{"id":5617,"date":"2018-07-06T04:08:18","date_gmt":"2018-07-06T02:08:18","guid":{"rendered":"http:\/\/www.sigterritoires.fr\/?p=5617"},"modified":"2023-04-28T14:58:03","modified_gmt":"2023-04-28T12:58:03","slug":"how-to-integrate-free-marine-and-terrestrial-weather-forecasts-into-qgis-2","status":"publish","type":"post","link":"https:\/\/www.sigterritoires.fr\/index.php\/en\/how-to-integrate-free-marine-and-terrestrial-weather-forecasts-into-qgis-2\/","title":{"rendered":"How to integrate free marine and terrestrial weather forecasts into QGis"},"content":{"rendered":"

In the previous article we discussed how\u00a0\u00a0\u00a0How to integrate free marine and terrestrial weather forecasts into\u00a0ArcGis<\/a>\u00a0.
\nIn this article we will discuss how to integrate these data into a\u00a0QGis\u00a0project\u00a0.\u00a0We will use 8- day marine forecast data.\u00a0These data is provided by the companies\u00a0\u00a0\u00a0 NASCA<\/a>\u00a0\u00a0\u00a0and\u00a0\u00a0\u00a0 ACTIMAR<\/a>\u00a0, via their \u00a0products\u00a0\u00a0enav-forecast\u00a0.\u00a0In addition to the software that uses these forecasts and allows for their consultation and analysis (\u00a0 enav-viewer<\/a>\u00a0,\u00a0\u00a0\u00a0enav-forecast\u00a0,\u00a0\u00a0\u00a0enav-forecast\u00a0for iPhone\u00a0,\u00a0\u00a0\u00a0enav\u00a0-Pilot\u00a0), these companies also provide access to data via a WFS connection.<\/p>\n

What data is available?<\/strong><\/p>\n

Regarding the data type, you access the 8-\u00a0day\u00a0forecasts,\u00a0every 3 hours, for the following parameters:<\/p>\n

\n
height (in m)\u00a0, direction\u00a0(in \u00b0) and wave period (in s)<\/li>\n
crossed sea (wave direction in \u00b0\u00a0, direction\u00a0of the swell in \u00b0)<\/li>\n
speed (in\u00a0knots\u00a0) and direction (in \u00b0) of the average wind<\/li>\n
speed (in\u00a0knots\u00a0) of wind gusts<\/li>\n
speed (in knots\u00a0) and direction (in \u00b0) of the surface current<\/li>\n
temperature (in \u00b0 C) of the sea surface<\/li>\n
temperature (in \u00b0 C) of the air<\/li>\n

