THE NERC MST RADAR FACILITY AT ABERYSTWYTH
An overview of the radar measurement technique and of the meanings of the data products are given here. The files contain altitude profiles (from approximately 2 - 20 km for the ST mode, and from approximately 58 - 96 km for the M mode, both at 150 m intervals) of the eastward, northward and upward components of the wind velocity and the following radar return parameters: vertical beam signal power, vertical beam spectral width, vertical beam beam-broadening corrected spectral width, and aspect sensitivity. The time separation between the profiles is typically a few minutes. A radar-derived tropopause altitude and sharpness is given for each set of profiles.
Click here to find out about the contents of other files.
Availability Data processed by version-3 software are currently available from 20th June 2006 until the present. The entire archive will eventually be reprocessed. Please contact the NERC MST Radar Facility Project Scientist if you would like v3 data for earlier dates.
File naming convention:
 |
YYYY | |
is a 4-digit year [1990 - ] |
| MM | is a 2-digit month [01 - 12] | ||
| DD | is a 2-digit day [01 - 31] | ||
| AA | is the altitude mode ['st': approximately 2 - 20 km | 'm': approximately 58 - 96 km] | ||
| RRR | is the range resolution (m) [150 | 300 | 600 | 1200 | 2400 | 4800] | ||
| .nc | represents that this is a netCDF file |
i.e. radar-mst_capel-dewi_20060620_st300_cartesian_v3.nc contains 300 m resolution Cartesian data over the ST altitude range for 20th June 2006.
Click here for the background to the file naming convention.
File location:
ST-mode: /badc/mst/data/mst-products-v3/st-mode/cartesian/
M-mode: /badc/mst/data/mst-products-v3/m-mode/cartesian/
Click here for the location of other files.
Archiving convention: YYYY/MM
Click here for a further explanation.
netCDF File Structure using the st300 file for 20th June 2006 as an example - click here for an explanation
- List of Global attributes - Click on the name to view the value
- char Conventions
- char title
- char institution
- char source
- char history
- char references
- char comment
- short data_year
- short data_month
- short data_day
- char data_altitude_mode
- float data_range_resolution_m
- short data_range_resolution_number
- short data_bottom_range_gate_number
- short data_top_range_gate_number
- float radar_frequency_MHz
- float radar_wavelength_m
- char radar_transmitters
- float radar_peak_transmitted_power_kW
- char radar_antenna_type
- float radar_antenna_side_length_m
- float radar_beam_one_way_half_power_half_width_degrees
- char radar_location_name
- float radar_latitude_degrees_north
- float radar_longitude_degrees_east
- float radar_altitude_above_mean_sea_level_m
- char radar_british_national_grid_reference
- short signal_processing_version_number
- short signal_processing_sub_version_number
- float sig_lims_min_peak_smooth_psd_to_noise_dB_to_flag
- float cart_horiz_wind_zen_angle_deg
- float cart_horiz_wind_primary_azi_angle_deg
- short cart_apply_theta_s_corr_to_horiz_wind
- float cart_max_compl_beam_horiz_vel_diff_mps
- float cart_max_theta_s_horiz_wind_corr_fact
- float cart_theta_s_high_zen_angle_deg
- float cart_theta_s_low_zen_angle_deg
- float cart_tpause_grad_intvl_m
- float cart_asp_sens_high_zen_angle_deg
- char title
- List of Variables - Click on a name to view the corresponding attributes
- float time (time)
- float altitude (altitude)
- float latitude ()
- float longitude ()
- byte horizontal_wind_components_are_reliable (time, altitude)
- short horizontal_wind_components_reliability_details (time, altitude)
- float eastward_wind (time, altitude)
- float northward_wind (time, altitude)
- byte horizontal_wind_complementary_beam_variability (time, altitude)
- float horizontal_wind_theta_s_compensation_factor (time, altitude)
- byte vertical_beam_data_are_reliable (time, altitude)
- short vertical_beam_data_reliability_details (time, altitude)
- float vertical_beam_signal_power (time, altitude)
- float vertical_beam_radial_velocity (time, altitude)
- float vertical_beam_spectral_width (time, altitude)
- byte beam_broadening_corrected_spectral_width_is_reliable (time, altitude)
- short beam_broadening_corrected_spectral_width_reliability_details (time, altitude)
