Committee On Space Research Research Articles

Semi-empirical thermosphere model evaluation at low altitude with GOCE densities

Aims : The quality of the Committee on Space Research (COSPAR) International Reference Atmosphere models NRLMSISE-00, JB2008, and DTM2013 in the 150–300 km altitude range has never been thoroughly evaluated due to a lack of good density data. This study aims at providing the model accuracies thanks to the recent high-resolution high-accuracy Gravity field and steady-state Ocean Circulation Explorer (GOCE) density dataset. The evaluation was performed on yearly, monthly, and daily time scales, which are important for different applications such as mission design, mission operation, or re-entry predictions. Methods : The accuracy of the models was evaluated by comparing to the GOCE density observations of the Science Mission (1 November 2009–20 October 2013) and new density data at the lowest altitudes derived for the last weeks before the re-entry (22 October–8 November 2013) according to a metric, which consists of computing mean, standard deviation and root mean square (RMS) of the observed-to-model ratios, and correlation. Mean statistics are then calculated over the three time scales. Results : The range of model biases, standard deviations, and correlations becomes larger when the time interval decreases, and this study provides COSPAR International Reference Atmosphere (CIRA) model statistics in the altitude range of 275–170 km. DTM2013 is the least biased and most accurate model on all time scales, essentially thanks to the database, notably containing two years of GOCE densities, to which it was fitted. NRLMSISE-00 performs worst, with considerable bias of about 20% in 2009 and 2013, and systematically higher standard deviations (lower correlations) than JB2008 and DTM2013. The performance of JB2008 is presently only slightly behind DTM2013, thanks to the new release 4_2g solar activity proxies. However, it still presents some weakness under the lowest solar activity conditions in 2009 and 2010. Comparison to Challenging Mini-Satellite Payload (CHAMP) density data showed that the results based on GOCE densities, despite limited local solar time coverage of 6–8 am & pm, are representative of model performance.

The International Reference Ionosphere: Rawer's IRI and its status today

Abstract. When the Committee on Space Research (COSPAR) initiated the International Reference Ionosphere (IRI) project in 1968 it wisely selected K. Rawer as its first Chairperson. With a solid footing and good contacts in both the ground-based and space-based ionospheric communities he was ideally suited to pull together colleagues and data from both communities to help build the first version of the IRI. He assembled a team of 20+ international ionospheric experts in the IRI Working Group and chaired and directed the group from 1968 to 1984. The working group has now grown to 63 members and the IRI model has undergone many revisions as new data became available and new modeling techniques were applied. This paper was presented during a special session of the Kleinheubach Tagung 2013 in honor of K. Rawer's 100th birthday. It will review the current status of the IRI model and project and the international recognition it has achieved. It is quite fitting that this year we not only celebrate K. Rawer's 100th birthday but also the exciting news that his favorite science endeavor, IRI, has been internationally recognized as an ISO (International Standardization Organization) standard. The IRI homepage is at http://irimodel.org.

Activities of the COSPAR Panel on Exploration supporting the Global Exploration Roadmap

The Global Exploration Roadmap (GER) is driven by several goals and objectives that include space science, the search for life as well as preparatory science activities to enable human space exploration. The Committee on Space Research (COSPAR), through its Commissions and Panels provides an international forum that supports and promotes space exploration worldwide. COSPAR's Panel on Exploration (PEX) investigates a stepwise approach of preparatory research on Earth and in Low Earth Orbit (LEO) to facilitate a future global space exploration program. We summarize recent activities and workshops of PEX in support of the GER.

The International Reference Ionosphere 2012 – a model of international collaboration

The International Reference Ionosphere (IRI) project was established jointly by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) in the late sixties with the goal to develop an international standard for the specification of plasma parameters in the Earth’s ionosphere. COSPAR needed such a specification for the evaluation of environmental effects on spacecraft and experiments in space, and URSI for radiowave propagation studies and applications. At the request of COSPAR and URSI, IRI was developed as a data-based model to avoid the uncertainty of theory-based models which are only as good as the evolving theoretical understanding. Being based on most of the available and reliable observations of the ionospheric plasma from the ground and from space, IRI describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 km to 2000 km. A working group of about 50 international ionospheric experts is in charge of developing and improving the IRI model. Over time as new data became available and new modeling techniques emerged, steadily improved editions of the IRI model have been published. This paper gives a brief history of the IRI project and describes the latest version of the model, IRI-2012. It also briefly discusses efforts to develop a real-time IRI model. The IRI homepage is at http://IRImodel.org.

