Basal melt in AQ. Closes #14

Author: mankoff

README.org

@@ -105,69 +105,47 @@ r.colors map=basins,basins_grow color=viridis
 
 *** Antarctica
 
-+ 65 Gt/yr from Pattyn (2010) http://doi.org/10.1016/j.epsl.2010.04.025
-+ If split by area, its 25 % vs 75 %
-+ Better: Split by weighted geothermal heat for E v W Antarctica
-  + This is still (somewhat) weighted by area. Neglects 0 basal melt in areas when ice sheet is frozen to the bed. Neglects frictional heating differences between E & W.
+Van Liefferinge (2013) http://doi.org/10.5194/cp-9-2335-2013 
 
-**** Geothermal heat
+Convert MAT file to XYZ for importing into GRASS
 
-Load 
-#+BEGIN_SRC bash :exports both :results verbatim
-grass -c ./G_AQ/Shapiro_2004
-
-fname=Shapiro_2004/Antarctica_heat_flux_5km.nc
-r.in.gdal -o input=NetCDF:${DATADIR}/${fname}:bheatflx output=bheatflux
-g.region raster=bheatflux -pa
-#+END_SRC
-
-Sum by ROI. Units doesn't matter here, we just want relative %
-#+BEGIN_SRC bash :exports both :results verbatim
-r.mask raster=basins@PERMANENT --o --q
-r.univar -g bheatflux | grep ^sum=
-eval $(!!)
-gf_all=${sum}
-
-r.mask raster=basins@PERMANENT maskcats=1 --o --q
-eval $(r.univar -g bheatflux | grep ^sum=)
-gf_e=${sum}
-
-r.mask raster=basins@PERMANENT maskcats=2 --o --q
-eval $(r.univar -g bheatflux | grep ^sum=)
-gf_w=${sum}
-
-r.mask raster=basins@PERMANENT maskcats=3 --o --q
-eval $(r.univar -g bheatflux | grep ^sum=)
-gf_p=${sum}
+#+BEGIN_SRC jupyter-python :exports both
+import scipy as sp
+import numpy as np
+import pandas as pd
 
-r.mask -r
-#+END_SRC
+mat = sp.io.loadmat('/home/kdm/data/Van_Liefferinge_2023/Melt_Mean_Std_15exp.mat')
+X = mat['X'].flatten() * 1E3 # convert from km to m
+Y = mat['Y'].flatten() * 1E3
+m = mat['MeanMelt'].flatten() / 10 # cm to mm
 
-#+BEGIN_SRC bash :exports both :results verbatim
-echo East
-echo "${gf_e}/${gf_all}"|bc -l
-echo West
-echo "${gf_w}/${gf_all}"|bc -l
-echo Peninsula
-echo "${gf_p}/${gf_all}"|bc -l
+melt = pd.DataFrame(np.array([X,Y,m]).T, columns=['x','y','melt'])\
+         .dropna()
+melt.to_csv('./tmp/melt.csv', header=False, index=False)
+melt.head()
 #+END_SRC
 
 #+RESULTS:
-: East
-: .70880323929018432555
-: West
-: .25048300096071189826
-: Peninsula
-: .04071375974910620730
-
-Results:
-
-+ All: 65 Gt/yr Pattyn (2010) http://doi.org/10.1016/j.epsl.2010.04.025
-+ East: 65 * 0.71 = 46.15
-+ West: 65 * 0.25 = 16.25
-+ Peninsula: 65 * 0.04 = 2.6
+|        |         x |          y |        melt |
+|--------+-----------+------------+-------------|
+| 148741 | 1.045e+06 | -2.14e+06  | 1e-09       |
+| 149859 | 1.03e+06  | -2.135e+06 | 0.00146608  |
+| 149860 | 1.035e+06 | -2.135e+06 | 0.000266042 |
+| 149861 | 1.04e+06  | -2.135e+06 | 1e-09       |
+| 149862 | 1.045e+06 | -2.135e+06 | 0.00045698  |
 
+#+BEGIN_SRC bash :exports both :results verbatim
+grass ./G_AQ/PERMANENT
+g.mapset -c liefferinge_2023
+r.in.xyz input=./tmp/melt.csv output=melt sep=, --o
+r.univar -g map=melt | grep sum
+r.univar -g map=melt zones=basins |grep sum
+#+END_SRC
 
