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Tip
These examples show how to extract data

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Tip
These conditions are combined together by the logical AND operator. So a row of data is only added to the results when all the conditions match.

Filter by keys from header section

Accessing the header section is fast since the message data does not have to be expanded.

Filter by message index

Filter only the first message from the file (message indexing starts at 1):

Code Block
message_index: 1

Filter by message index list

Filter only message No 1, 2 and 10 from the file:

Code Block
message_index: 1/2/10

Filter by date and time

Note
Please note that temporal filtering is based on the first date and time values present in the data section of the BUFR message/subset.

Filter by single date and time

Here we select only messages/subsets with a given date and time:

Code Block
data_mode: window date: 20090123 time: 13 window: 0

Filter by time only

The date component can be omitted:

Code Block
data_mode: window time: 13 window: 0

Filter by time window

Here we set a 1 minute time window of either side of the specified date and time:

Code Block
data_mode: window date: 20090123 time: 13 window: 1

Filter by period

Here we select the messages/subsets within the given time period:

Code Block
data_mode: period date_1: 20090123 time_1: 1258 date_2: 20090123 time_2: 1301

Filter by area

Note
Please note that location filtering is based on the first location values present in the data section of the BUFR message/subset.

This is how to select messages in a given area:

Code Block
west: -10 east: 5 north: 60 south: 50

Filter by identifier

Filter by WMO station

Select messages/subsets by WMO identifier:

Code Block
identifier: WMO station identifier_value: 12843/12845

Note

Please note that WMO station is not a valid BUFR key but a compound one defined for your convenience. It is defined as follows:

WMO station = blockNumber * 1000 + stationNumber

Filter by other identifiers

Select aircraft messages by identifier:

Code Block
identifier: aircraftFlightNumber identifier_value: QGOBTRRA

Filter by custom conditions

A custom condition means that we can use any BUFR key from the message/subset to pose a filter condition. The examples below are all valid for classic radiosonde observation data which has multiple temperature, humidity and wind speed values on various pressure levels:

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Filter by custom condition with value

This is how to select the messages where there is any temperature value less than 280 K:

Code Block
custom_condition_count: 1 custom_key_1: airTemperature custom_operator_1: < custom_value_1: 280

Filter by custom condition with rank

This is how to select the messages where the first (rank=1) temperature value is less than 280 K:

Code Block
custom_condition_count: 1 custom_key_1: airTemperature custom_rank_1: 1 custom_operator_1: < custom_value_1: 280

Filter by custom condition with range

This is how to select the messages where the first (rank=1) temperature value is between 280-300K:

Code Block
custom_condition_count: 1 custom_key_1: airTemperature custom_rank_1: 1 custom_operator_1: in_range custom_value_1: 280/300

Filter by custom condition with excluded range

This is how to select the messages where the first (rank=1) temperature value is outside the 280-300K range:

Code Block
custom_condition_count: 1 custom_key_1: airTemperature custom_rank_1: 1 custom_operator_1: not_in_range custom_value_1: 280/300

Filter by multiple custom conditions

This is how to select the messages where the first (rank=1) temperature value is less than 280K and the first windspeed value is greater than 10 m/s:

in a tabular format using the BUFR filter interface.

Table of Contents

Sample data for the examples

This is the list of the BUFR files used in the examples below:

Anchor

	bufr_files
	bufr_files

File

Structure

Description

temp.bufr

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Classic radiosonde data. A message contains a vertical profile for a given station with various parameters (e.g. temperature, wind etc.) on a set of pressure levels.

tropical_cyclone.bufr

Anchor

	#tropical_bufr_file
	#tropical_bufr_file

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Tropical cyclone data. A message contains a full ensemble forecast with minimum mean sea level pressure and maximum wind speed values along the forecast tracks. Each ensemble member is encoded as a compressed subset within the message.

Extract a single parameter

This set of examples is based on file temp.bufr (click here for details).

Example

Filter

Results

Comments

For all the messages: extract the first non missing temperature value

Code Block
extract_data: on parameter_1: airTemperature

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By default missing values are ignored in data extraction (see option MISSING DATA)

For all the messages: extract the first (rank=1) temperature value (if missing it is ignored)

Code Block
extract_data: on parameter_1: airTemperature parameter_rank_1: 1

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Here we explicitly asked for the first temperature value. It is a missing value in many of the messages so we have less resulting rows that in the previous example.

For all the messages: extract the first (rank=1) temperature value if it is greater than 300 K

Code Block
extract_data: on parameter_1: airTemperature parameter_rank_1: 1 parameter_operator_1: > parameter_value_1: 300

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For all the messages: extract the first temperature value which is greater than 300 K

Code Block
extract_data: on parameter_1: airTemperature parameter_operator_1: > parameter_value_1: 300

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For station 78016: extract all the temperature values

Code Block
identifier_value: 78016 extract_data: on parameter_1: airTemperature extract_mode: all

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Extract with a single coordinate condition

This set of examples is based on file temp.bufr (click here for details).

Example

Filter

Results

Comments

For all the messages: extract the first temperature value which is greater than 300 K and also extract the pressure on which it occurs

Code Block
extract_data: on parameter_1: airTemperature parameter_operator_1: > parameter_value_1: 300 coordinate_condition_count: 1 coordinate_1: pressure

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Here we explicitly say that we only want the matching temperature values which appear inside a pressure block (for these messages this is always the case). By using the coordinate condition pressure will also be extracted because the EXTRACT_COORDINATE option is On by default.

