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Maintaining the Continuity of the Global Climate Data Record of Lightning from Space

Lightning is a natural hazard, an indicator of changes in convective storm behavior across multiple spatial and temporal scales, and a major influence on climate-affecting chemicals such as ozone and methane. Lightning also has substantial impacts on the near-space environment. As such, the World Meteorological Organization (WMO) has designated lightning as an Essential Climate Variable (ECV); that is, a measurement that is really important for understanding Earth’s climate. Spaceborne lightning observations are the gold standard for measuring global lightning, as the detection efficiency is more spatially uniform compared to ground-based lightning measurements. In addition, spaceborne is the only practical method for measuring total lightning (i.e., both intracloud and cloud-to-ground) at the global scale, as ground-based networks have limited ability to detect intracloud lightning at long distances (e.g., over oceans, far from land-based sensors). Since 1995, with only a two-year gap (2015-2017), lightning has been observed globally using a combination of Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) instruments. However, the year 2023 is the planned end for the International Space Station (ISS) LIS mission, and there is no designated low-Earth orbit (LEO) successor yet identified. Since 2017, geostationary (GEO) observations of lightning have become increasingly available. These include the U.S. Geostationary Lightning Mappers (GLMs), China’s Lightning Mapping Imager (LMI), and Europe’s Lightning Imager (LI). While GEO provides continuous, quasi-hemispheric coverage of lightning and thunderstorms, there are current gaps preventing global coverage, particularly in portions of Asia and the western Pacific, as well as high-latitude regions. Moreover, integration of the GEO constellation into a Climate Data Record (CDR) of lightning is a major challenge only recently begun to be addressed by the WMO. Furthermore, recent work has demonstrated some deficiencies in the global record of lightning from space. For example, small lightning flashes are very common in severe weather, but are difficult to observe using the present set of spaceborne lightning imagers. Moreover, some types of lightning are best observed using frequencies other than the commonly used near-infrared (777-nm), including ultraviolet and the radio spectrum. Finally, it is not possible to assess the vertical distribution of lightning globally, even though this measurement is highly relevant to thunderstorm behavior as well as lightning’s effects on greenhouse gases and the near-space environment. This presentation will provide a current assessment of lightning measurements from space, will identify significant current and future gaps in these observations, and will evaluate potential solutions for improving the overall CDR of global lightning.

Timothy Lang↗

NASA NTRS2024

Celebrating 10 Years of the Sub-Seasonal to Seasonal Prediction Project and Looking to the Future

The conference clearly demonstrated the increasing interest and growth of the scientific community working on the development and application of sub-seasonal to seasonal prediction since the start of the World Weather Research Programme (WWRP)/World Climate Research Programme (WCRP) sub-seasonal to seasonal (S2S) prediction project in 2013. The conference, which was held at the University of Reading (United Kingdom), was organized into three main themes as briefly summarized below, with eleven invited talks, 74 oral contributed talks, and 101 posters. The conference also included a two-hour breakout session, wherein eight groups discussed the current state and prospect for S2S prediction, and an early career researcher event. A summary of these discussions and recommendations is presented below. The conference web page (https://research.reading.ac.uk/s2s-summit2023/) is archived at the University of Reading. Introductory comments by representatives of the World Meteorological Organization (WMO) WWRP and WCRP emphasized the importance of the weather–climate linkage, targeted by S2S forecasts (from 2 weeks to a season ahead), addressing the challenges of creating “end-to-end” forecasts that encompass the entire climate-services chain from the prediction science and forecast, to the development and issuing of forecast products tailored to informing user-decisions. They also emphasized the efficacy of multi-model ensemble efforts and databases to foster collaborations internationally and between operational centres and academia. Although the WWRP/WCRP S2S project comes to an end in 2023, S2S prediction will remain an important focus for WWRP and WCRP. In WWRP, a new project called SAGE (Sub-seasonal to seasonal predictions for Agriculture and Environment) will start in 2024. Another important legacy of the S2S project will be the maintenance of the S2S database (Vitart et al. 2017) and the establishment of a WMO Lead Center for sub-seasonal prediction multi-model ensemble (LC-SSPMME) which will provide real-time multi-model S2S climate information. In two keynote presentations, Prof. Brian Hoskins (University of Reading) and Dr. Gilbert Brunet (Australian Bureau of Meteorology) discussed the potential of S2S predictability and the ongoing journey for understanding and improving these predictions. This conference was a sequel to the International Conference on Sub-seasonal to Seasonal Prediction (Robertson et al., 2014) which took place in College Park (Maryland, USA) in February 2014 to celebrate the start of the WWRP/WCRP S2S project, and to WCRP and WWRP conferences in Boulder, USA, in 2018 (Merryfield et al., 2020). A significant development compared to the previous S2S conferences was the large number of presentations on research to operation (R2O) and S2S applications and on the use of artificial intelligence and machine learning (AI/ML) methods for S2S prediction. Some of these methods provide empirical S2S forecasts which are competitive with state-of-the-art dynamical models. Other presentations demonstrated that AI/ML can provide alternative calibration of dynamical model outputs to traditional methods. Several talks and posters highlighted the increasing use of AI/ML, including deep learning, in S2S forecast post-processing and using AI to identify higher flow-dependent skill. Finally, some presentations demonstrated the value of AI/ML methods for a better understanding of S2S sources of predictability and attribution of extreme events.