+sum=69.3982306335468
+sum=46.7540492694752
+sum=18.8528624157926
+sum=3.18704264192471
 
 ** Antarctic Ice shelves
 

dat/aq_baseline.csv

@@ -15,4 +15,4 @@ DYN,Dynamics,1840+430,davison_2023
 ICE,Icebergs,1840,davison_2023
 SUB,Submarine melt,430,davison_2023
 EV,Evaporation,10,TODO
-BM,Basal melt,65,pattyn_2010
+BM,Basal melt,70,van-liefferinge_2013

dat/aq_east.csv

@@ -15,4 +15,4 @@ DYN,Dynamics,910+90,davison_2023
 ICE,Icebergs,910,davison_2023
 SUB,Submarine melt,90,davison_2023
 EV,Evaporation,10,
-BM,Basal melt,46,pattyn_2010 weighted by shapiro_2004 geothermal
+BM,Basal melt,47,van-liefferinge_2013

dat/aq_peninsula.csv

@@ -15,4 +15,4 @@ DYN,Dynamics,160+80,davison_2023
 ICE,Icebergs,160,davison_2023
 SUB,Submarine melt,80,davison_2023
 EV,Evaporation,3,TODO
-BM,Basal melt,3,pattyn_2010 weighted by shapiro_2004 geothermal
+BM,Basal melt,3,van-liefferinge_2013

dat/aq_west.csv

@@ -15,4 +15,4 @@ DYN,Dynamics,770+260,davison_2023
 ICE,Icebergs,770,davison_2023
 SUB,Submarine melt,260,davison_2023
 EV,Evaporation,3,
-BM,Basal melt,16,pattyn_2010 weighted by shapiro_2004 geothermal
+BM,Basal melt,19,van-liefferinge_2013

library.bib

@@ -363,3 +363,18 @@ @article{shapiro_2004
   volume    = {223},
   year	    = {2004}}
 
+@article{van-liefferinge_2013,
+  author    = {Van Liefferinge, B. and Pattyn, F.},
+  title     = {Using ice-flow models to evaluate potential sites of million year-old ice in
+                  {A}ntarctica},
+  journal   = {Climate of the Past},
+  year 	    = 2013,
+  volume    = 9,
+  number    = 5,
+  pages     = {2335–2345},
+  month     = 10,
+  ISSN 	    = {1814-9332},
+  url 	    = {http://dx.doi.org/10.5194/cp-9-2335-2013},
+  DOI 	    = {10.5194/cp-9-2335-2013},
+  file	    = {./v/van liefferinge/van-liefferinge_2013.pdf},
+  publisher = {Copernicus GmbH}}

ms.tex

@@ -93,8 +93,6 @@ \section{Methods}
 
 In Antarctica, we use the MEaSUREs Antarctic Boundaries for IPY 2007-2009 from Satellite Radar, Version 2 (NSIDC product 0709; \citet{mouginot_2017,rignot_2013}) to separate Antarctica into East, West, and Peninsula. We drop all unattached islands, so the sum of the regional terms may not equal the total Antarctic values in Fig. \ref{fig}.
 
-Most existing estimates are provided with enough geospatial metadata that we simply assign flow estimates to the appropriate region. However, we do not have access to the basal mass balance for Antarctica in spatial map form, only a total Antarctic-wide value from \citet{pattyn_2010} reported at 65 Gt yr$^{-1}$. To estimate basal melt for East and West Antarctica, we scale by the magnitude of geothermal heat flux (from \citet{shapiro_2004}) scaled by area for East, West, and Peninsula which is 70 \%, 25 \%, and 5 \% respectively. This is slightly better than scaling by area alone which has 75 \% of the area in East Antarctica. This method neglects the contribution of shear heating (ice velocity) when partitioning basal melt.
-
 \section{Missing terms and limitations}
 \label{sec:limits}
 
@@ -204,8 +202,7 @@ \section{Appendix A}
   Grounding line retreat & TODO\\
   Discharge + submarine melting & \citet{davison_2023}\\
   Split of discharge \& submarine melting & \citet{davison_2023}\\
-  Basal melting & \citet{pattyn_2010}\\
-  Regional distribution terms & See Sect. \ref{sec:methods:split}\\
+  Basal melting & \citet{van-liefferinge_2013}\\
   Drawdown or accumulation & Derived from above
 \end{tabular}
 \end{table*}