same scale as the local variability in the data. By contrast, matching lightning stroke data with ship transponder events in oceanic regions where public data are available reveals a strong signal from direct ship interactions. Lightning is 15× (66×) more likely to occur at a ship location compared to 2 km (25 km) away. These results highlight the central role of direct ship interactions in explaining lightning enhancements over shipping lanes. We also document the frequency of these direct lightning interactions across various categories of vessels and on individual ships present in the public data.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1991

An investigation of the detection of tornadic thunderstorms by observing storm top features using geosynchronous satellite imagery

The number of tornado outbreak cases studied in detail was increased from the original 8. Detailed ground and aerial studies were carried out of two outbreak cases of considerable importance. It was demonstrated that multiple regression was able to predict the tornadic potential of a given thunderstorm cell by its cirrus anvil plume characteristics. It was also shown that the plume outflow intensity and the deviation of the plume alignment from storm relative winds at anvil altitude could account for the variance in tornadic potential for a given cell ranging from 0.37 to 0.82 for linear to values near 0.9 for quadratic regression. Several predictors were used in various discriminant analysis models and in censored regression models to obtain forecasts of whether a cell is tornadic and how strong tornadic it could be potentially. The experiments were performed with the synoptic scale vertical shear in the horizontal wind and with synoptic scale surface vorticity in the proximity of the cell.

Anderson, Charles E.↗

NASA NTRS1999

Tropical Cyclone Paka's Initial Explosive Development (10-12 December, 1997)

Convection associated with an equatorial westerly wind burst was first observed late November during the strong El Nino of 1997 at approximately 2000 km southwest of the Hawaiian Islands. This region of convection lead to the formation of twin tropical cyclones, one in the southern hemisphere named Pam and the other in the northern hemisphere named Paka. During the first week in December, tropical cyclone Paka, the system of concern, reached tropical storm stage as it moved rapidly westward at relatively low latitudes. During the 10-12 of December, Paka rapidly developed into a typhoon.

Rodgers, Edward B.↗

NASA NTRS1995

Cloud Ozone Dust Imager (CODI): Investigation and Technical Plan - Volume 1

The Cloud Ozone Dust Imager (CODI) is proposed to investigate the current climatic balance of the Mars atmosphere, with particular emphasis on the important but poorly understood roles which dust and water ice aerosols play in this balance. The large atmospheric heating (20-50 K) resulting from global dust storms around Mars perihelion is well recognized. However, groundbased observations of Mars atmospheric temperatures, water vapor, and clouds since the Viking missions have identified a much colder, cloudier atmosphere around Mars aphelion that may prove as important as global dust storms in determining the interannual and long-term behavior of the Mars climate. The key climate issues CODI is designed to investigate are: 1) the degree to which non-linear interactions between atmospheric dust heating, water vapor saturation, and cloud nucleation influence the seasonal and interannual variability of the Mars atmosphere, and 2) whether the strong orbital forcing of atmospheric dust loading, temperatures and water vapor saturation determines the long-term balance of Mars water, as reflected in the north-south hemispheric asymmetries of atmospheric water vapor and polar water ice abundances. The CODI experiment will measure the daily, seasonal and (potentially) interannual variability of atmospheric dust and cloud opacities, and the key physical properties of these aerosols which determine their role in the climate cycles of Mars. CODI is a small (1.2 kg), fixed pointing camera, in which four wide-angle (+/- 70 deg) lenses illuminate fixed filters and CCD arrays. Simultaneous sky/surface imaging of Mars is obtained at an angular resolution of 0.28 deg/pixel for wavelengths of 255, 336, 502, and 673 nm (similar to Hubble Space Telescope filters). These wavelengths serve to measure atmospheric ozone (255 and 336 nm), discriminate ice and dust aerosols (336 and 673 nm), and construct color images (336, 502, and 673 nm). The CODI images are detected on four 512 x 512 pixel arrays, as partitioned on two 1024 x 1024 CCD's operated in frame transfer mode. The center of the CODI field-of-view is canted 40 deg from the zenith direction to obtain sky brightness measurements and a 20 deg surface field-of-view. Daily image observations will be conducted when the Sun is greater than or equal to 5 deg outside the edge of the CODI field-of-view, and twilight and nighttime imaging will obtained on a weekly basis. The 673 nm channel includes a polarizer wheel to obtain sky/surface polarimetry. A dust cover protects the entire lens assemblies of all four CODI channels. This opaque dust cover, which is normally opened for CODI imaging, includes a small fixed mirror and transparent window positioned above the 673 nm lens, to redirect the 673 nm field-of-view to the surface for descent imaging. Fixed pointing, internal data buffering, low operating power (2-4 W for less than or equal to 30 seconds), selective data transmission, and simple operational characteristics of the CODI experiment place minimum resource and operational demands on the Mars Surveyor 1998 lander. The CODI science goals are optimized for, but not restricted to, a low-latitude landing site (20 deg S-30 deg N). The primary CODI measurement objectives are the opacities, wave forms, particle properties (size, shape, and alignment), and heights of clouds; the opacities, particle properties, and vertical distribution of dust; and the opacity and vertical distribution of ozone. The variability of cloud, ozone, and dust opacities will be determined on diurnal, daily, and seasonal timescales. Wind velocities will be determined from cloud motions and wave characteristics; and the temporal variability of atmospheric water vapor, with limited altitude information, will be inferred from the CODI ozone observations. Secondary measurement objectives include limited descent imaging capability, surface uv-visible photometry and polarimetry, photochemistry, and meteorite infall rates.