S. J. Woolnough↗

NASA NTRS2017

Coupled Data Assimilation for Integrated Earth System Analysis and Prediction: Goals, Challenges, and Recommendations

The purpose of this report is to identify fundamental issues for coupled data assimilation (CDA), such as gaps in science and limitations in forecasting systems, in order to provide guidance to the World Meteorological Organization (WMO) on how to facilitate more rapid progress internationally. Coupled Earth system modeling provides the opportunity to extend skillful atmospheric forecasts beyond the traditional two-week barrier by extracting skill from low-frequency state components such as the land, ocean, and sea ice. More generally, coupled models are needed to support seamless prediction systems that span timescales from weather, subseasonal to seasonal (S2S), multiyear, and decadal. Therefore, initialization methods are needed for coupled Earth system models, either applied to each individual component (called Weakly Coupled Data Assimilation - WCDA) or applied the coupled Earth system model as a whole (called Strongly Coupled Data Assimilation - SCDA). Using CDA, in which model forecasts and potentially the state estimation are performed jointly, each model domain benefits from observations in other domains either directly using error covariance information known at the time of the analysis (SCDA), or indirectly through flux interactions at the model boundaries (WCDA). Because the non-atmospheric domains are generally under-observed compared to the atmosphere, CDA provides a significant advantage over single-domain analyses. Next, we provide a synopsis of goals, challenges, and recommendations to advance CDA: Goals: (a) Extend predictive skill beyond the current capability of NWP (e.g. as demonstrated by improving forecast skill scores), (b) produce physically consistent initial conditions for coupled numerical prediction systems and reanalyses (including consistent fluxes at the domain interfaces), (c) make best use of existing observations by allowing observations from each domain to influence and improve the full earth system analysis, (d) develop a robust observation-based identification and understanding of mechanisms that determine the variability of weather and climate, (e) identify critical weaknesses in coupled models and the earth observing system, (f) generate full-field estimates of unobserved or sparsely observed variables, (g) improve the estimation of the external forcings causing changes to climate, (h) transition successes from idealized CDA experiments to real-world applications. Challenges: (a) Modeling at the interfaces between interacting components of coupled Earth system models may be inadequate for estimating uncertainty or error covariances between domains, (b) current data assimilation methods may be insufficient to simultaneously analyze domains containing multiple spatiotemporal scales of interest, (c) there is no standardization of observation data or their delivery systems across domains, (d) the size and complexity of many large-scale coupled Earth system models makes it is difficult to accurately represent uncertainty due to model parameters and coupling parameters, (e) model errors lead to local biases that can transfer between the different Earth system components and lead to coupled model biases and long-term model drift, (e) information propagation across model components with different spatiotemporal scales is extremely complicated, and must be improved in current coupled modeling frameworks, (h) there is insufficient knowledge on how to represent evolving errors in non-atmospheric model components (e.g. as sea ice, land and ocean) on the timescales of NWP.

CDA↗

NASA NTRS2018

Some General and Fundamental Requirements for Designing Observing System Simulation Experiments (OSSEs)

The intent of this white paper is to inform WMO projects and working groups, together with the broader weather research and general meteorology and oceanography communities, regarding the use of Observing System Simulation Experiments (OSSEs). This paper is not intended to be either a critical or cursory review of past OSSE efforts. Instead, it describes some fundamental, but often neglected, aspects of OSSEs and prescribes important caveats regarding their design, validation, and application. Well designed, properly validated, and carefully conducted OSSEs can be invaluable for examining, understanding, and estimating impacts of proposed observing systems and new data assimilation techniques. Although significant imperfections and limitations should be expected, OSSEs either profoundly complement or uniquely provide both qualitative and quantitative characterizations of potential analysis of components of the earth system.

