Home > analysis, sea ice > Northen hemisphere ice and snow area, first look

Northen hemisphere ice and snow area, first look

Image

Figure 1

Hemisphere area coverage of snow and ice for land and ocean. Early data has been excluded after discovering an anomaly with early daily sea ice data, excluded is early part which is every other day data.[1]

This is an experimental first attempt at creating a hemisphere ice coverage dataset.

Why? I don’t like hidden information, want to see for myself and perhaps shed more light on whatever is going on.

As with sea ice data there is a distinct increase in the amplitude of the annual cycle in recent years. No attempt has been made to produce a more regular annual cycle exclusion.

How was this done?

Best time resolution data is weekly for Rutgers and daily for g02315 NOAA sea ice.

Combining these two poses a problem.

  • land data is area
  • ocean data is extent only for daily data

I failed to find a computed law between extent and area so I took a pragmatic route. Noting the monthly g02135 datasets does give area and extent, and the difference between them (reported here) I told software to produce a crude model of the difference (easy for me to do).

Experimenting with the monthly data gave a good enough result

Image

Figure 2

Not perfect but reasonable. As it turns out ridiculously simple to do, literally the product of the model output and extent data. (was a bit of a huh! moment but if it works…)

Playing a party trick, all I have to do is change the model output to daily and it is ready to use with daily sea ice extent data.

As a final step I decided to output the result on the weekly data points rather than interpolate the land data to daily. Plots are figure 1.

Detailed work would probably refine the result slightly. Keep in mind the work might be a mistake and plain wrong.

Data. I’ve not provided anything, takes time and effort. If you want data, discuss.

Data sources.

Sea ice ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/
Snow http://climate.rutgers.edu/snowcover/

1. Sea ice every other day seems to be all there is. Published by NOAA seems to be a version of the earlier NASA STEREO dataset. It’s possible the distinct change when the data moved to literally daily is real but coherent with a sampling change is notable. Not been investigated, particularly what precisely changed.

Advertisements
Categories: analysis, sea ice
  1. No comments yet.
  1. No trackbacks yet.

Leave a reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: