A highly elliptical orbit space system for hydrometeorological monitoring of the Arctic region by V. V. Asmus1, V. N. Dyadyuchenko2, Y. I. Nosenko3, G. M. Polishchuk4 and V. A. Selin3 The lack of reliable, frequently high latitudes. It has therefore been • Monitoring of climate change updated information on the Earth’s suggested that demonstration of polar ice caps is a signifi cant problem a hydrometeorological system of • Data collection and relay for weather forecasting, affecting satellites on highly elliptical orbit from land-, sea- and air-based forecast skill for the entire planet. The (HEO), called the “Arctica” system, observing platforms poor numerical weather prediction should be created to provide the (NWP) skill for the Arctic region necessary complex information for the • Exchange and dissemination of and the Earth’s northern territories diffi cult tasks involved in developing processed hydrometeorological is caused primarily by errors in the whole Arctic region. and heliogeophysical data. determining initial conditions, which depend on the quality of initial Signifi cantly, the hydrometeorological Further progress in global and data. Until now, initial data have observations carried out in the regional numerical weather prediction been received from meteorological Arctic within the framework of the depends to a large extent on: geostationary satellites, which are International Polar Year 2007-2008 not very effective in scanning high are not provided with remote-sensing • Quasi-continuous reception latitudes and polar-orbiting satellites data received simultaneously and of hydrometeorological and with inadequate refresh rates. It is quasi-continuously throughout the heliogeophysical satellite data on therefore vital to ensure regular Arctic region. the Arctic region and the Earth’s reception of integrated satellite northern territories; information on the Arctic region in To develop the Arctic region as a order to address the most pressing whole, improvement is needed in • Reception of data from high- hydrometeorological, geophysical, the following: latitude drifting buoys, geochemical, ecological and disaster- automatic weather stations related tasks in this area. • Analysis and forecasting of: and emergency buoys of the – Weather at regional (Arctic) Cospas-Sarsat air-and-sea Of course, the methods used to and global levels search-and-rescue system, via analyse hydrometeorological fi elds in – Ice cover in the Arctic satellite communication channels modern numerical weather prediction Ocean in 24-hour, uninterrupted systems are universal and their – Heliogeophysical conditions teleaccess mode; accuracy should not depend on one in the near-Earth space particular region. However, acquiring – Flight conditions for avia- • Operational delivery of short- highly accurate initial conditions tion (cloudiness, wind, jet range weather forecasts and ice (particularly wind vectors) would streams, etc.) cover data to users via satellite be possible only with additional communication channels. effective observations made at • Monitoring of disasters Over the past few years, the intensifi cation of weather and climate 1 Scientifi c Research Centre on Space Hydrometeorology “Planeta” anomalies has made the task of 2 Russian Federal Service for Hydrometeorology and Environmental Monitoring increasing the reliability of medium- (Roshydromet) 3 Federal Space Agency (ROSCOMOS) and long-range weather forecasts 4 S.A. Lavochkin Scientifi c Production Association even more crucial. WMO Bulletin 56 (4) - October 2007 | 293 As of 2002, initial data from the The effectiveness of the long-term covering territories at latitudes higher basic geostationary satellites system of Arctic drifting buoys and than 60°N within the Earth‘s Arctic have been supplemented (at first the network of automatic weather region (polar cap) using instruments experimentally but later operationally) stations in northern countries will be similar to the modern imagers on by calculations of wind fi eld vectors largely determined by the possibilities basic meteorological geostationary in polar areas (latitudes higher than for effi cient data transfer from these satellites. 