Reaching 1 m Deep on Mars: The Icebreaker Drill

The future exploration of Mars will require access to the subsurface, along with acquisition of samples for scientific analysis and ground-truthing of water ice and mineral reserves for in situ resource utilization. The Icebreaker drill is an integral part of the Icebreaker mission concept to search for life in ice-rich regions on Mars. Since the mission targets Mars Special Regions as defined by the Committee on Space Research (COSPAR), the drill has to meet the appropriate cleanliness standards as requested by NASA's Planetary Protection Office. In addition, the Icebreaker mission carries life-detection instruments; and in turn, the drill and sample delivery system have to meet stringent contamination requirements to prevent false positives. This paper reports on the development and testing of the Icebreaker drill, a 1 m class rotary-percussive drill and triple redundant sample delivery system. The drill acquires subsurface samples in short, approximately 10 cm bites, which makes the sampling system robust and prevents thawing and phase changes in the target materials. Autonomous drilling, sample acquisition, and sample transfer have been successfully demonstrated in Mars analog environments in the Arctic and the Antarctic Dry Valleys, as well as in a Mars environmental chamber. In all environments, the drill has been shown to perform at the "1-1-100-100" level; that is, it drilled to 1 m depth in approximately 1 hour with less than 100 N weight on bit and approximately 100 W of power. The drilled substrate varied and included pure ice, ice-rich regolith with and without rocks and with and without 2% perchlorate, and whole rocks. The drill is currently at a Technology Readiness Level (TRL) of 5. The next-generation Icebreaker drill weighs 10 kg, which is representative of the flightlike model at TRL 5/6.

The international reference ionosphere today and in the future

The international reference ionosphere (IRI) is the internationally recognized and recommended standard for the specification of plasma parameters in Earth’s ionosphere. It describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 to 1,500 km. A joint working group of the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) is in charge of developing and improving the IRI model. As requested by COSPAR and URSI, IRI is an empirical model being based on most of the available and reliable data sources for the ionospheric plasma. The paper describes the latest version of the model and reviews efforts towards future improvements, including the development of new global models for the F2 peak density and height, and a new approach to describe the electron density in the topside and plasmasphere. Our emphasis will be on the electron density because it is the IRI parameter most relevant to geodetic techniques and studies. Annual IRI meetings are the main venue for the discussion of IRI activities, future improvements, and additions to the model. A new special IRI task force activity is focusing on the development of a real-time IRI (RT-IRI) by combining data assimilation techniques with the IRI model. A first RT-IRI task force meeting was held in 2009 in Colorado Springs. We will review the outcome of this meeting and the plans for the future. The IRI homepage is at http://www.IRI.gsfc.nasa.gov.

