Description of XML-format for transfer of point forecasts (nowcasts) in the Sochi region
File name
Point forecast XML-file name is formed as follows:
PROVIDER_YYYYZZDDHHMM_VERSION.xml,
where:
PROVIDER – abbreviation of data provider (e.g., «RHM» - Roshydromet, «EC» Environment Canada etc.);
YYYYZZDDHHMM – forecast initial date and time (UTC): YYYY - year; ZZ - month; DD day; HH - hour; MM – minutes;
VERSION - version specifier (optional part of the name).
File structure
Each message starts with declaration of XML version and document encoding:
<?xml version="1.0" encoding="UTF-8" ?>
It is followed by the root document element <message> indicating the beginning of the
information part of the message. This information part has the following structure:
<message>
<header> . . . . . . . . .
</header >
<initialTime . . . . . . . . . >
<location . . . . . . . . . . >
<forecastTime . . . . . . . . . . >
<result . . . . . . >. . . . . </result>
..........
<result . . . . . . >. . . . . </result>
</forecastTime >
..........
< forecastTime . . . . . . . . . . >
<result . . . . . . >. . . . . </result>
..........
<result . . . . . . >. . . . . </result>
</forecastTime >
</location >
..........
<location . . . . . . . . . . >
< forecastTime . . . . . . . . . >
<result . . . . . . >. . . . . </result>
..........
<result . . . . . . >. . . . . </result>
</forecastTime >
..........
</location >
</initialTime>
</message>
Here element header introduces the forecasting system. This element can contain the
following nested elements: SYSTEM – forecasting system name (compulsory); PROVIDER forecast provider; VER – version.
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Example:
<header>
<system> ABOM </system>
<provider > EC </provider>
</header> .
Element initialTime presents forecast initial date and time (UTC) in compliance with
ISO8601 standard requirements with indication of a time zone.
Example:
<initialTime ITIME="24-02-2012T07:40:03+00:00" >
.............................
</initialTime >.
Element location binds included information with a specific geographical location. For
forecast verification purposes that location is usually associated with some meteorological
station. Either station identifier or direct specification of location via its coordinates, altitude
and name is needed, but it is recommended to use these specifications in parallel.
Specifiers of element location:
ID - station identifier. This is a standard 5-digit meteorological station index, if it is
available. Otherwise, this is an internal numeric station identifier (takes values <1000) from
the project data base (List of internal identifiers is available in the attached .xls-file).
LON, LAT, Z, NAME – longitude, latitude (in degrees in the form of real values),
altitude above the sea level (integer [m]), site name.
Example:
<location ID="37100" LON="40.0486" LAT=" 43.6147" Z="180" NAME="Kepsha" >
...............
</location> .
Element forecastTime is an information carrier for a particular forecast time set by FTIME
specifier. FTIME must be written in the form of integer number with unit of its measurement
(«H» - hours, «M» - minutes, «S» - seconds) without a delimiter. Besides this it is recommended
to explicitly specify the corresponding forecast valid time. Optional specifier VTIME presents
the forecast validity date and time (UTC) in compliance with ISO8601 requirements with
indication of time zone.
Example:
<forecastTime FTIME="15H" VTIME ="24-02-2012T07:40:03+00:00">
..........
</forecastTime >
Forecast results are presented by the document element result. Each meteorological variable is
described by one or several specifiers of result element introduced in the Table 1. The basic
specifier VAR presents the name of meteorological parameter. Other specifiers are used when
there is a need to further detail the basic description of meteorological variable (e.g., to indicate
vertical level; precipitation phase; data processing procedure etc.). The list of parameters and
their specifiers in the Table 1 can be expanded.
Example: <result VAR="TA" > -2.7 </result>
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There are two kinds of transmitted meteorological variables – instantaneous values and values
associated with some time interval (for example, maximum temperature or wind gusts). The
interval variables are derived via some processing of the time series of predicted values within
the interval. To correctly interpret forecast of such a variable, the corresponding time slot must
be defined in the XML-file. It is implied that the end of this time slot is presented by the
specifier FTIME of the document element forecastTime.
For interval variables description of a meteorological variable is supplemented by the specifier
PROC of processing type (MIN, MAX or average value AVE; accumulated total for a fixed time
interval - SUM) and specifier T of the time interval. T is presented in integer form with indication
of measurement units (“M” – minutes, “H” - hours) without a delimiter.
For ensemble forecasts specifiers MEMBER or PRODUCT, THRESHOLD and, INDICATION
are used to describe the result value.
If some specifier is not needed, it can be omitted or its value can be replaced by the data absence
identifier «*».
XML-file is terminated by the closing tag </message>.
Example of XML-file:
<?xml version="1.0" encoding="utf-8" ?>
<message>
<header>
<system > COSMO2.2 </system >
<provider> RHM </provider>
</header>
<initialTime ITIME="24-02-2012T06:00:00+00:00">
<location ID="37100" LON="40.0486" LAT=" 43.6147" Z="180"
NAME="Kepsha">
<forecastTime FTIME="1H" ITIME="24-02-2012T07:00:00+00:00">
<result VAR="TA" PRODUCT="EnsMean" > 1.7 </result >
<result VAR="TA" PRODUCT="PROB" THRESHOLD="0.0" INDICATION="-1">
0.12 </result>
<result VAR="WS" PROC="MAX" T="1H" PRODUCT="PROB" THRESHOLD="7"
INDICATION="1" > 0.21 </result>
<result VAR="WS" PROC="AVE" T="1H" PRODUCT="EnsMean" > 3.4
</result>
<result VAR="WD" PROC="AVE" T="1H" PRODUCT="EnsMean"> 32
</result>
<result VAR="P" TYPE="L" PROC="SUM" T="1H" PRODUCT="EnsMean"> 3.2
</result>
<result VAR="PI" TYPE="L" PROC="MAX" T="1H" PRODUCT="EnsMean"> 5
</result>
</forecastTime >
</location >
</initialTime >
</message>
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Table 1
Parameter
WS
Meteorological
Possible
parameters and
specifiers
units
Wind Speed [m/s] PROC,
T
TYPE,
Z,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
Possible values of specifiers and comments
PROC – indicator of processing type for
forecast data sequence within a specified time
interval. Possible values of PROC:
INS (default) – instantaneous value, MIN –
minimal value, MAX – maximal value, AVE –
temporal average value for the period
presented by specifier T.
