HANDBOOK Use of radio spectrum for meteorology: weather, climate, water and related environmental applications Edition of 2026
FOREWORD
TABLE OF CONTENTS
INTRODUCTION
CHAPTER 1
     1.1 Components of WMO global infrastructure
     1.2 WMO Integrated Global Observing System (WIGOS)
          1.2.1 Weather observations
               1.2.1.1 Surface land observations
               1.2.1.2 Upper-air observations
               1.2.1.3 Weather and wind profiler radar observations
               1.2.1.4 Other ground-based remote sensing observations
               1.2.1.5 Aircraft meteorological observations
               1.2.1.6 Surface marine observations
               1.2.1.7 Observations from meteorological satellites
          1.2.2 Atmospheric composition observations
          1.2.3 Hydrological observations
          1.2.4 Cryosphere observations
          1.2.5 Space weather observations
          1.2.6 Climate observations
          1.2.7 Ocean observations
CHAPTER 2
     2.1 Definition of the meteorological satellite service (MetSat) and its frequency allocations
          2.1.1 General concept of MetSat satellite systems
     2.2 MetSat systems using geostationary (GSO) satellites
          2.2.1 GSO MetSat raw image sensor data transmissions
          2.2.2 GSO MetSat data dissemination
               2.2.2.1 Stretched Visible Infrared Spin Scan Radiometer (S-VISSR)
               2.2.2.2 Geostationary Operational Environmental Satellites (GOES) Variable (GVAR)
               2.2.2.3 Weather Facsimile (WEFAX)
               2.2.2.4 Low Rate Information Transmission (LRIT)
               2.2.2.5 High Rate Information Transmission (HRIT)
          2.2.3 GSO MetSat Data Collection Systems (DCS)
               2.2.3.1 Basic general partitioning and sharing conditions for the band 401-403 MHz
     2.3 MetSat systems using non-GSO satellites
          2.3.1 Non-GSO MetSat raw instrument data transmissions
               2.3.1.1 Non-GSO MetSat raw instrument data transmissions using the band 25.5-27 GHz
          2.3.2 Non-GSO MetSat data dissemination
               2.3.2.1 Non-GSO MetSat data dissemination using the band 1 698-1 710 MHz
                    2.3.2.1.1 Automatic Picture Transmission (APT)
                    2.3.2.1.2 Low Resolution Picture Transmission (LRPT)
                    2.3.2.1.3 High Resolution Picture Transmission (HRPT)
               2.3.2.2 Non-GSO MetSat data dissemination using the band 7 750-7 900 MHz
          2.3.3 Non-GSO MetSat Data Collection Systems (DCSs)
     2.4 Alternative data dissemination mechanisms
CHAPTER 3
     3.1 Introduction
          3.1.1 Allocated RF bands
          3.1.2 Meteorological functions of the MetAids service
     3.2 Examples of MetAids sensing systems
          3.2.1 Radiosondes
          3.2.2 Dropsondes
     3.3 Factors influencing the characteristics of the MetAids systems
          3.3.1 Ground-based receiver antenna system
          3.3.2 Ground-based processing system
          3.3.3 Expendable sensing packages
     3.4 Characteristics of meteorological observations required from the MetAids service
          3.4.1 Characteristics of radiosondes
          3.4.2 Characteristics of ozonesondes
     3.5 Variations in MetAids service operations
          3.5.1 Variations in upper wind patterns and their impact on radiosonde operations
          3.5.2 Variations in network density
          3.5.3 Use of the 401-406 MHz band
          3.5.4 Use of the 1 668.4-1 700 MHz band
          3.5.5 Requirements for retaining both bands
     3.6 Future trends
CHAPTER 4
     4.1 Introduction
          4.1.1 Meteorological radar types
          4.1.2 Radar equation for Meteorological application
     4.2 Weather radars
          4.2.1 User requirements
          4.2.2 Weather radar networks
          4.2.3 Operational aspects of reflectivity
          4.2.4 Weather radars emission schemes, scanning strategies and operational modes
               4.2.4.1 Emission schemes
               4.2.4.2 Noise calibration
               4.2.4.3 Operational modes for meteorological radar
                    4.2.4.3.1 Clear air mode
                    4.2.4.3.2 Precipitation mode
               4.2.4.4 Fixed echo elimination
          4.2.5 Doppler radars
          4.2.6 Dual-polarization radars
          4.2.7 Conventional meteorological radar base data products
               4.2.7.1 Base reflectivity
               4.2.7.2 Mean radial velocity
               4.2.7.3 Spectrum width
               4.2.7.4 Dual polarization meteorological radar products
                    4.2.7.4.1 Differential reflectivity
                    4.2.7.4.2 Correlation coefficient
                    4.2.7.4.3 Linear depolarization ratio
                    4.2.7.4.4 Differential phase
               4.2.7.5 Derived data products
          4.2.8 Antenna pattern and antenna dynamics
               4.2.8.1 Antenna patterns
               4.2.8.2 Volume scan antenna movement
               4.2.8.3 Other antenna movement strategies
          4.2.9 Present and future spectrum requirements
               4.2.9.1 Weather radar frequency bands
               4.2.9.2 Attenuation
               4.2.9.3 Maximum unambiguous range and velocity estimates
               4.2.9.4 Echo coherency