Community Radiative Transfer Model for Stratospheric Sounding Unit

AbstractTo better use the Stratospheric Sounding Unit (SSU) data for reanalysis and climate studies, issues associated with the fast radiative transfer (RT) model for SSU have recently been revisited and the results have been implemented into the Community Radiative Transfer Model version 2. This study revealed that the spectral resolution for the sensor’s spectral response functions (SRFs) calculations is very important, especially for channel 3. A low spectral resolution SRF results, on average, in 0.6-K brightness temperature (BT) errors for that channel. The variations of the SRFs due to the CO2 cell pressure variations have been taken into account. The atmospheric transmittance coefficients of the fast RT model for the Television and Infrared Observation Satellite (TIROS)-N, NOAA-6, NOAA-7, NOAA-8, NOAA-9, NOAA-11, and NOAA-14 have been generated with CO2 and O3 as variable gases. It is shown that the BT difference between the fast RT model and line-by-line model is less than 0.1 K, but the fast RT model is at least two orders of magnitude faster. The SSU measurements agree well with the simulations that are based on the atmospheric profiles from the Earth Observing System Aura Microwave Limb Sounding product and the Sounding of the Atmosphere using Broadband Emission Radiometry on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. The impact of the CO2 cell pressures shift for SSU has been evaluated by using the Committee on Space Research (COSPAR) International Reference Atmosphere (CIRA) model profiles. It is shown that the impacts can be on an order of 1 K, especially for SSU NOAA-7 channel 2. There are large brightness temperature gaps between observation and model simulation using the available cell pressures for NOAA-7 channel 2 after June 1983. Linear fittings of this channel’s cell pressures based on previous cell leaking behaviors have been studied, and results show that the new cell pressures are reasonable. The improved SSU fast model can be applied for reanalysis of the observations. It can also be used to address two important corrections in deriving trends from SSU measurements: CO2 cell leaking correction and atmospheric CO2 concentration correction.

Report on the 37th COSPAR (Committee on Space Research) Scientific Assembly

Report on the 37th COSPAR (Committee on Space Research) Scientific Assembly

50 years of COSPAR celebrated at its 37th Scientific Assembly

This report presents some of the space policy-related highlights of the 37th Committee on Space Research (COSPAR) Scientific Assembly held in Montreal from 13 to 20 July 2008. As the assembly coincided with the 50th anniversary of the Committee and was on the trailing edge of the 50th anniversary of the International Geophysical Year, the report first provides some background on the formation and significance of COSPAR.

International Standards Will Enhance Space Weather Management

In the decade since the National Space Weather Program (NSWP) Implementation Plan (see http://www.nswp.gov/images/nswpip2000.pdf) was drafted and then published (2000), and the NSWP Assessment Committee produced its 2006 follow-on report (http://www.nswp.gov/nswp_acreport0706.pdf), an updated vision has been needed to guide our nation's space environment activities as the decade near solar maximum begins. This vision must include two parts: placing space weather management at the forefront of activities to go beyond the ongoing specification and prediction efforts, and working to create international space environment standards so that space activities are conducted with safety, efficiency, and the maximization of space commercialization.

The COSPAR Capacity-Building Workshop Programme, 2000–2007

AbstractThe Committee on Space Research (COSPAR) Capacity-Building Programme introduces astronomers in the developing world to the rich resource of space research online archives. The programme consists of a series of regional workshops which each bring together about 30 developing world astronomers with around 8 teaching faculty for lectures and hands-on projects. Five workshops have been held so far with another two planned for next year and a budget which enables on average one workshop each year. Proposals for future workshops are encouraged.

Hubert Curien

Hubert Curien

35 years of International Reference Ionosphere – Karl Rawer’s legacy

Abstract. This presentation is given in honor of Prof. Karl Rawer’s 90th birthday. It looks back at 35 years of research and development in the framework of the International Reference Ionosphere (IRI) project. K. Rawer initiated this international modeling effort and was the first Chairman of the IRI Working Group. IRI is a joint project of the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) whose goal it is to establish an international standard model for the ionospheric densities, temperatures and drifts. This year we are celebrating Karl Rawer’s 90th birthday and also the 35-year anniversary of the IRI effort. My talk will review the close involvement of Karl Rawer in all stages of the development and improvement of this international standard from early on and his still very active participation in this effort.

Karl Rawer's life and the history of IRI

This laudation is given in honor of the 90th birthday of Prof. Karl Rawer that coincides with the 35th anniversary of the International Reference Ionosphere (IRI). The ionosphere was discovered during Karl Rawer's life, and he has dedicated his life to the exploration of this part of Earth's environment. The horrible events of world wars I and II shaped his early life, but they also launched his career as one of the eminent geophysical scientists of the twentieth century. The paper looks back at Karl's life and the 35 years of research and development in the framework of the IRI project. K. Rawer initiated this international modeling effort and was the first chairman of the IRI Working Group. IRI is a joint project of the Committee on Space Research (COSPAR) and the International Union of Radio science (URSI) that has the goal to establish an international standard model of the ionospheric densities temperatures, and drifts.