- float beam_broadening_corrected_spectral_width (time, altitude)
- byte aspect_sensitivity_is_reliable (time, altitude)
- short aspect_sensitivity_reliability_details (time, altitude)
- float aspect_sensitivity (time, altitude)
- float vertical_beam_median_noise_power (time)
- float tropopause_altitude (time)
- byte tropopause_sharpness_factor (time)
- float altitude (altitude)
char Conventions = "CF-1.0"
char title = "46.5 MHz wind-profiling radar Cartesian data - st300 mode"
char institution = "
Data recorded by the Natural Environment Research Council (NERC)
Mesosphere-Stratosphere-Troposphere (MST) Radar Facility at Aberystwyth
- http://mst.nerc.ac.uk
Data processed by the Rutherford Appleton Laboratory, Space Science and
Technology Department - http://www.sstd.rl.ac.uk
Data held at the British Atmospheric Data Centre
http://badc.nerc.ac.uk/data/mst"
char source = "
The Natural Environment Research Council (NERC) Mesosphere-Stratosphere-
Troposphere (MST) Radar at Aberystwyth "
char history = "File created 2006-11-20 11:39:29 +00:00 on machine claudius"
char references = "
Basic information about the data is available at
http://badc.nerc.ac.uk/data/mst
More detailed information about the data is available at
http://mst.nerc.ac.uk"
char comment = "
The Natural Environment Research Council (NERC) Mesosphere-Stratosphere-
Troposphere (MST) Radar at Aberystwyth (UK) is a 46.5 MHz
wind-profiling instrument. It transmits short pulses of radio waves
which are scattered back to it from atmospheric targets. The distance
of a target from the instrument is determined by the time delay
between the transmission and reception of a pulse. The main targets
are metre-scale refractive index irregularities, which are referred to
as clear-air targets (the term does not necessarily imply clear-sky
conditions as the radar is able to see through clouds). Hydrometeors,
aircraft, and ground-based objects can also give rise to radar
returns. The receiver signal is occasionally contaminated by
interference. The refractive index irregularities are caused by
variations in atmospheric humidity (within the lowest 10 km of the
atmosphere), in atmospheric density (within the lowest few 10s of km)
and in free electron density (above 50 km). The radar return signal
power is typically proportional to the square of the mean vertical
gradient of the (potential) refractive index and inversely
proportional to the square of the range of the clear-air targets from
the radar. The refractive index irregularities are assumed to be
advected with the wind. Consequently the radial velocity, i.e. the
component of the wind vector along the radar beam pointing direction,
can be inferred from the Doppler shift of the radar return
signal. Atmospheric turbulence gives rise to variability in the radial
velocity when observed over a time scale of a few tens of
seconds. However, as a result of the radar\'s finite beam width, the
observed spread tends to be dominated by a beam-broadening component,
which is proportional to the horizontal wind speed. Consequently it
becomes increasingly difficult to infer turbulence intensities as the
wind speed increases.
The radar receiver signal is sampled at 1.0 us intervals following
the transmission of a pulse. This corresponds to sampling at 150.0 m
intervals in range from the radar. It is necessary to sample both the
in-phase (I) and quadrature (Q) components of the receiver signal
(i.e. complex values) in order to allow both the magnitude and the
sign of the Doppler shift to be inferred. In the m-mode samples are
recorded between ranges of approximately 60 and 90 km. In the st-mode
samples are recorded between ranges of approximately 2 and 20 km. It
is possible to operate the radar in mst-mode so that both altitude
ranges are sampled simultaneously. The range resolution of the radar
returns is determined by the length of the transmitter pulse (not by
the sampling interval), to which the receiver bandwidth must be
matched. The range resolution can be increased by using complementary
coding. This requires the phase of sub-lengths of the transmitter
pulse to be offset by either 0 or 180 degrees according to a set
coding pattern. The range resolution is then determined by the
sub-length of the transmitter pulse (to which the receiver bandwidth
is matched).
