Carbon LAS -- visualizing pCO2 anomaly (difference from Takahashi gridded)

karlmsmith commented 6 years ago

Reported by steven.c.hankin on 18 Jan 2008 01:21 UTC With the carbon LAS we can visualize the value of pCO2 along track lines. Chris Sabine has asked to be able to visualize the difference between these values and the gridded monthly field that Takahashi computed. This is not a request for a general solution to differencing. Rather it is a very specific pre-defined calculation.

I suspect that it can be handled in a quite simple manner through what we used to call a "custom init script". (What is the name given to the equivalent extensibility mechanism now?) As follows:

Add a new variable into the LAS XML -- say, "pCO2_anomaly"

In the Velocity template for the carbon server, any time that pCO2_anomaly has been requested, make sure that we request pCO2_SW

In the Ferret "init" process, anytime that pCO2_anomaly has been requested 1) USE the Takahashi gridded monthly netCDF dataset

2) with LET commands define pCO2_anomaly -- the SAMPLEXYT (see note) function can get the values of the gridded data interpolated to the lat-long-climTime positions of the data -- then take the difference.

note: if a SAMPLEXYT function does not exist, then do all of the above with SAMPLEXY and the annual Takahashi climatology and add a SAMPLEXYT function as a trac ticket.

Migrated-From: http://dunkel.pmel.noaa.gov/trac/las/ticket/359

karlmsmith commented 6 years ago

Attachment from steven.c.hankin on 5 Feb 2008 00:53 UTC Data report for 2008 dataset NDP-088_ed.docx

karlmsmith commented 6 years ago

Attachment from steven.c.hankin on 5 Feb 2008 00:54 UTC Computing the climatologoical mean -- 2008 GlobOcnPCO2Text_082407.docx

karlmsmith commented 6 years ago

Attachment from steven.c.hankin on 5 Feb 2008 00:56 UTC Reference data - microAtm per year GlobOcnPCO2Tables_030607.docx

karlmsmith commented 6 years ago

Attachment from steven.c.hankin on 5 Feb 2008 00:57 UTC Figure showing global density of carbon observations GlobOcnPCO2AllFigs_030607.pdf

karlmsmith commented 6 years ago

Comment by jonathan.s.callahan on 29 Jan 2008 19:52 UTC The Takahashi gridded dataset is available here:

http://ferret.pmel.noaa.gov/thredds/dodsC/data/PMEL/Takahashi.nc

But there is one basic problem with generating a comparison:

The Takahashi gridded dataset contains air-sea fluxes (with or without various corrections) and not the actual measurements of pCO2_atm and pCO2_sw.

The Takahashi database of in-situ measurements contains only the following pCO2 variables:

pCO2_sw (partial pressure of CO2 in seawater)
pCO2_eq (partial pressure of CO2 in the equilibrator)

To compare these two datasets we would need either pCO2_atm in the in-situ database or pCO2_atm and pCO2_sw in the gridded dataset. Neither is available to my knowledge.

I cannot see any way around this.

karlmsmith commented 6 years ago

Comment by @AnsleyManke on 29 Jan 2008 20:00 UTC I've taken a stab at this and checked in the resulting changes to the OCDMS project under its CUSTOMIZATION. As a placeholder, I have used the variable PCO2_FULL from the gridded dataset. WHICH is the correct one to use? The variables in the gridded dataset are:

    2> http://ferret.pmel.noaa.gov/thredds/dodsC/data/PMEL/Takahashi.nc
 name     title                             I         J         K         L
 FLUX     carbon flux                      1:72   1:45   ...    1:1
 PCO2_FULL
          pCO2 air-sea w/ full correction  1:72   1:45   ...    1:12
 PCO2_HALF
          pCO2 air-sea w/ half correction  1:72   1:45   ...    1:12
 PCO2_DIFF
          pCO2_full - pCO2_half            1:72   1:45   ...    1:12

Script changes are

'''Jons_initialize_data_insitu.jnl''' Allow for an init script to be run if there is one defined.