Clancy, R. Todd↗

NASA NTRS2009

Multifluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms-Initial Results

The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered

Glocer, A.↗

DOE OSTI2026

Quasi‐Steady State Supersaturation: Do High Values Derived From ESCAPE Represent Real High Supersaturations and the Potential for Condensational Invigoration?

Deep convective clouds were intensively sampled during the Experiment of Sea Breeze Convection, Aerosols, Precipitation, and Environment (ESCAPE) with coordinated flights of the NRC Convair-580 and SPEC Learjet. A total of 219 updraft core segments were sampled over coastal Texas and Louisiana under diverse meteorological conditions. Median updraft properties included widths of ∼1 km, velocities of 4.8 m s −1 , droplet number concentrations of ∼400 cm −3 , and liquid water contents of 0.9 g m −3 . The limitations of using the quasi-steady state approximation to derive supersaturations were explored. Supersaturation (S QSS ) estimated from in situ observations under a quasi-steady state assumption averaged 0.4% but occasionally exceeded 2%, with values >1% (high supersaturations) identified as statistical outliers. Two case studies illustrated the conditions linked to high supersaturations. In a storm over the Gulf, median core S QSS reached 2.46% in the developing stage compared to 2.17% in the mature stage under similar thermodynamic conditions. In a storm over coastal Louisiana, S QSS peaked near 11% within a 13.7-m s −1 updraft, accompanied by predominantly supercooled liquid droplets at −13°C and exceptionally low diameter concentrations of 0.29 mm cm −3 . Bootstrap analysis of all sampled cores showed that high supersaturations are most probable in cold and mixed-phase regimes with moderate to strong updrafts and are strongly influenced by vertical velocity and droplet number concentrations. In conclusion, while extreme supersaturations (∼10%) were rare, their occurrence underscores the need for targeted multiplatform observations to resolve their spatiotemporal variability and assess their potential role in deep convective invigoration.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2023

Climate Impacts of Convective Cloud Microphysics in NCAR CAM5

Here we improved the treatments of convective cloud microphysics in the NCAR Community Atmosphere Model version 5.3 (CAM5.3) by 1) implementing new terminal velocity parameterizations for convective ice and snow particles, 2) adding graupel microphysics, 3) considering convective snow detrainment, and 4) enhancing rain initiation and generation rate in warm clouds. Furthermore, we evaluated the impacts of improved microphysics on simulated global climate, focusing on simulated cloud radiative forcing, graupel microphysics, convective cloud ice amount, and tropical precipitation. Compared to CAM5.3 with the default convective microphysics, the too-strong cloud shortwave radiative forcing due primarily to excessive convective cloud liquid is largely alleviated over the tropics and midlatitudes after rain initiation and generation rate is enhanced, in better agreement with the CERES-EBAF estimates. Geographic distributions of graupel occurrence are reasonably simulated over continents; whereas the graupel occurrence remains highly uncertain over the oceanic storm-track regions. When evaluated against the CloudSat–CALIPSO estimates, the overestimation of convective ice mass is alleviated with the improved convective ice microphysics, among which adding graupel microphysics and the accompanying increase in hydrometeor fall speed play the most important role. The probability distribution function (PDF) of rainfall intensity is sensitive to warm rain processes in convective clouds, and enhancement in warm rain production shifts the PDF toward heavier precipitation, which agrees better with the TRMM observations. Common biases of overestimating the light rain frequency and underestimating the heavy rain frequency in GCMs are mitigated.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1991

The sun and interplanetary magnetic field

The interplanetary magnetic field (IMF) serves as a link between the sun, the response of the earth to solar activity and variations in galactic cosmic radiation. The IMF originates as a solar-coronal magnetic field that is transported into space by the solar wind. The close connection between solar magnetic fields and the origin and structure of the solar wind is described. The solar wind forms the heliosphere, a cavity containing the magnetized solar plasma from which the interstellar plasma and field are excluded. The entry of galactic cosmic rays into the heliosphere and their strong interaction with the IMF are discussed, this topic being of primary importance to the production and temporal variations of radiogenic elements. The profound influence of the IMF on geomagnetic activity and the aurora is discussed within the context of merging or reconnection with the planetary field. The physical connection is thus established between solar magnetic fields, magnetic storms and aurora. The state of the solar wind and IMF during the Maunder minimum is considered and an explanation for the (relative) absence of sunspots and aurora is proposed. The mechanism is an interruption of the oscillatory solar dynamo, a consequent reduction in the heating of the corona, a cessation of the supersonic solar wind and a weakening or absence of southward-directed magnetic fields in the vicinity of the earth.