rainfall (in mm)<\/li>\n<\/ul>\n
What data mesh?<\/strong><\/p>\n
The mesh of free forecasts is 0.5 \u00b0.\u00a0Other meshes are available but subject to subscription (see subscriptions).
\nThe forecasts cover the whole world.<\/p>\n
Frequency of update<\/strong><\/p>\n
The forecasts are updated four times a day.<\/p>\n
Establish the WFS connection<\/strong><\/p>\n
To establish a WFS connection click \u00a0the button \u201cAdd a WFS layer\u201d, then click \u00a0the button \u201cNew\u201d\u00a0to create the connection parameters.<\/p>\n
$\"\"$ <\/p>\n
As for the name type a rather specific name: NASCA Marine Weather, for example.
\nFor the URL, enter the following string:
\nClick OK to close the configuration.
\nThe connection now appears in the list of available connections.<\/p>\n
Before you log in<\/strong><\/p>\n
Open a project with the WGS84 Geographic SCR.\u00a0Display a base map that allows you to zoom in on the area of \u200b\u200binterest.\u00a0When you connect to the WFS server,\u00a0QGis\u00a0will send a query with the coordinates of the four corners of your current display.\u00a0The server will send the predictions found inside this rectangle to your machine.<\/p>\n
If you are in projection<\/a> mode and not in geographical, neither\u00a0QGis\u00a0nor the server will make a transformation of\u00a0the coordinates. Frequently, you\u00a0will have no result in return not even an error message.<\/p>\n
Therefore it has to be verified that what you are going to transmit are coordinates in degrees of latitude and longitude.\u00a0For that, simply, look at the status bar at the bottom of the QGis window: you have a field called \u201ccontact information\u00a0\u00ab\u00a0.\u00a0The values \u200b\u200bin this field must be between -180 and 180. If this is the case, you are working with geographic coordinates.<\/p>\n
If you are in geographical coordinates but do not zoom in on the area of \u200b\u200binterest, you may have an area too big for the query.\u00a0In addition to being time consuming, WFS servers still have a limit on the number of records.\u00a0If it is reached, the server sends the found records and then suddenly stops.\u00a0You will not have a warning message; and the data will be cut down.<\/p>\n
How to connect to the WFS server<\/strong><\/p>\n
A new connection now appears in the list of proposed connections when you click the button \u00ab\u00a0Add a WFS layer\u00a0\u00bb.\u00a0Click the \u201cLog in\u00a0\u00bb.<\/p>\n
$\"\"$ <\/p>\n
You will only use the layer: view_meteo99<\/p>\n
Click this line to select it.\u00a0Uncheck the box\u00a0\u00a0\u00a0\u201cCache\u00a0feature\u201d.
\nClick \u00ab\u00a0Add\u00a0\u00bb.<\/p>\n
Displaying the forecast data<\/strong><\/p>\n
After a few seconds, the new layer is added to the\u00a0QGis\u00a0map window.<\/p>\n
$\"\"$ <\/p>\n
Each forecast \u201cpoint\u201d\u00a0is, actually, a collection of 66 points.\u00a0To be able to view the forecasts for a given time, you will have to make a selection of the data set of each point.\u00a0Performing this task as requests to the server is too complicated and it is not worth.\u00a0The most efficient method is to display all the data in\u00a0QGis\u00a0and create a new layer on your workstation.<\/p>\n
You can do this directly by clicking the legend of the layer and selecting \u00ab\u00a0Save as …\u201d\u00a0But do not rush, there are other little things to fix, and we’ll do it all at once.<\/p>\n
WFS connections with\u00a0QGis\u00a0have a small flaw: according to the first value found for an attribute field of the\u00a0table,\u00a0it defines the data type.\u00a0Often we are left with numeric fields in the original table of the server which are interpreted as text strings by\u00a0QGis\u00a0, locally.\u00a0With marine forecasts, the \u00a0problem does not arise for the force and speed values, which are always\u00a0\u00a0values \u200b\u200bto the decimal point.\u00a0On the other hand, for direction values, which are integers, the problem arises.
\nYou will have direction values \u200b\u200bas a\u00a0text\u00a0string.\u00a0Even if, for a simple display it does not change much, when displaying oriented arrows (currents, waves, wind) it is impossible to request a rotation of the symbol with a text field .\u00a0It is imperative that the direction field be numeric.<\/p>\n
To solve this problem, you must create a new numeric field and use the field calculator to calculate the text strings values \u200b\u200b for the three direction fields (wave, wind, current).<\/p>\n
Tedious work.\u00a0So, we have to find a less tedious solution.\u00a0We have built a treatment model with the QGis \u201cGraphic modeller\u201d.\u00a0This is a small file, which you can download in\u00a0\u00a0\u00a0here<\/a>\u00a0.<\/p>\n
Unzip the file into a directory of your choice.<\/p>\n
Open the Chart Modeller:<\/p>\n
$\"\"$ <\/p>\n
In the Modeller window, click the first button to open the downloaded template.\u00a0Point to the\u00a0meteoNasca.model\u00a0file.
\nThe model is loading.<\/p>\n
$\"\"$ <\/p>\n
To execute it, click the right button\u00a0 \u201cLaunch the model\u00a0\u00bb.<\/p>\n
$\"\"$ <\/p>\n
Check that the input file is the layer \u00ab\u00a0view_meteo99\u00a0\u00bb.
\nBrowse the directories to define the location and name of the\u00a0shape\u00a0file\u00a0that will be created on your\u00a0computer. Select\u00a0\u00ab\u00a0Save to file\u00a0\u00bb
\nClick on\u00a0Run
\nThe new layer is loaded in the map window.\u00a0You can now delete the WFS layer, it avoids having to load each time you\u00a0change\u00a0the grip of the view.<\/p>\n
