Day 6

10am-6pm

-downloaded the student version of MATLAB.

We decided that it would be best to work from my computer and have all the matlab and files I needed on my laptop so I could have it with me for future reference. It cost me about 100 smakeroos, but I guess that is what I'm getting paid for. I need to get a C compiler on my computer and then I should be all set. All the IDL stuff is on her laptop still though. Not really sure how I will be able to transfer between the two.

-Prepped input files to run the model for Gulkana in IDL.

This was a lot more complicated than it sounds. In order to calculate melt, the model needs the solar geometry of the topographic area to calculate the direct radiation. Using IDL we created grids for aspect and slope and DEM (elevation). Once all of this was working we looked at the DEM for the Gulkana drainage basin. The data from the USGS was incomplete and missing a section. This was not good. With the help of Anna in hydrology, we were able to use the drainage basin she had created and multiply it by the DEM for the total area and fill in the missing values. Once we had a complete and accurate drainage basin, we ran the direct radiation program in C++. The output for this comes in the form of a binary file for the average direct radiation for every day for a year. This does not change from year to year and we can look at each file as a grid in IDL. The model then uses this information to help calculate melt.

We also talked about the difference between firn and ice. At the end of the summer when the most melt has occured, firn is the snow that stays on the glacier where as ice is the ice. The firn has a much higher albedo and reflects a lot more light than ice because ice is darker, therefore the two have different melt factors. This is acknowledged in Regine's model and is another input file that the model uses to calculate total melt.

After using IDL and C more today I feel a little more comfortable navigating in these programs and I feel like I'm getting a better sense of the model and the multiple components that it contains. Regine explained to me that we have the simple temperature-index model which is simply a degree day factor (DDF), two different ones for ice and snow, multiplied by a temperature. Then her more refined model breaks down the DDF into a melt factor and radiation based on topography because different slopes and aspects will have different melt.

After today we now have all the input files needed to run her more refined model and to create an output simulated discharge. Hopefully this is what we will accomplish tomorrow. This is just so I can get a general sense of how to run the model and all the dials and nobs that need to be refined and tuned. The meat of the project then is comparing the simulated discharge to the discharge data from the USGS (which we still need to obtain) and then calibrate the model to fit the two data sets as close together as possible. All the while, also working on putting everything into MATLAB.

-I got on board doing some field work in Yakutat for a few weeks at the end of August with Barbara. I'm really excited about this and looking forward to it!