No attempt is made to derive radar return signal parameters until
samples have been acquired for a large, pre-determined number of
pulses - typically covering a few tens of seconds. The term dwell is
used to refer to this collection interval or to range profiles of any
of the data products associated with it. A dwell initially consists of
a complex time series, for each range gate, of I and Q samples which
are separated in time by the inter pulse period (of the order of a
millisecond). The nature of the samples changes only slowly from pulse
to pulse and so coherent integration is applied - for each range gate,
groups of consecutive samples are summed together. The number of
complex samples in the resulting time series is thus reduced, and the
time interval between them is increased, by a factor equal to the
number of coherent integrations (typically of the order of a few
hundred). The time interval between the new samples (typically of the
order of 0.1 s) determines the Nyquist velocity (typically of the
order of 10 m/s), the maximum radial velocity that can be
unambiguously determined. Decoding must be applied to the coherently
integrated samples if a complementary transmitter code has been
used. For each range gate, a complex Doppler frequency spectrum is
derived by applying a weighting window to the complex time series data
followed by a discrete Fourier transform. This spectrum is multiplied
by its complex conjugate to give a power spectrum. Doppler frequencies
are converted into Doppler velocities by multiplying by half the radar
wavelength. The sign must be changed so that movement away from the
radar (which gives rise to a negative frequency shift) is represented
by a positive velocity. If desired, consecutively-observed Doppler
velocity power spectra may be incoherently integrated by adding them
together. This increases the detectability of signals. In general a
Doppler velocity power spectrum contains one or more signal components
superimposed on a background of nominally white noise. The power
spectral densities (PSDs) of the velocity bins around zero velocity
(the number depends on the data weighting window used) are typically
contaminated by dc biases in the time-series samples. The values must
be replaced by linearly interpolating between the PSDs of adjacent
velocity bins. The noise power is dominated by broad-band lower-VHF
cosmic radiation, which undergoes a diurnal variation by a factor of
approximately 2.
For each Doppler velocity power spectrum, the noise power spectral
density (PSD) is determined by the statistical method of Hildebrand
and Sekhon (1974). The noise power is equal to the noise PSD summed
across the width of the spectrum. The velocity bin limits of the
strongest signal component are determined by first locating the peak
value of the running-mean-smoothed PSD. The smoothed PSD is then
followed to either side until one of the following conditions is
encountered: the smoothed PSD has dropped below the noise PSD, the
smoothed PSD has dropped below a set fraction of the peak value, or a
local minimum is encountered (and the smoothed PSD is below a set
fraction of the peak value). The final criterion is particularly
important under stratiform precipitation conditions in order to
separate partially-overlapping clear-air and hydrometeor signal
components. The PSDs within the signal limits first have the noise PSD
subtracted and are then compensated for the low-pass-filtering effect
of coherent integration. The zeroth (m0), first (m1) and second (m2)
order moments (of the corrected PSDs within the signal limits) are
calculated in order to derive the signal power (m0), the radial
velocity (m1/m0) and the spectral width (sqrt[(m2/m0) -
(m1/m0)**2]). For st-mode observations it is desirable to identify
more than one signal component per spectrum (typically two). A radial
continuity algorithm is then used to identify the primary signal
component for each range gate, i.e. that which leads to the most
likely overall clear-air radar return profile. A second attempt may be
made to identify the primary signal components if the first profile is
deemed to be contaminated by interference. A final attempt is made to
improve the selection of primary signal components for the lowest
range gates in case of contamination by hydrometeor
returns. Subsequently attention is confined to the primary signal
components. Nevertheless, the radar return parameters for the
non-primary signal components are saved in the radial data files as
they may contain scientifically useful information, e.g. concerning
precipitation.
