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Preparing CERES Database Irradiance Variables

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Lauren Adoram-Kershner edited this page Jun 9, 2019 · 6 revisions

Introduction

The SAM weather modeling is dependent on NASA's CERES irradiance data. The irradiance variables used in the model can be found on a NASA database and downloaded. The files that can be downloaded from the NASA database are not in a format that the SAM will recognize. Therefore, the data needs to be read from these downloaded files and formatted in a specific way to be recognized and used in the model.

Downloading the Data

  1. Go to: https://ceres.larc.nasa.gov/order_data.php
  2. Find the SYN1deg data products (Synoptic TOA and surface fluxes and clouds) -> Browse & Subset
  3. Edition 4 -> Browse & Subset
  4. Under 'Adjusted TOA, Surface, and Profile Fluxes' select
    • 'Adjusted All-Sky Profile Fluxes' -> 'Shortwave Flux Down' -> 'Surface'
    • 'Adjusted Surface SW Direct and Diffuse Fluxes' -> 'Surface Shortwave Direct Flux' -> 'All Sky'
  5. Select Hourly Temporal Resolution, Global Spatial Resolution (0 to 360 and -90 to 90), and Terra+Aqua Edition 4A Satellite
  6. Enter time range of deployment
  7. Enter email address and select 'Get Data' button at the bottom of the page

If the data order exceeds 2 GB, the data will have to added to the shopping cart and ordered. Follow the instructions to complete order. This process will result in nc file downloads.

Formatting the Data

Use 'ncread' matlab function to open the files:

GHI = ncread(filename, 'adj_atmos_sw_down_all_surface_1h'); and DNI = ncread(filename, 'adj_sfc_sw_direct_all_1h');

This will produce matrices of size 360 x 180 x T, where T is the number of hours in the calendar months over which your deployment spanned. Split these matrices into monthly matrices of size 360 x 180 x days_in_month*24 and save to mat file with the naming convention, 'CERES_SYN1deg_1H_TrAq_Ed4a_[YEAR]_[MONTH]_SW_Irr_Flux.mat', where [MONTH] is always two numbers (e.g. 01 or 12).

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