Vertical Coordinates - Revision history

H.wolff: Change Raijin -> Gadi

2021-08-31T23:27:04Z

Change Raijin -> Gadi

S.wales at 00:52, 14 June 2019

2019-06-14T00:52:47Z

S.wales at 00:47, 14 June 2019

2019-06-14T00:47:52Z

S.wales at 00:27, 14 June 2019

2019-06-14T00:27:02Z

S.wales at 00:23, 14 June 2019

2019-06-14T00:23:55Z

S.wales: Created page with "Climate models use a variety of vertical coordinate systems, here are the values for the models commonly in use in the Centre == UM Vertical Coordinates == The UM uses a hyb..."

2019-06-14T00:15:20Z

Created page with "Climate models use a variety of vertical coordinate systems, here are the values for the models commonly in use in the Centre == UM Vertical Coordinates == The UM uses a hyb..."

New page

Climate models use a variety of vertical coordinate systems, here are the values for the models commonly in use in the Centre

== UM Vertical Coordinates ==

The UM uses a hybrid height coordinate system, it is terrain following up to a specified height, above which it is regular height levels.

The [[Analysing_UM_outputs#Iris|Iris]] library can automatically work out altitude values from a UM file, provided it has access to orography.

The full definition of UM height levels can be found in Appendix A of [https://code.metoffice.gov.uk/doc/um/latest/papers/umdp_F03.pdf UMDB F03]

<pre>
Z(i, j, k) = Zsea(k) + C(k) + orography(i, j)
Zsea(k) = eta(k) * top_level_height
C(k) = (1 - eta(k) / eta(first_constant_r_rho_level))**2 # for k <= first_constant_r_rho_level
= 0 # for k > first_constant_r_rho_level
</pre>

The values of <code>eta(k)</code>, <code>top_level_height</code> and <code>first_constant_rho_level</code> can be found in the UM vertical coordinate namelist, standard namelists are found on Raijin under <code>/projects/access/umdir/vn${VN}/ctldata/vert/</code>. There are separate <code>eta</code> values for variables defined on theta or rho levels.

== WRF Vertical Coordinates ==

WRF uses a hybrid pressure coordinate system

@@ Line 16: / Line 16: @@
 </pre>
-The values of <code>eta(k)</code>, <code>top_level_height</code> and <code>first_constant_rho_level</code> can be found in the UM vertical coordinate namelist, standard namelists are found on Raijin under <code>/projects/access/umdir/vn${VN}/ctldata/vert/</code>. There are separate <code>eta</code> values for variables defined on theta or rho levels.
+The values of <code>eta(k)</code>, <code>top_level_height</code> and <code>first_constant_rho_level</code> can be found in the UM vertical coordinate namelist, standard namelists are found on Gadi under <code>~access/umdir/vn${VN}/ctldata/vert/</code>. There are separate <code>eta</code> values for variables defined on theta or rho levels.
 The values of Zsea and C are also available in the LOOKUP header of UM output files, as values <code>blev</code> and <code>bhlev</code> respectively. These header values can be accessed using [[Analysing_UM_outputs#Mule|Mule]]

← Older revision		Revision as of 00:27, 14 June 2019
Line 26:		Line 26:
	</pre>		</pre>
	with <code>Ph</code> the hydrostatic pressure, and <code>Pht</code> and <code>Phs</code> the values at the topmost and surface levels respectively		with <code>Ph</code> the hydrostatic pressure, and <code>Pht</code> and <code>Phs</code> the values at the topmost and surface levels respectively
		+
		+	[[Category:WRF]][[Category:Unified Model]]

← Older revision		Revision as of 00:23, 14 June 2019
Line 21:		Line 21:

	WRF uses a hybrid pressure coordinate system		WRF uses a hybrid pressure coordinate system
		+
		+	<pre>
		+	eta = (Ph - Pht)/(Phs - Pht)
		+	</pre>
		+	with <code>Ph</code> the hydrostatic pressure, and <code>Pht</code> and <code>Phs</code> the values at the topmost and surface levels respectively

@@ Line 10: / Line 10: @@
 <pre>
-Z(i, j, k) = Zsea(k) + C(k) + orography(i, j)
+Z(i, j, k) = Zsea(k) + C(k) * orography(i, j)
 Zsea(k) = eta(k) * top_level_height
 C(k) = (1 - eta(k) / eta(first_constant_r_rho_level))**2 # for k <= first_constant_r_rho_level
@@ Line 17: / Line 17: @@
 The values of <code>eta(k)</code>, <code>top_level_height</code> and <code>first_constant_rho_level</code> can be found in the UM vertical coordinate namelist, standard namelists are found on Raijin under <code>/projects/access/umdir/vn${VN}/ctldata/vert/</code>. There are separate <code>eta</code> values for variables defined on theta or rho levels.
 == WRF Vertical Coordinates ==

@@ Line 7: / Line 7: @@
 The [[Analysing_UM_outputs#Iris|Iris]] library can automatically work out altitude values from a UM file, provided it has access to orography.
-The full definition of UM height levels can be found in Appendix A of [https://code.metoffice.gov.uk/doc/um/latest/papers/umdp_F03.pdf UMDB F03]
+The full definition of UM height levels can be found in Appendix A of [https://code.metoffice.gov.uk/doc/um/latest/papers/umdp_F03.pdf UMDP F03]
 <pre>