For wind-profiling purposes, MST radar observations are cycled
through a sequence of dwells with different beam pointing
directions. The radial velocity for each dwell is assumed to represent
the the dot product of the three-dimensional wind vector and a unit
vector along the beam pointing direction. The radial velocity observed
by a vertical beam (i.e. a dwell with a beam pointing zenith angle of
zero) is therefore assumed to be equal to the vertical component of
the wind. The radial velocity observed by an off-vertical beam (i.e. a
dwell with a small, non-zero beam pointing zenith angle) is assumed to
represent the vector sum of the vertical component of the wind
multiplied by the cosine of the zenith angle, and the component of the
horizontal wind along the the radar beam pointing azimuth multiplied
by the sine of the zenith angle. Consequently a component of the
horizontal wind can be derived for each vertical/off-vertical beam
pair. When more than one vertical beam observation is made per cycle,
that closest in time to the off-vertical beam observation is used for
deriving the horizontal wind components. When combining vertical and
off-vertical beam radial velocity components, vertical beam data are
taken from those range gates which are most closely matched in
altitude to the off-vertical beam range gates. A time continuity
algorithm is applied to the horizontal wind components for the
off-vertical beams, and to the vertical wind components for the
vertical beams, as a further test for reliability. Time continuity is
first established uni-directionally, i.e. by comparing the
observations to be flagged only with those made at earlier times. This
allows wind-profile data to be made available with only a short time
delay. However, the process is repeated as soon as there are
sufficient subsequent observations to allow bi-directional flagging to
be applied. The overall reliability of signal components requires them
to have passed both radial continuity (when the tests have been made)
and time continuity tests.
In order to derive Cartesian components of the wind vector,
observations must be made in the vertical direction and at an
off-vertical angle in two orthogonal azimuths. A typical cycle of
observation includes many more beam pointing directions. The
availability of additional information allows improved wind component
estimates to be made. Attention is confined to the horizontal wind
components (derived from vertical/off-vertical beam pairs, as
described above) arising from off-vertical beam observations made with
a single, pre-determined zenith angle (indicated by the global
attribute cart_horiz_wind_zen_angle_deg; this is typically 6.0
degrees). If observations are made more than once per cycle with the
same off-vertical beam, only those from the first instance are
considered. If observations have been made with the complementary
off-vertical beam (i.e. that with the same zenith angle but with an
azimuth angle which differs by 180 degrees), the horizontal wind
components are averaged (if they are both flagged as being
reliable). The difference between them gives a measure of reliability
of the averaged value. It gives an indication of the degree to which a
fundamental assumption of the wind-profiling technique is valid: that
the wind field is stationary over the time taken to complete a full
cycle of observation (typically a few minutes) and over the horizontal
distance separating the radar observation volumes for the different
beam pointing directions (of the order of 2 km at 10 km altitude). If
the difference exceeds a predefined value (given by the global
attribute cart_max_compl_beam_horiz_vel_diff_mps), the averaged
horizontal wind component is flagged as being unreliable. The
horizontal wind complementary beam variability values stored in the
Cartesian files represent the root of the sum of the squares of the
values for the primary and secondary (i.e. orthogonal) radar
azimuths. The primary radar azimuth is given by the global attribute
cart_horiz_wind_primary_azi_angle_deg.
Owing to the aspect sensitivity of radar returns (i.e. to the fact
that the radar return signal power often decreases with increasing
zenith angle) and to the finite radar beam width, the effective
pointing angle for an off-vertical beam is typically slightly closer
to the vertical than the nominal zenith angle. This leads to slight
underestimates of the magnitudes of the horizontal wind
components. The amount can quantified, and the horizontal wind
components are compensated, through consideration of the theta_s
parameter, which is derived from the ratio of the radar return signal
powers at two non-zero zenith angles (Hooper and Thomas, 1995). If
observations are made more than once per cycle at these zenith angles
(given by the global attributes cart_theta_s_low_zen_angle_deg and
cart_theta_s_high_zen_angle_deg) the radar signal powers are first
averaged. Finally the horizontal wind components are rotated from
their native azimuths (i.e. from cart_horiz_wind_primary_azi_angle_deg
and an orthogonal direction) to give northward and eastward
components. A single flag indicates the reliability of both horizontal
wind components.
The characteristics of thirty-minute-average wind-profile data
derived from this (version 3) processing scheme have been evaluated by
the Met Office. The random errors, evaluated over 7 days, are
typically in the range 1.0 - 3.0 m/s for altitudes between 2 and 15 km
and in the range 3.0 - 4.0 m/s between 15 and 20 km. The number of
reported winds begins to decrease with increasing altitude in the
upper altitude range. Winds are reported at least 80% of the time up
to 18 km but no more than 30% of the time at 20 km. Comparisons have
also been made against the winds from the Met Office's numerical
weather prediction model. The magnitudes of the component biases are
less than 0.5 m/s at all altitudes. The root mean square component
differences are in the range 2.0 - 3.0 m/s. The directional bias is
approximately 1.0 degree and the magnitude of the speed bias is less
than 1.0 m/s. These values are comparable to those for radiosonde
data.