65°N) using Moderate Resolution platforms to regional and national Imaging Spectroradiometer (MODIS) hydrometeorological centres. Roscosmos and Roshydromet observations from the low-orbiting propose to create and introduce the Terra and Aqua Earth Observing The Arctic region presents Arctica highly elliptical orbit satellite System satellites (US National difficulties for observations using system to demonstrate monitoring Aeronautics and Space Administration the basic international meteorological hydrometeorological conditions in the (NASA)). geostationary satellites, the area of Arctic region and within the Earth’s quality monitoring on geostationary northern territories (at latitudes Experimental use of MODIS data, orbits being limited by the zenith higher than 60°N), using the current despite their local character, low angle of observation of 70°, which scientifi c and technological surface- updating frequency and other corresponds to 60° of latitude. The based infrastructure. disadvantages when compared with communication channels available on geostationary data, has resulted in geostationary satellites cannot ensure The design of the Arctica system a steady increase in the accuracy good-quality data reception from was outlined in the joint report by of numerical weather predictions. Arctic drifting buoys and automatic the Roscosmos and Roshydromet Moreover, a positive impact has been weather stations. delegations to the seventh session of noticed not only for high-latitude the WMO Consultative Meetings on regions, but also for extra-tropical Over the past few years, therefore, the High-level Policy on Satellite Matters parts of the whole forecast area. It has Meteorological Services and Space in January 2007 and Fifteenth World also been found that MODIS-derived Agencies of Canada, the European Meteorological Congress in May data on “polar” winds are most useful Union, the Russian Federation and 2007. in the event of “bad” forecasts. the USA have become increasingly interested in the development of satel- As recorded in the minutes of the fi rst This research was carried out at the lite hydrometeorological systems meeting of the WMO International Goddard Space Flight Center (GSFC) on highly elliptical orbits (peri- Working Group to establish possible and NASA’s Jet Propulsion Laboratory gee ≈1 000 km; apogee ≈40 000 km; international cooperation on the and the results have been reported inclination ≈ 63°; orbital period Arctica project, held in April 2007, at international conferences on ≈12 hours). it was recommended that this satellite meteorology and meetings project be discussed further within of the International Working Group Highly elliptical orbits with an apogee the framework of the international on Satellite Methods of Wind Vector of ≈40 000 km and an orbital period of GEOLAB project. Evaluation. 12 hours are preferred because they permit the use of scanner-imagers The advantages of highly elliptical Two factors making reliable wind from geostationary satellites with orbits over geostationary orbits for vector evaluations using MODIS data slight improvements and have a Arctic observations are shown in from low-orbiting satellites more fairly long useful lifetime (≈7 years), Figure 1. diffi cult to obtain are: owing to more favourable radiation conditions. These orbits have been The Arctica system’s functionalities • Significant time lapse (up given the name “Molniya”*-type would complement those of exist- to 100 minutes) between orbits because of their priority and ing international geostationary observations on two consecutive considerable experience of the Russian meteo ro logical satellites, whose passes (it takes about 2.5 hours Federation in launching satellites of data, according to WMO, form the to receive a triplet of images, the same name on these orbits. basis for continuous global Earth as opposed to 0.5 hours with observations in the 21st century. geostationary satellites); The main aim of putting these Its main function is the operational systems on highly elliptical orbits reception of hydrometeorological • Need for highly accurate is to have quasi-continuous satellite information (wind speed and direction, geographical referencing hydrometeorological data (particularly cloud parameters, precipitation, procedures and “correction” of on the so-called “polar” wind vectors) ice cover, etc.) in the Arctic region images, in other words: bringing as input to weather analysis and the images into nominal form. * Molniya means: lightning forecasting. In addition, the system 294 | WMO Bulletin 56 (4) - October 2007 with the exception of the Antarctic, although even this task could be End of the operational covered by increasing the number part of HEO Beginning of the operational part of HEO of HEO satellites to four and selecting appropriate orbits. 70° limiting angle of qualitative observation The Arctica space system consists of two satellites on HEOs, a ground- Area for qualitative monitoring from HEO based complex for the reception, processing and distribution of Area for qualitative GEO monitoring satellite data with data reception points and a surface-based satellite control complex. The Arctica system’s surface-based resources consist of a series of centres distributed across the area for the reception, Figure 1 — Advantages of highly elliptical orbits over geostationary orbits