For all the messages: extract the first temperature value which is greater than 300 K and the pressure is less than 950 hPa

Code Block
extract_data: on parameter_1: airTemperature parameter_operator_1: > parameter_value_1: 300 coordinate_condition_count: 1 coordinate_1: pressure coordinate_operator_1: < coordinate_value_1: 95000

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Here we further refined the coordinate condition.

For all the messages: extract the temperature value on the 500 hPa pressure level

Code Block
extract_data: on parameter_1: airTemperature coordinate_condition_count: 1 coordinate_1: pressure coordinate_operator_1: = coordinate_value_1: 50000

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For station 78016: extract the temperature on the second pressure level

Code Block
identifier_value: 78016 extract_data: on parameter_1: airTemperature coordinate_condition_count: 1 coordinate_1: pressure coordinate_rank_1: 2

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Here we restricted the filter for one station (message) only and used a rank condition for the coordinate.

For station 78016: extract the temperature on the first 6 pressure levels

Code Block
identifier_value: 78016 extract_data: on parameter_1: airTemperature coordinate_condition_count: 1 coordinate_1: pressure coordinate_rank_1: 1/2/3/4/5/6 extract_mode: all

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For coordinate rank a list of values can be specified.

For station 78016: extract the temperature on the 925, 850 and 700 hPa pressure levels

Code Block

identifier_value: 78016
extract_data: on
parameter_1: airTemperature
coordinate_condition_count: 1
coordinate_1: pressure
coordinate_operator_1: =
coordinate_value_1: 92500/85000/70000
extract_mode: all

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Extract multiple parameters

This set of examples is based on file temp.bufr (click here for details).

Example Filter Results Comments

For all the messages: extract the first wind speed and wind direction values

Code Block
extract_data: on parameter_count: 2 parameter_1: windDirection parameter_2: windSpeed

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Note
The order of the parameters in extraction must match their order of appearance in the message. Otherwise the data alignment does not work properly. In our BUFR messages `windDirection` precedes `windSpeed`, so we have to use the same ordering in the filter definition.

For all the messages: extract the first wind speed and wind direction values and also extract their pressure

Code Block
extract_data: on parameter_count: 2 parameter_1: windDirection parameter_2: windSpeed coordinate_condition_count: 1 coordinate_1: pressure

Image Added

For all the messages: extract wind speed and wind direction values on the 500 hPa pressure level

Code Block
extract_data: on parameter_1: windDirection parameter_2: windSpeed coordinate_condition_count: 1 coordinate_1: pressure coordinate_operator_1: = coordinate_value_1: 50000

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Extract with multiple (nested) coordinate conditions

This set of examples is based on file temp.bufr (click here for details).

Note
When we use multiple coordinate conditions these are regarded as nested, i.e. the first coordinate specified is the outer coordinate, the next inner coordinate is nested in it and so on. This puts a constraint on the order the coordinate conditions: the outer coordinate has to be specified first then the other coordinates must follow in the nesting order.

In the examples below we will work with two coordinates to extract radiosonde data on certain levels: pressure will be the outer coordinate and verticalSoundingSignificance, which defines the type of the pressure levels, the inner coordinate. It reflects how a pressure block is built up in our radiosonde BUFR file:

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Task Filter Results Comments

For station 78016: extract all the temperature values on standard pressure levels

Code Block

identifier_value: 78016
extract_data: on
parameter_1: airTemperature
coordinate_condition_count: 2
coordinate_1: pressure
coordinate_2: verticalSoundingSignificance
coordinate_operator_2: =
coordinate_value_2: 32
extract_mode: all

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verticalSoundingSignificance is a FLAG TABLE (bit-vector) and its value is 32 for standard pressure levels:

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For station 78016: extract all the temperature values on temperature significant levels where the pressure is less than 500 hPa

Code Block

identifier_value: 78016
extract_data: on
parameter_count: 1
parameter_1: airTemperature 
coordinate_condition_count: 2
coordinate_1: pressure
coordinate_operator_1: <
coordinate_value_1: 50000
coordinate_2: verticalSoundingSignificance
coordinate_operator_2: =
coordinate_value_2: 4/68
extract_mode: all

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Extract tropical cyclone tracks

This set of examples is based on file tropical_cyclone.bufr (click here for details).

Example

Filter

Results

For the first message (storm IN-FA) extract the storm centre pressure values along the track for ensemble number =2

Code Block

message_index: 1
custom_condition_count: 1
custom_value_1: ensembleMemberNumber
custom_operator_1: =
custom_value_1: 2
extract_data: on
parameter_count: 1
parameter_1: pressureReducedToMeanSeaLevel
extract_mode: all

Image Added

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Key

Filter by keys from header section

Filter by message index

Filter by message index list

Filter by date and time

Filter by single date and time

Filter by time only

Filter by time window

Filter by period

Filter by area

Filter by identifier

Filter by WMO station

Filter by other identifiers

Filter by custom conditions

Filter by custom condition with value

Filter by custom condition with rank

Filter by custom condition with range

Filter by custom condition with excluded range

Filter by multiple custom conditions

Sample data for the examples

Extract a single parameter

Extract with a single coordinate condition

Extract multiple parameters

Extract with multiple (nested) coordinate conditions

Extract tropical cyclone tracks