The vertical wind component (for which the standard name is
upward_air_velocity) is given by the radial velocity of the vertical
beam observation. The accuracy of these estimates is difficult to
estimate owing to the lack of comparable measurements. The value of
0.2 m/s represents the typical magnitude of fluctuations (about zero)
under quiet conditions. Mountain wave conditions give rise to peak
values of the order of 1.0 m/s and convective conditions to peak
values of the order of 10.0 m/s. When more than one vertical beam
observation is made per cycle, only the first instance is
considered. The vertical beam radar return signal power and spectral
width also relate to this instance. A single flag indicates the
reliability of all three vertical beam products. Vertical beam data
products are taken from those range gates which are most closely
matched in altitude to the range gates for the the off-vertical angle
(cart_horiz_wind_zen_angle_deg) used for the horizontal wind
estimation. This is true of all data products stored in the Cartesian
files. Changes in the vertical beam radar return signal power from the
upper-troposphere/lower-stratosphere region tends to be closely
related to those in the vertical temperature gradient. This allows
both the altitude and the sharpness of the tropopause to be determined
by the method of Hooper and Arvelius (2000).
The spectral width of vertical beam radar returns tends to be
dominated by the beam-broadening component, which is equal to the
product of the horizontal wind speed and of the radar beam two-way
half-power half-width. The beam broadening corrected spectral width
values represent the the root of the difference between the squares of
the observed widths and of the beam-broadening components. It has its
own reliability flag. The accuracy of 0.1 m/s is estimated from the
typical spread of those beam-broadening component values which exceed
the observed values. No beam broadening corrected values can be
calculated under such conditions.
In addition to quantifying the aspect sensitivity of radar returns
through the theta_s parameter, a second, simpler measure is given by
the ratio of the signal power observed by the vertical beam to that
observed at an off-vertical angle (given by the global attribute
cart_asp_sens_high_zen_angle_deg, which is typically 6.0
degrees). Signal powers are first averaged when there is more than one
observation per cycle for each of the required zenith angles. Small
values of aspect sensitivity (< 5 dB) imply backscatter from
quasi-isotropic refractive index irregularities, which suggests that
the atmosphere is well mixed. Large values (> 10 dB) imply that the
coherence length of the refractive index irregularities is far greater
in the horizontal than in the vertical. Such structures are consistent
with the atmosphere being not well mixed. The aspect sensitivity tends
to be low in the troposphere and high in the stratosphere although
this is not always the case. The aspect sensitivity has its own
reliability flag."
short data_year = 2006
short data_month = 6
short data_day = 20
char data_altitude_mode = "st"
float data_range_resolution_m = 300.0
short data_range_resolution_number = 2
short data_bottom_range_gate_number = 18
short data_top_range_gate_number = 147
float radar_frequency_MHz = 46.5
float radar_wavelength_m = 6.45
char radar_transmitters = "5 Tycho Technology WPT-50s"
float radar_peak_transmitted_power_kW = 160.0
char radar_antenna_type = "20 by 20 array of 4-element Yagi aerials with 0.85 wavelength spacing"
float radar_antenna_side_length_m = 104.12
float radar_beam_one_way_half_power_half_width_degrees = 1.5
char radar_location_name = "Capel Dewi (near Aberystwyth, UK)"
float radar_latitude_degrees_north = 52.42
float radar_longitude_degrees_east = -4.01
float radar_altitude_above_mean_sea_level_m = 50.0
char radar_british_national_grid_reference = "SN637826"
short signal_processing_version_number = 3
short signal_processing_sub_version_number = 2
float sig_lims_min_peak_smooth_psd_to_noise_dB_to_flag = 10.0
float cart_horiz_wind_zen_angle_deg = 6.0
float cart_horiz_wind_primary_azi_angle_deg = 27.5
short cart_apply_theta_s_corr_to_horiz_wind = 1
float cart_max_compl_beam_horiz_vel_diff_mps = 10.0
float cart_max_theta_s_horiz_wind_corr_fact = 1.5
float cart_theta_s_high_zen_angle_deg = 6.0
float cart_theta_s_low_zen_angle_deg = 4.2
float cart_tpause_grad_intvl_m = 1800.0
float cart_asp_sens_high_zen_angle_deg = 6.0
List of Variable attribute values
- float time (time)
- standard_name = "time"
- long_name = "UTC"
- units = "seconds since 2006-06-20 00:00:00 +00:00"
- axis = "T"
- comment = "
Times refer to the start of the first dwell (for the observation
mode) within the cycle." - long_name = "UTC"
- float altitude (altitude)
- standard_name = "altitude"
- long_name = "Altitude above mean sea level"
- units = "m"
- axis = "Z"
- comment = " The altitude of the centre of a range gate above mean sea level."
