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These examples show how to extract data in a table format from BUFR files.

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.

The data used for the examples

This is a summary of the data files used for the examples:

File	Structure	Description
temp.bufr		Classic radiosonde data. One message contains a vertical profile for one station with various parameters (e.g. temperature, wind etc.) on a set of pressure levels.

Extracting a single parameter

Example

Filter

Results

Comments

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

extract_data: on
parameter_1: airTemperature

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)

extract_data: on
parameter_1: airTemperature
parameter_rank_1: 1

Here we explicitly asked for the first temperature value. It has 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

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

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

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

For station 78016: extract all the temperature values

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

Extracting with a single coordinate condition

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

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

Here we explicitly say the we only want the matching temperature values which appear inside a pressure block (in these messages this is always the case). By using the coordinate condition pressure will be extracted as well 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

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

Here we further refined the coordinate condition.

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

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

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

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

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

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

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

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

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

Extracting multiple parameters

Example Filter Results Comments

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

extract_data: on
parameter_1: windDirection
parameter_2: windSpeed

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.

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

extract_data: on
parameter_1: windDirection
parameter_2: windSpeed
coordinate_condition_count: 1
coordinate_1: pressure

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

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

Multiple (nested) coordinate conditions

Task

Filter

Results

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

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

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

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