*''' OCDMS_title.jnl''' Add the anomoly info to the title.

'''Jons_XY_overlay_basemap.jnl''' Add SET DATA/SAVE; SET DATA/RESTORE as we now have two datasets open and current dataset needs to be preserved.
'''OCDMS.vm, OCDMS_cruise_summary.vm, OCMS_table_of_cruises.vm''' In all of these, add the following hack: if the variable chosen is the pCO2_anomaly then reset the variable to pco2_sw.:

## Hack to allow anomoly from gridded data.
#if ($var == "pCO2_anomaly")
   #set ($var = "pCO2_sw")
#end

karlmsmith commented 6 years ago

Comment by jonathan.s.callahan on 29 Jan 2008 20:06 UTC '''We may be in luck!''' It seems the necessary data is available here:

http://islscp2.sesda.com/ISLSCP2_1/data/carbon/air_sea_gas_exchange_xdeg/

karlmsmith commented 6 years ago

Comment by @AnsleyManke on 30 Jan 2008 18:02 UTC Chris Sabine points to this dataset we should be using:

http://www.ldeo.columbia.edu/res/pi/CO2/carbondioxide/air_sea_flux/pco2_940.txt

(this is the same as the air_sea_data_5d file from the islscp2 link in the above comment)

karlmsmith commented 6 years ago

Comment by steven.c.hankin on 4 Feb 2008 22:30 UTC Just spoke to Chris Sabine about this and realize that we need to be very careful in our terminology and our house-keeping, or we will end up mixing apples and oranges. Not only are there multiple versions of the raw data, there are also multiple versions of the climatologies.

Here are the handles by which we can refer to the versions

'Old' version:

data collection has 940K measurements
climatology is referenced to 1995
publication was in 2002

'New' version

data collection has 2.79M measurements
climatology is referenced to 2000
publication is in 2008 (still in press, so you may hear 2007)

What it means to be 'refenced to year XXX' is the subtraction of 1.5 microAtmospheres/year (to the closest month). i.e. comparing Jan, 2000 to Jan 1998 would be a correction of 2 * 1.5 microAtm.

To get the sign of the correction and all the other background go to the Takahashi publication of the year indicated.

There is an actual field of pCO2 in sea water available. To get it we need to ask Alex, who in turn will probably ask Taro. To get from pCO2 of sea water to delta pCO2 need to substract out the estimated pCO2 of air, which is a computed as a constant with both a latitude and time of year )month) correction.

We need to contact Alex and get the pCO2_SW climatology field.

Note that Chris believes there are no longer the 'half' and 'full' correction fields on the 2008 version of the climatologies. Is it possible that our LAS server has the 2008 data but still the 2002 climatologies?

karlmsmith commented 6 years ago

Modified by @AnsleyManke on 7 Feb 2008 21:32 UTC

karlmsmith commented 6 years ago

Modified by steven.c.hankin on 7 Feb 2008 21:48 UTC

karlmsmith commented 6 years ago

Comment by steven.c.hankin on 8 Feb 2008 16:16 UTC We believe that the gridded field that Jon has pointed to at http://ferret.pmel.noaa.gov/thredds/dodsC/data/PMEL/Takahashi.nc is from the 2002 Takahashi data. We need to get the 2008 gridded data.

Ansley has agreed to pick this up and reformat it to netCDF (Ansley, please put "2008" or "based upon 2.79M measurements" into the dataset title). Jon can help you locate the file(s). Please let me know what variables the gridded fields contain, so that I can (if necessary) contact Taro about getting the pCO2_SW gridded climatology.

karlmsmith commented 6 years ago

Modified by @AnsleyManke on 5 Jan 2011 23:03 UTC

NOAA-PMEL / LAS

Carbon LAS -- visualizing pCO2 anomaly (difference from Takahashi gridded) #365