- long_name = "Altitude above mean sea level"
- float latitude ()
- standard_name = "latitude"
- long_name = "Radar latitude"
- units = "degrees_north"
- axis = "Y"
- long_name = "Radar latitude"
- float longitude ()
- standard_name = "longitude"
- long_name = "Radar longitude"
- units = "degrees_east"
- axis = "X"
- long_name = "Radar longitude"
- byte horizontal_wind_components_are_reliable (time, altitude)
- long_name = "Horizontal wind data reliability flag"
- units = "1"
- flag_values = 0 1 b
- flag_meanings = "data_are_not_reliable data_are_reliable"
- coordinates = "latitude longitude"
- comment = "
The reliability flag and reliability details apply to variables
eastward_wind, northward_wind, horizontal_wind_theta_s_compensation_factor
and horizontal_wind_complementary_beam_variability.
It is important to use the reliability flag to select useful data
points as, in most cases, unreliable values are not replaced with
missing datum values." - units = "1"
- short horizontal_wind_components_reliability_details (time, altitude)
- long_name = "Horizontal wind data reliability details"
- units = "1"
- coordinates = "latitude longitude"
- comment = "
The reliability flag and reliability details apply to variables
eastward_wind, northward_wind, horizontal_wind_theta_s_compensation_factor
and horizontal_wind_complementary_beam_variability.
The details by means of which the reliability of a data product is
determined are coded bitwise into a 14-bit unsigned integer (albeit
stored as a 16-bit signed integer) for which bit 00 is the least
significant bit. Not all bits are used by every data product.
bit 00: 1 if the signal component is available
bit 01: 1 if the peak smoothed power spectral density (PSD) is greater
than sig_lims_min_peak_smooth_psd_to_noise_dB_to_flag (a
global attribute) above the noise PSD
bit 02: 1 if the signal component belongs to a radial chain
bit 03: 1 if the signal component fits overall radial continuity
bit 04: 1 if a secondary signal component belongs to a radial chain
bit 05: 1 if the signal component has passed a uni-directional time
continuity test
bit 06: 1 if the signal component has passed a bi-directional time
continuity test
bit 07: 1 if a complementary beam exists
bit 08: 1 if the complementary horizontal wind components have both passed
lower order reliability tests
bit 09: 1 if the complementary horizontal wind components have both passed
lower order reliability tests for the orthogonal azimuth
bit 10: 1 if the complementary horizontal wind components differ by
less than cart_max_compl_beam_horiz_vel_diff_mps (a global attribute)
bit 11: 1 if the theta_s compensation factor can be applied for
horizontal wind components
bit 12: 1 if the theta_s compensation factor has been applied to the
horizontal wind components
bit 13: 1 if the beam-broadening correction of spectral width results
in a usable value" - units = "1"
- byte horizontal_wind_complementary_beam_variability (time, altitude)
- long_name = "Complementary beam horizontal velocity variability"
- units = "m s-1"
- missing_value = -99b
- _FillValue = -99b
- coordinates = "latitude longitude"
- comment = "
These values are for diagnostic purposes only. Refer to the global
attribute comment for an explanation." - units = "m s-1"
- float horizontal_wind_theta_s_compensation_factor (time, altitude)
- long_name = "Scale factor applied to horizontal wind components to compensate for the effects of aspect sensitivity"
- units = "1"
- missing_value = -9999.0f
- _FillValue = -9999.0f
- coordinates = "latitude longitude"
- comment = "
These values are for diagnostic purposes only. They represent the
scale factors by which the magnitudes of horizontal wind components
have been compensated for the effects of aspect sensitivity. " - units = "1"
- byte vertical_beam_data_are_reliable (time, altitude)
- long_name = "Vertical beam data reliability flag"
- units = "1"
- flag_values = 0 1 b
- flag_meanings = "data_are_not_reliable data_are_reliable"
- coordinates = "latitude longitude"
- comment = "
The reliability flag and reliability details apply to variables
vertical_beam_signal_power, vertical_beam_radial_velocity and
vertical_beam_spectral_width.