WMO↗

NASA NTRS1979

Lightning as an indication of storm severity

There is a substantial case for the theory that cloud electrification is related primarily to strong convection and the sizeable relative air motion that it implies; therefore, the electrification and subsequent discharge rates can be related to the air motion environment of thunderstorms. The isoceraunic contour map used by the WMO for observing and measuring thunderstorm occurrence contains no information on flash rates, flash density, flash relationship to storm severity, or flash variation with meteorological environment. A constant-view geosynchronous lightning mapper would permit simultaneous studies of the lightning discharge patterns and the meteorological environment of storms, thus establishing whether or not there is a reliable enough relationship to use the observed flash rates and characteristics as supplemental guidance for storm forecast refinement.

Dodge, J. C.↗

NASA NTRS1982

The International Ozone Intercomparison Program

The World Meteorological Organization (WMO) has endorsed a number of intercomparison project activities in recent years as a part of its Global Ozone Research and Monitoring Project. The present investigation is concerned with an intercomparison of rocket borne measurement techniques in continuation of that overall effort. The objectives of this investigation were to compare the performance of rocket borne instruments, via a set of simultaneous intercomparisons of various rocket instruments under at least two sets of conditions. In order to accomplish the objectives and to aid in validating the historical data, six daytime sensors from each participant were flown. In addition, two of the participants (Australia and U.S.) provided nighttime sensor measurements. Attention is given to Wallops Flight Center instrumentation and launch support, the Triad Series, The Morning Series, and the Nighttime Series.

Gurkin, L. W.↗

NASA NTRS1984

The photochemical time constants of minor constituents and their families in the middle atmosphere

A comprehensive formula is worked out for the photochemical time constant of minor constituents in the middle atmosphere. The formula is particularly useful for evaluating the time constants for families of some chemical species that are strongly coupled by rapid exchange reactions. Height profiles of photochemical time constants are calculated for individual species and their families based on the chemical reaction rate constants recommended in the recent WMO and JPL reports. Potential exchange reactions among various family members are discussed, and the effects of the choice of family membership on the time constant are evaluated.

Shimazaki, T.↗

NASA NTRS1982

PMP-1: A coordinated study of the behavior of the middle atmosphere in winter

The following observations of the middle atmosphere were available regularly: radiosonde data distributed through arrangements made by the World Meteorological Organization (WMO); radiosonde data; and the infrared radiances of the SSU (stratospheric sounding unit onboard the operational NOAA satellites). Other data of more experimental nature which are or will become available are, data from the Nimbus-7 satellite, especially from the Stratosphere and Mesospheric Sounder (SAMS) and the Limb Infrared Monitor of the Stratosphere (LIMS), but only for the winter of 1978 to 1979. These data are collected and integrated into the large-scale meteorological field analysis. Parameters necessary for the understanding of the large-scale dynamics of the middle atmosphere are derived.

Labitzke, K.↗

NASA NTRS1985

Climatology of the equatorial lower stratosphere

Twenty years of radiosonde data have been analyzed in an attempt to develop a latitudinal structure climatology of winds, temperature and geopotential at 30 and 50 mb in the equatorial stratosphere. The fine latitudinal resolution provided by the WMO station network reveals several interesting features in the latitudinal structure of the annual and quasi-biennial cycles which dominate this region. For example, the westerly and easterly acceleration phases of the quasi-biennial oscillation are markedly different. Westerly accelerations appear first at the equator, spreading outward with time to higher latitudes, and are more intense, on average, than the easterly accelerations. The easterly accelerations are more uniform in latitude, but less uniform in time, sometimes occurring in two stages. The quasi-biennial wind and temperature oscillations are symmetric about the equator, while the annual harmonic in zonal wind is antisymmetric about the equator, but is not proportional to the Coriolis parameters. Monthly mean zonal wind and temperature appear to be in thermal wind balance at the equator. Some brief remarks are also made concerning variability of the quasi-biennial oscillation and the effects of El Chichon.

Dunkerton, T. J.↗

NASA NTRS1985

Seasonal and diurnal variation of the atmospheric NO2 at Syowa Station, Antarctica

Extensive attention has been directed to nitrogen dioxide (NO2) since its important role in the atmospheric chemistry relating to the stratospheric ozone (e.g., WMO, 1982) has been pointed out. However, the behavior of NO2 in the atmosphere has still not been fully confirmed, although ground-based, balloon and satellite measurements of NO2 have been reported by many scientists. Especially, only a few measurements made at high latitude in the Southern Hemisphere have been reported. The total atmospheric NO2 by ground-based visible absorption spectroscopy at Syowa Station (69 deg S, 39.6 deg E), Antarctica. The observation continued from March 1983, to January 1984. The principles of measurement, instrumentation and the method of data analysis are described in detail.