T – specifier of the time interval duration and
unit of its measurement («H» - hours, «M» minutes, «S» - seconds) without a delimiter.
Default value - T="0M" (instantaneous
value).
TYPE – specifier of wind speed component:
“0” (default) – for horizontal wind
component; “1” – for vertical wind
component (WS is positive for up-going wind
component).
Z – height above the ground and the unit of
its measurement («M» - meters, «C» centimetres) without a delimiter. For wind
speed the default value is Z=”10M”.
PRODUCT – specifier of forecast products:
«Raw» - direct model output without any
postprocessing (default);
«EnsMean» - ensemble mean for EPS output;
«Spread» - ensemble spread;
«Prob» - probability of exceeding a
prescribed threshold.
This list of products might be expanded in the
future.
THRESHOLD – threshold value for
probability.
INDICATION – integer flag taking one of the
two values: «-1» – means probability «below
the THRESHOLD»; «1» – means probability
«above the THRESHOLD».
MEMBER – ensemble member. Possible
values: 0 – for deterministic or control
forecasts (default); 1,2,3… - numbers of
individual ensemble members.
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WD
Wind Direction
[°]
TA
Air Temperature
[°C]
TD
Dew Point
Temperature [°C]
TS
Snow
Temperature [°C]
TG
Ground
Temperature [°C]
RH
Relative
Humidity [%]
P
Precipitation
[mm]
PROC, T, Z,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
PROC, T, Z,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
PROC,T, Z,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
Z, PROC, T,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
Z,
PROC,
T,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
PROC, T, Z,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
TYPE, PROC,
T, MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
Possible values of specifiers PROC, Z, T,
MEMBER, PRODUCT, THRESHOLD,
INDICATION – as for WS.
Possible values of specifiers PROC, T,
MEMBER, PRODUCT, THRESHOLD,
INDICATION – as for WS.
Z – height above the ground and the unit of
its measurement («M» - meters, «C» centimetres) without a delimiter. For TA the
default value is Z=”2M”.
Possible values of specifiers:
PROC, T, Z, MEMBER,
PRODUCT, THRESHOLD,
INDICATION – as for TA.
Z – height above the ground.
Possible values of specifier Z:
1) “S” – snow surface (default);
2) numerical value and the unit of its
measurement («C» - centimetres, «M» meters) without a delimiter
Possible values of specifiers PROC, T,
MEMBER,PRODUCT, THRESHOLD,
INDICATION – as for WS.
Z – depth below the ground surface.
Possible values of specifier Z:
1) “S” – ground surface (default);
2) numerical value and the unit of its
measurement («C» - centimetres, «M» meters) without a delimiter
Possible values of specifiers PROC, T,
MEMBER, PRODUCT, THRESHOLD,
INDICATION – as for WS.
Possible values of specifiers PROC, T, Z,
MEMBER,
PRODUCT, THRESHOLD,
INDICATION – as for TA.
TYPE – precipitation phase:
“L” – liquid precipitation;
“S” – solid precipitation;
“LS” – liquid and solid precipitation with
prevailing liquid phase;
“SL” – solid and liquid precipitation with
prevailing solid phase;
“F” – freezing precipitation;
“D” – drizzle.
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If TYPE is absent then P is interpreted as total
precipitation.
T – presents the accumulation period.
PROC – specifies the procedure for
calculation of precipitation totals. For
forecasts the only possible value of PROC is
SUM – precipitation total for a fixed period
(default for forecasts of parameter P).
PI
AP
Precipitation
Intensity [mm/h]
Atmospheric
Pressure [hPa]
V
Visibility [m]
HS
Snow Depth [cm]
NS
New Snow [cm]
HC
Cloud Base
Height [m]
TYPE, PROC,
T, MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
Z,
PROC, T,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
PROC, T,
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
T, MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
PROC,
T,
Z, MEMBER,
PRODUCT,
THRESHOLD,
INDICATION
Possible values of specifiers MEMBER,
PRODUCT, THRESHOLD, INDICATION –
as for WS.
TYPE – precipitation phase:
“L” – liquid precipitation;
“S” – solid precipitation;
“LS” – liquid and solid precipitation with
prevailing liquid phase; “SL” – solid and
liquid precipitation with prevailing solid
phase;
“F” – freezing precipitation.
PROC, T, MEMBER,PRODUCT,
THRESHOLD, INDICATION – as for WS.
Z – altitude:
“MSL” - at Mean Sea Level,
“STN” – at station level
Possible values of specifier PROC, T,
MEMBER, PRODUCT, THRESHOLD,
INDICATION – as for WS.
Possible values of specifiers PROC, T,
MEMBER, PRODUCT, THRESHOLD,
INDICATION – as for WS.
Possible values of specifiers MEMBER,
PRODUCT, THRESHOLD, INDICATION –
as for WS.
Possible values of specifiers T, MEMBER,
PRODUCT, THRESHOLD, INDICATION –
as for WS.
PROC, T, MEMBER, PRODUCT,
THRESHOLD, INDICATION – as for WS.
Z – specifier of cloud base height reference
level: “MSL” – Mean Sea Level;
“STN” – station level (default).
……
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