It is important to use the reliability flag to select useful data
points as, in most cases, unreliable values are not replaced with
missing datum values." - units = "1"
- short vertical_beam_data_reliability_details (time, altitude)
- long_name = "Vertical beam data reliability details"
- units = "1"
- coordinates = "latitude longitude"
- comment = "
The reliability flag and reliability details apply to variables
vertical_beam_signal_power, vertical_beam_radial_velocity and
vertical_beam_spectral_width.
The details by means of which the reliability of a data product is
determined are coded bitwise into a 14-bit unsigned integer (albeit
stored as a 16-bit signed integer) for which bit 00 is the least
significant bit. Not all bits are used by every data product.
bit 00: 1 if the signal component is available
bit 01: 1 if the peak smoothed power spectral density (PSD) is greater
than sig_lims_min_peak_smooth_psd_to_noise_dB_to_flag (a
global attribute) above the noise PSD
bit 02: 1 if the signal component belongs to a radial chain
bit 03: 1 if the signal component fits overall radial continuity
bit 04: 1 if a secondary signal component belongs to a radial chain
bit 05: 1 if the signal component has passed a uni-directional time
continuity test
bit 06: 1 if the signal component has passed a bi-directional time
continuity test
bit 07: 1 if a complementary beam exists
bit 08: 1 if the complementary horizontal wind components have both passed
lower order reliability tests
bit 09: 1 if the complementary horizontal wind components have both passed
lower order reliability tests for the orthogonal azimuth
bit 10: 1 if the complementary horizontal wind components differ by
less than cart_max_compl_beam_horiz_vel_diff_mps (a global attribute)
bit 11: 1 if the theta_s compensation factor can be applied for
horizontal wind components
bit 12: 1 if the theta_s compensation factor has been applied to the
horizontal wind components
bit 13: 1 if the beam-broadening correction of spectral width results
in a usable value" - units = "1"
- float vertical_beam_signal_power (time, altitude)
- long_name = "Vertical beam radar return signal power"
- units = "dB"
- estimated_accuracy = 2.0f
- missing_value = -9999.0f
- _FillValue = -9999.0f
- coordinates = "latitude longitude"
- comment = "
Powers have dimensions of W. The values are uncalibrated and are
stored in dB units, where P_dB = 10.0 * log10(P_linear_units) " - units = "dB"
- byte beam_broadening_corrected_spectral_width_is_reliable (time, altitude)
- long_name = "Vertical beam radar return spectral width corrected for beam-broadening is reliable"
- units = "1"
- flag_values = 0 1 b
- flag_meanings = "datum_is_not_reliable datum_is_reliable"
- coordinates = "latitude longitude"
- comment = "
The reliability flag and reliability details apply to variable
beam_broadening_corrected_spectral_width.
It is important to use the reliability flag to select useful data
points as, in most cases, unreliable values are not replaced with
missing datum values." - units = "1"
- short beam_broadening_corrected_spectral_width_reliability_details (time, altitude)
- long_name = "Vertical beam radar return spectral width corrected for beam-broadening reliability details"
- units = "1"
- coordinates = "latitude longitude"
- comment = "
The reliability flag and reliability details apply to variable
beam_broadening_corrected_spectral_width.