Shibasaki, K.↗

NASA NTRS1985

Hydrogen species

Measurements of the members of the HO(x) family (OH, HO2, and H2O2) and their major source gases, H2O, and CH4 are discussed. Emphasis is placed on measurements which were made since the 1982 World Meteorologic Organization (WMO) report. Measurement techniques, available data, an assessment of data reliability, and a comparison of the data with theoretical distributions of stratospheric HO(x) species predicted from one and two dimensional photochemical models are discussed.

Schiff, H. I.↗

NASA NTRS1986

Preliminary estimates of radiosonde thermistor errors

It has been long realized that radiosonde temperature measurements are subject to errors, not the least of which is the effect of long- and short-wave radiation. Methods of adjusting the daytime temperatures to a nighttime equivalent temperature were developed a number of years ago, and are used by some analysis centers. Other than providing consistent observations for analysis this procedure does not provide a true correction. The literature discusses the problem of radiosonde temperature errors but it is not apparent what effort, if any, has been taken to quantify these errors. In order to quantify this radiation error, radiosondes containing multiple thermistors with different coatings were flown at Goddard Space Flight Center/Wallops Flight Facility. The coatings employed had different spectral characteristics and, therefore, different absorption and emissivity properties. Discrimination of the recorded temperatures enabled day and night correction values to be determined for the US standard white-coated rod thermistor. The correction magnitudes are given and a comparison of US measured temperatures before and after correction are compared with temperatures measured with the Vaisala radiosonde. The US and Vaisala radiosonde data are from the recently completed WMO International Radiosonde Intercomparison held at Wallops. The corrections are in the proper direction, day and night, and reduce day-night temperature differences to less than 0,5°C between surface and 30 hPa. The present uncorrected temperatures used with the Viz radiosonde have day-night differences that exceed 1°C at levels below 90 hPa. Additional measurements are planned to confirm these preliminary results and determine the solar elevation angle effect on the corrections. The technique used to obtain the corrections may also be used to recover a true 'absolute' value and might be considered a valuable contribution to the meteorological community for use as a reference instrument.

Temperature measurement↗

NASA NTRS1992

Comparisons of observed ozone and temperature trends in the lower stratosphere

One result of the ozone assessment (WMO, 1989) is that there is a significant negative ozone trend in the lower stratosphere and upper troposphere from 1970 through 1986. The relationship of this trend in ozone to that of temperature in the same altitude region is examined utilizing a 62-station set of rawinsonde data, and the results are compared to the changes in temperature determined from a radiative equilibrium model calculation. The calculated and observed trends in lower stratospheric temperature indicate substantial agreement in the shape and magnitude of the vertical profiles.

Miller, A. J.↗

NASA NTRS1991

Heterogeneous processes: Laboratory, field, and modeling studies

The efficiencies of chemical families such as ClO(x) and NO(x) for altering the total abundance and distribution of stratospheric ozone are controlled by a partitioning between reactive (active) and nonreactive (reservoir) compounds within each family. Gas phase thermodynamics, photochemistry, and kinetics would dictate, for example, that only about 1 percent of the chlorine resident in the lower stratosphere would be in the form of active Cl or ClO, the remainder existing in the reservoir compounds HCl and ClONO2. The consistency of this picture was recently challenged by the recognition that important chemical transformations take place on polar regions: the Airborne Antarctic Ozone Experiment (AAOE) and the Airborne Arctic Stratospheric Expedition (AASA). Following the discovery of the Antarctic ozone hole, Solomon et al. suggested that the heterogeneous chemical reaction: ClONO2(g)+HCl(s) yields Cl2(g)+HNO3(s) could play a key role in converting chlorine from inactive forms into a species (Cl2) that would rapidly dissociate in sunlight to liberate atomic chlorine and initiate ozone depletion. The symbols (s) and (g) denote solid phase, or adsorbed onto a solid surface, and gas phase, respectively, and represent the approach by which such a reaction is modeled rather than the microscopic details of the reaction. The reaction was expected to be most important at altitudes where PSC's were most prevalent (10 to 25 km), thereby extending the altitude range over which chlorine compounds can efficiently destroy ozone from the 35 to 45 km region (where concentrations of active chlorine are usually highest) to lower altitudes where the ozone concentration is at its peak. This chapter will briefly review the current state of knowledge of heterogeneous processes in the stratosphere, emphasizing those results obtained since the World Meteorological Organization (WMO) conference. Sections are included on laboratory investigations of heterogeneous reactions, the characteristics and climatology of PSC's, stratospheric sulfate aerosols, and evidence of heterogeneous chemical processing.