$\"\"$ <\/p>\n
Symbology<\/strong>\u00a0of the forecast data<\/strong><\/p>\n
For simple data (temperature, rainfall …) the only thing to remember is that you have 66 points superimposed on each forecast location.\u00a0You must go through a \u00ab\u00a0subset query\u00a0\u201c\u00a0\u00a0so as to show only one step at a time\u00a0:
\nLayer properties -> \u00a0\u00bb\u00a0\u00a0\u00a0General\u00a0\u00a0\u00a0\u00bb-> Subset (click on query builder)<\/p>\n
$\"\"$ <\/p>\n
You have two attributes, the first for today’s date, and the second for the hour.\u00a0\u00a0<\/strong>\u00a0WARNING!<\/strong>\u00a0The hour is GMT not in local hour.<\/strong><\/p>\n
Before applying the\u00a0symbologies, do not forget to define the selection request.\u00a0Otherwise you will end up with a stack of symbols on each point.<\/p>\n
For complex data (wind, waves, current) you have at least two associated values: direction and strength.\u00a0The classic way to display this type of data is to use an arrow oriented in the direction of the phenomenon and to assign it either a size or a different colour depending on the force.<\/p>\n
First thing to know: How is the direction of the phenomenon coded?
\nAll directions present in the attributes of the table indicate the direction from which the phenomenon originates (the direction from which it comes).
\nTo orient the arrows, it is necessary to apply a rotation to the symbol.\u00a0If you choose a symbol \u201carrow up\u201d\u00a0\u00a0and you enter as rotation field, only, the name of the direction field, your arrows will indicate the opposite direction!\u00a0In this case, use an expression, for rotation, of type [field direction] – 180.<\/p>\n
We have prepared three layer files with\u00a0standard\u00a0symbology\u00a0that should do the trick.\u00a0You can download them in\u00a0\u00a0\u00a0here<\/a>\u00a0.
\nIn the compressed file, you have three\u00a0Qgis\u00a0layers style\u00a0files\u00a0(wind, current and waves) and a folder with the symbols used for the wind on the weather charts (barbules).
\nThe first three can be extracted in the directory of your choice.\u00a0On the other hand, the file\u00a0\u00a0\u00a0\u201cbarbs\u201d\u00a0\u00a0\u00a0must be copied in the Gis\u00a0\/\u00a0apps\u00a0\/\u00a0qgis\u00a0\/\u00a0svg installation directory\u00a0.\u00a0If not, the symbols will not be accessible for style files.<\/p>\n
The\u00a0symbology\u00a0for the wind is as follows:<\/p>\n
$\"\"$ <\/p>\n
The symbols used are standard barbules, with increments of 5 in 5 knots up to 65 knots.
\nThe rotation field is already corrected to have the right orientation of the barbules.<\/p>\n
The\u00a0symbology\u00a0for the current is as follows:<\/p>\n
$\"\"$ <\/p>\n
The symbols used are\u00a0arrows,\u00a0with increments of 1 knot.\u00a0The size of the arrows increases according to the speed.\u00a0Up to 3 knots are in blue, between 3 and 5 are in orange and from 6 knots in red.
\nThe rotation field is corrected by 180 \u00b0 to obtain the right orientation of the arrows.
\nRemember to add in the selection request, besides date and time, a filter on the direction and speed so as not to display the null values \u200b\u200bon the ground (\u00a0CourantVal<\/strong>\u00a0<> 0 ANDICurDir<\/strong>\u00a0<> 0<\/strong>\u00a0).<\/p>\n
The\u00a0symbology\u00a0for the waves is as follows:<\/p>\n
$\"\"$
\nThe symbols used are\u00a0arrows,\u00a0with increments of 1 meter.\u00a0Heights of up to 3 meters are green, between 4 and 7 are yellow and from 7 knots are orange-red.
\nThe rotation field is corrected by 180 \u00b0 to have the right orientation of the arrows.
\nRemember to add in the selection request, besides the date and time, a filter on the direction and speed so as not to display the null values \u200b\u200bon the ground (\u00a0HsVal<\/strong>\u00a0<> 0 AND<\/strong>\u00a0IHsDir<\/strong>\u00a0<> 0<\/strong>).
\nThe labels indicate the significant height of the waves in meters, and the wave period in seconds.<\/p>\n
If you have questions, feel free to leave a comment!<\/p>\n","protected":false},"excerpt":{"rendered":"
In the previous article we discussed how\u00a0\u00a0\u00a0How to integrate free marine and terrestrial weather forecasts into\u00a0ArcGis\u00a0. In this article we will discuss how to integrate these data into a\u00a0QGis\u00a0project\u00a0.\u00a0We will use 8- day marine forecast data.\u00a0These…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"give_campaign_id":0,"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"sfsi_plus_gutenberg_text_before_share":"","sfsi_plus_gutenberg_show_text_before_share":"","sfsi_plus_gutenberg_icon_type":"","sfsi_plus_gutenberg_icon_alignemt":"","sfsi_plus_gutenburg_max_per_row":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1260],"tags":[],"class_list":["post-5617","post","type-post","status-publish","format-standard","hentry","category-non-classe-en"],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p6XU0A-1sB","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/5617","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/comments?post=5617"}],"version-history":[{"count":0,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/5617\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/media?parent=5617"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/categories?post=5617"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/tags?post=5617"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}