The details by means of which the reliability of a data product is
determined are coded bitwise into a 14-bit unsigned integer (albeit
stored as a 16-bit signed integer) for which bit 00 isthe least
significant bit. Not all bits are used by every data product.
bit 00: 1 if the signal component is available
bit 01: 1 if the peak smoothed power spectral density (PSD) is greater
than sig_lims_min_peak_smooth_psd_to_noise_dB_to_flag (a
global attribute) above the noise PSD
bit 02: 1 if the signal component belongs to a radial chain
bit 03: 1 if the signal component fits overall radial continuity
bit 04: 1 if a secondary signal component belongs to a radial chain
bit 05: 1 if the signal component has passed a uni-directional time
continuity test
bit 06: 1 if the signal component has passed a bi-directional time
continuity test
bit 07: 1 if a complementary beam exists
bit 08: 1 if the complementary horizontal wind components have both passed
lower order reliability tests
bit 09: 1 if the complementary horizontal wind components have both passed
lower order reliability tests for the orthogonal azimuth
bit 10: 1 if the complementary horizontal wind components differ by
less than cart_max_compl_beam_horiz_vel_diff_mps (a global attribute)
bit 11: 1 if the theta_s compensation factor can be applied for
horizontal wind components
bit 12: 1 if the theta_s compensation factor has been applied to the
horizontal wind components
bit 13: 1 if the beam-broadening correction of spectral width results
in a usable value" - units = "1"
- byte aspect_sensitivity_is_reliable (time, altitude)
- long_name = "Radar return aspect sensitivity is reliable"
- units = "1"
- flag_values = 0 1 b
- flag_meanings = "datum_is_not_reliable datum_is_reliable"
- coordinates = "latitude longitude"
- comment = "
The reliability flag and reliability details apply to variable
aspect_sensitivity.
It is important to use the reliability flag to select useful data
points as, in most cases, unreliable values are not replaced with
missing datum values." - units = "1"
- short aspect_sensitivity_reliability_details (time, altitude)
- long_name = "Radar return aspect sensitivity reliability details"
- units = "1"
- coordinates = "latitude longitude"
- comment = "
The details by means of which the reliability of a data product is
determined are coded bitwise into a 14-bit unsigned integer (albeit
stored as a 16-bit signed integer) for which bit 00 is the least
significant bit. Not all bits are used by every data product.
bit 00: 1 if the signal component is available
bit 01: 1 if the peak smoothed power spectral density (PSD) is greater
than sig_lims_min_peak_smooth_psd_to_noise_dB_to_flag (a
global attribute) above the noise PSD
bit 02: 1 if the signal component belongs to a radial chain
bit 03: 1 if the signal component fits overall radial continuity
bit 04: 1 if a secondary signal component belongs to a radial chain
bit 05: 1 if the signal component has passed a uni-directional time
continuity test
bit 06: 1 if the signal component has passed a bi-directional time
continuity test
bit 07: 1 if a complementary beam exists
bit 08: 1 if the complementary horizontal wind components have both passed
lower order reliability tests
bit 09: 1 if the complementary horizontal wind components have both passed
lower order reliability tests for the orthogonal azimuth
bit 10: 1 if the complementary horizontal wind components differ by
less than cart_max_compl_beam_horiz_vel_diff_mps (a global attribute)
bit 11: 1 if the theta_s compensation factor can be applied for
horizontal wind components
bit 12: 1 if the theta_s compensation factor has been applied to the
horizontal wind components
bit 13: 1 if the beam-broadening correction of spectral width results
in a usable value" - units = "1"
- float vertical_beam_median_noise_power (time)
- long_name = "Median spectral noise power for vertical beam profile"
- units = "dB"
- estimated_accuracy = 2.0f
- missing_value = -9999.0f
- _FillValue = -9999.0f
- coordinates = "latitude longitude"
- comment = "
Powers have dimensions of W. The values are uncalibrated and are
stored in dB units, where P_dB = 10.0 * log10(P_linear_units) " - units = "dB"
- float tropopause_altitude (time)
- standard_name = "tropopause_altitude"
- long_name = "Radar-derived tropopause altitude"
- units = "m"
- estimated_accuracy = 300.0f
- missing_value = -9999.0f
- _FillValue = -9999.0f
- coordinates = "latitude longitude"
- long_name = "Radar-derived tropopause altitude"
- byte tropopause_sharpness_factor (time)
- long_name = "Radar-derived tropopause sharpness factor"
- units = "1"
- missing_value = -99b
- _FillValue = -99b
- flag_values = 0 1 2 3b
- flag_meanings = "indefinite lower_intermediate upper_intermediate definite"
- coordinates = "latitude longitude"
- units = "1"