               4.2.9.5 Resonance effects – quantitative intensity measurements
               4.2.9.6 Conclusions
          4.2.10 Vulnerabilities of weather radars
               4.2.10.1 Types of possible interference
               4.2.10.2 Impact of constant interference
                    4.2.10.2.1 Geographical coverage
                    4.2.10.2.2 Rain rate
                    4.2.10.2.3 Wind measurement
               4.2.10.3 Impact of persistent pulsed interference
               4.2.10.4 Interference and coexistence between Meteorological radar and other radar systems
               4.2.10.5 Interference to C-band radars from WAS/RLAN
               4.2.10.6 Use of the 5.4 GHz band for C-Band radars
               4.2.10.7 Interference from wind farms
                    4.2.10.7.1 Masking
                    4.2.10.7.2 Clutter
                    4.2.10.7.3 Backscattered energy from turbulent eddies
                    4.2.10.7.4 Examples of wind turbine clutter
                    4.2.10.7.5 Impact of WTC on meteorological radar operations and forecasting accuracy
          4.2.11 Vulnerabilities of systems sharing spectrum with weather radars
          4.2.12 Future trends
               4.2.12.1 Hardware and algorithms improvements
               4.2.12.2 Solid state technology
     4.3 Wind profiler radars (WPRs)
          4.3.1 User requirements
          4.3.2 Operational and frequency aspects
          4.3.3 Present and future spectrum requirements
          4.3.4 Sharing aspects of wind profilers
     4.4 Oceanographic High Frequency Radar
CHAPTER 5
     5.1 Introduction
     5.2 Passive microwave radiometry sensing
          5.2.1 Spectrum requirements
          5.2.2 Observation of Earth’s surface features
               5.2.2.1 Observation over ocean surfaces
               5.2.2.2 Observation over land surfaces
               5.2.2.3 Auxiliary parameters for other remote sensing instruments
          5.2.3 Performance parameters
               5.2.3.1 Radiometric sensitivity
               5.2.3.2 Radiometer threshold (P
               5.2.3.3 Geometric resolution
               5.2.3.4 Integration time
          5.2.4 Typical operating conditions of passive sensors
               5.2.4.1 Low Earth-orbiting satellites
               5.2.4.2 Geostationary satellites
          5.2.5 Observation geometries
               5.2.5.1 Conical scan
               5.2.5.2 Cross-track scan
               5.2.5.3 Push-broom
          5.2.6 Performance and interference criteria
          5.2.7 Three-dimensional measurement of atmospheric parameters
               5.2.7.1 Passive microwave atmospheric vertical sounders
               5.2.7.2 Mechanism of vertical atmospheric sounding
               5.2.7.3 Utilization of vertical atmospheric sounding
               5.2.7.4 Characteristics of nadir-looking passive sensors operating in the 60 GHz range
               5.2.7.5 Passive microwave limb sounders
               5.2.7.6 Vulnerability to interference of passive microwave sounders
          5.2.8 Cold sky calibration
     5.3 Active sensors
          5.3.1 Introduction
          5.3.2 Synthetic aperture radars (SARs)
          5.3.3 Altimeters
          5.3.4 Scatterometers
          5.3.5 Precipitation radars
          5.3.6 Cloud profile radars
          5.3.7 Radar sounders
          5.3.8 Sensor interference and performance criteria
          5.3.9 Power flux-density (pfd) levels
CHAPTER 6
     6.1 Definition of space weather and its associated radio communication service
     6.2 Space weather observations
          6.2.1 Phenomena observed
          6.2.2 The requirement for space weather observations
          6.2.3 Space weather sensor systems using radio spectrum
               6.2.3.1 Solar observations
                    6.2.3.1.1 Solar flux
                    6.2.3.1.2 Solar spectrograph
                    6.2.3.1.3 Heliograph
               6.2.3.2 Heliospheric observations
                    6.2.3.2.1 Interplanetary scintillations (IPS)
               6.2.3.3 Ionospheric observations
                    6.2.3.3.1 Ionosondes
                    6.2.3.3.2 Incoherent Scatter Radars
                    6.2.3.3.3 Coherent Scatter Radars
                    6.2.3.3.4 Other radars
                    6.2.3.3.5 Ionospheric tomography
                    6.2.3.3.6 Radio telescopes
                    6.2.3.3.7 Riometer
                    6.2.3.3.8 Global Navigation Satellite System (GNSS)
                    6.2.3.3.9 Very low frequency (VLF)
          6.2.4 Categorization of the RF-based sensors in regard to support of current space weather products
CHAPTER 7
     7.1 Introduction
     7.2 Data dissemination systems
     7.3 Weather-sensing Uncrewed Aircraft Systems
     7.4 Hydrological systems
     7.5 Meteorological uses of Global Navigation Satellite Systems (GNSSs)
          7.5.1 Accurate location and timing of meteorological observing platforms
          7.5.2 Atmospheric and surface measurements
     7.6 Lightning detection systems
     7.7 Ground-based microwave radiometers
     7.8 Microwave Radio Attenuation systems
Annex  Acronyms and abbreviations
     A.1 Acronyms and abbreviations commonly used in meteorology
     A.2 Other acronyms and abbreviations used in this Handbook