Smith, Edward J.↗

NASA NTRS1997

A Model Study of Zonal Forcing in the Equatorial Stratosphere by Convectively Induced Gravity Waves

A two-dimensional cloud-resolving model is used to examine the possible role of gravity waves generated by a simulated tropical squall line in forcing the quasi-biennial oscillation (QBO) of the zonal winds in the equatorial stratosphere. A simulation with constant background stratospheric winds is compared to simulations with background winds characteristic of the westerly and easterly QBO phases, respectively. In all three cases a broad spectrum of both eastward and westward propagating gravity waves is excited. In the constant background wind case the vertical momentum flux is nearly constant with height in the stratosphere, after correction for waves leaving the model domain. In the easterly and westerly shear cases, however, westward and eastward propagating waves, respectively, are strongly damped as they approach their critical levels, owing to the strongly scale-dependent vertical diffusion in the model. The profiles of zonal forcing induced by this wave damping are similar to profiles given by critical level absorption, but displaced slightly downward. The magnitude of the zonal forcing is of order 5 m/s/day. It is estimated that if 2% of the area of the Tropics were occupied by storms of similar magnitude, mesoscale gravity waves could provide nearly 1/4 of the zonal forcing required for the QBO.

Alexander, M. J.↗

NASA NTRS2006

Time Relevance of Convective Weather Forecast for Air Traffic Automation

The Federal Aviation Administration (FAA) is handling nearly 120,000 flights a day through its Air Traffic Management (ATM) system and air traffic congestion is expected to increse substantially over the next 20 years. Weather-induced impacts to throughput and efficiency are the leading cause of flight delays accounting for 70% of all delays with convective weather accounting for 60% of all weather related delays. To support the Next Generation Air Traffic System goal of operating at 3X current capacity in the NAS, ATC decision support tools are being developed to create advisories to assist controllers in all weather constraints. Initial development of these decision support tools did not integrate information regarding weather constraints such as thunderstorms and relied on an additional system to provide that information. Future Decision Support Tools should move towards an integrated system where weather constraints are factored into the advisory of a Decision Support Tool (DST). Several groups such at NASA-Ames, Lincoln Laboratories, and MITRE are integrating convective weather data with DSTs. A survey of current convective weather forecast and observation data show they span a wide range of temporal and spatial resolutions. Short range convective observations can be obtained every 5 mins with longer range forecasts out to several days updated every 6 hrs. Today, the short range forecasts of less than 2 hours have a temporal resolution of 5 mins. Beyond 2 hours, forecasts have much lower temporal. resolution of typically 1 hour. Spatial resolutions vary from 1km for short range to 40km for longer range forecasts. Improving the accuracy of long range convective forecasts is a major challenge. A report published by the National Research Council states improvements for convective forecasts for the 2 to 6 hour time frame will only be achieved for a limited set of convective phenomena in the next 5 to 10 years. Improved longer range forecasts will be probabilistic as opposed to the deterministic shorter range forecasts. Despite the known low level of confidence with respect to long range convective forecasts, these data are still useful to a DST routing algorithm. It is better to develop an aircraft route using the best information available than no information. The temporally coarse long range forecast data needs to be interpolated to be useful to a DST. A DST uses aircraft trajectory predictions that need to be evaluated for impacts by convective storms. Each time-step of a trajectory prediction n&s to be checked against weather data. For the case of coarse temporal data, there needs to be a method fill in weather data where there is none. Simply using the coarse weather data without any interpolation can result in DST routes that are impacted by regions of strong convection. Increasing the temporal resolution of these data can be achieved but result in a large dataset that may prove to be an operational challenge in transmission and loading by a DST. Currently, it takes about 7mins retrieve a 7mb RUC2 forecast file from NOAA at NASA-Ames Research Center. A prototype NCWF6 1 hour forecast is about 3mb in size. A Six hour NCWFG forecast with a 1hr forecast time-step will be about l8mb (6 x 3mb). A 6 hour NCWF6 forecast with a l5min forecast time-step will be about 7mb (24 x 3mb). Based on the time it takes to retrieve a 7mb RUC2 forecast, it will take approximately 70mins to retrieve a 6 hour NCWF forecast with 15min time steps. Until those issues are addressed, there is a need to develop an algorithm that interpolates between these temporally coarse long range forecasts. This paper describes a method of how to use low temporal resolution probabilistic weather forecasts in a DST. The beginning of this paper is a description of some convective weather forecast and observation products followed by an example of how weather data are used by a DST. The subsequent sections will describe probabilistic forecasts followed by a descrtion of a method to use low temporal resolution probabilistic weather forecasts by providing a relevance value to these data outside of their valid times.

Chan, William N.↗