Poole, Lamont R.↗

NASA NTRS1991

Ultraviolet radiation changes

A major consequence of ozone depletion is an increase in solar ultraviolet (UV) radiation received at the Earth's surface. This chapter discusses advances that were made since the previous assessment (World Meteorological Organization (WMO)) to our understanding of UV radiation. The impacts of these changes in UV on the biosphere are not included, because they are discussed in the effects assessment.

Mckenzie, Richard L.↗

NASA NTRS1992

Global Temperature and Salinity Pilot Project

Data exchange and data management programs have been evolving over many years. Within the international community there are two main programs to support the exchange, management and processing of real time and delayed mode data. The Intergovernmental Oceanographic Commission (IOC) operate the International Oceanographic Data and Information Exchange (IODE) program which coordinates the exchange of delayed mode data between national oceanographic data centers, World Data Centers and the user community. The Integrated Global Ocean Services System is a joint IOC/World Meteorological Organization (WMO) program for the exchange and management of real-time data. These two programs are complemented by mechanisms that have been established within scientific programs to exchange and manage project data sets. In particular TOGA and WOCE have identified a data management requirement and established the appropriate infrastructure to achieve this. Where GTSPP fits into this existing framework is discussed.

Searle, Ben↗

NASA NTRS1985

Use of wind data in global modelling

The European Centre for Medium Range Weather Forecasts (ECMWF) is producing operational global analyses every 6 hours and operational global forecasts every day from the 12Z analysis. How the wind data are used in the ECMWF golbal analysis is described. For each current wind observing system, its ability to provide initial conditions for the forecast model is discussed as well as its weaknesses. An assessment of the impact of each individual system on the quality of the analysis and the forecast is given each time it is possible. Sometimes the deficiencies which are pointed out are related not only to the observing system itself but also to the optimum interpolation (OI) analysis scheme; then some improvements are generally possible through ad hoc modifications of the analysis scheme and especially tunings of the structure functions. Examples are given. The future observing network over the North Atlantic is examined. Several countries, coordinated by WMO, are working to set up an 'Operational WWW System Evaluation' (OWSE), in order to evaluate the operational aspects of the deployment of new systems (ASDAR, ASAP). Most of the new systems are expected to be deployed before January 1987, and in order to make the best use of the available resources during the deployment phase, some network studies are carried out at the present time, by using simulated data for ASDAR and ASAP systems. They are summarized.

Pailleux, J.↗

NASA NTRS1994

Observational and modeling studies of heat, moisture, precipitation and global-scale circulation patterns

This research grant was a revised version of an original proposal. The period of the grant was for three years with a six-month no-cost extension; thus, it was from 20 July 1990 to 19 January 1994. The objectives of the grant were to identify periods and locations of active convection centers, primarily over the Southern Hemisphere tropical Indian and Pacific Oceans; determine reasons for any periodic behavior found in the first objective; identify cases where subtropical jets over the South Pacific persisted for several days and examine the influences of tropical versus extra-tropical mechanisms in maintaining them; obtain estimates of precipitation by Q(sub 1) and Q(sub 2) budgets, including the importance of terms in each of the respective budgets, and compare these estimates to those obtained by other methods; and diagnose the distributions of moisture and precipitable water over the North Atlantic Ocean using routine analyses and satellite microwave data. To accomplish these objectives, we used grant funds to purchase several data sets, including the Global Precipitation Climate Project (GPCP) observations of station precipitation, ECMWF WCRP/TOGA archive two analyses for January 1985 - December 1990, ECMWF WMO analyses for January 1980 - December 1987, and OLR data for July 1974 - December 1991. We already had some SSM/I data and GLA analyses from a previous grant. In addition, to improve our computing power, we also used grant funds to purchase an IBM PS/2 with accessories, a NEC laser jet printer, and a microcomputer system for word processing. This report is organized as follows. Our research team is listed first. Section two contains a summary of our significant accomplishments; however, a detailed discussion of research results is not included since this information can be found in the accompanying reprints and preprints. Section three offers some concluding remarks, and a complete bibliographic summary is given in Section four.

Vincent, Dayton G.↗