Seeking nominations for COSPAR awards and medals

The Committee on Space Research (COSPAR) is seeking candidates to be nominated for COSPAR awards and medals.

The Seasonal Variation of the Propagating Diurnal Tide in the Mesosphere and Lower Thermosphere. Part II: The Role of Tidal Heating and Zonal Mean Winds

A linear mechanistic tidal model is used to understand the mechanisms responsible for the seasonal variation of the propagating diurnal tide in the mesosphere and lower thermosphere simulated in the Canadian Middle Atmosphere Model (CMAM). The linear model uses a spectral approach to represent the horizontal structure of the tidal perturbations and employs dissipative processes that do not depend on season. By constraining the model with the zonal mean zonal winds, zonal mean temperatures, and tidal heating from the CMAM, the relative role of each of these terms is assessed. The linear model is able to reproduce all of the important tidal features found in the CMAM, in particular the semiannual amplitude variation in the lower thermosphere at low latitudes that is seen in observations. From this analysis the effects of both heating and mean winds are found to be responsible for the seasonal variation of the tidal amplitude, while variations in the tidal phase are attributed solely to changes in the mean winds. The strong sensitivity of the tide to the mean winds is the novel result of this study. This sensitivity is attributed to latitudinal shears in the zonal mean easterlies in the summer mesosphere. Although these shears occur on an annual basis, their impact on tidal amplitudes in the lower thermosphere is semiannual as a result of the 6-month shift in seasons between the two hemispheres. Simulations using observational datasets from the Committee on Space Research (COSPAR) International Reference Atmosphere (CIRA) and the High Resolution Doppler Imager (HRDI) reveal significant differences in the resulting tidal structure from that obtained using the CMAM winds, and point to possible deficiencies in these datasets.

International Reference Ionosphere 2000

The International Reference Ionosphere (IRI) is the international standard for the specification of ionospheric densities and temperatures. It was developed and is being improved‐updated by a joint working group of the International Union of Radio Science (URSI) and the Committee on Space Research (COSPAR). A new version of IRI is scheduled for release in the year 2000. This paper describes the most important changes compared to the current version of IRI: (1) an improved representation of the electron density in the region from the F peak down to the E peak including a better description of the F1 layer occurrence statistics and a more realistic description of the low‐latitude bottomside thickness, (2) inclusion of a model for storm‐time conditions, (3) inclusion of an ion drift model, (4) two new options for the electron density in the D region, and (5) an improved model for the topside electron temperatures. The outcome of the most recent IRI Workshops (Kühlungsborn, 1997, and Nagoya, 1998) will be reviewed, and the status of several ongoing task force activities (e.g., efforts to improve the representation of electron and ion densities in the topside ionosphere and the inclusion of a plasmaspheric extension) will be discussed. A few typical IRI applications will be highlighted in section 6.

Reply: Report safeguards future studies of Europa

I am able to reply to some of the issues raised in the comment above.Since the National Research Council Task Group on the Forward Contamination of Europa has officially disbanded, I cannot address the issues concerning the soundness or completeness of our report, or the proposal by Greenberg and Tufts for an alternate guiding principle for planetary protection. The National Academy of Sciences, NASA, and the International Council of Scientific Unions' Committee on Space Research (COSPAR) have received the Task Group report and may wish to address these concerns.

The importance of EUV indices for the international reference ionosphere

The International Reference Ionosphere (IRI), a standard model for ionospheric densities and temperatures developed by a joint working group of the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI), is widely used for specifications of the ionospheric environment. This paper will discuss the importance of the solar and/or ionospheric indices for driving the IRI model. The different existing indices will be reviewed and future needs will be outlined.

Relations with international organizations

The various relations of the IAF with international organizations are recalled, in particular those with the United Nations Committee on the Peaceful Uses of Outer space (COPUOS) and with the Committee on Space Research (COSPAR).