A space and time surface radiation climatology of the ARM Southern Great Plains site

 
Poster PDF

Authors

Daniel Dean Hartsock — University of Oklahoma
Claude E. Duchon — University of Oklahoma
Peter J. Lamb — University of Oklahoma

Category

Radiation

Description

We are in the process of developing the surface radiation budget for the ARM Southern Great Plains (SGP) site using Solar and Infrared Radiation Station (SIRS) radiometers available at six extended facilities. Our goal is to derive a climatology of the monthly surface radiation budget from 1998 to the present. We currently are calculating the shortwave and longwave budgets and surface albedo for Pawhuska (EF12) as a prototype for the entire study. The SIRS data archive also contains data quality checks (QC) that we use to identify missing and questionable data. The automated QC began in 2002 and continues to the present. The years prior to 2002 require visual inspection.

The procedure for developing a monthly budget is as follows. The upward and downward longwave radiation measurements are summed over the 1440 minutes in a day, beginning at local midnight, to obtain a daily total. Each daily budget then is summed for the month to obtain the monthly budget. A day for accumulating the shortwave radiation begins near sunrise, with the first minute that an upward or downward component of radiation is greater than zero, and ends near sunset, when the component again becomes negative. One estimate of global downward shortwave radiation is directly measured; a second estimate is computed from direct solar and diffuse sky measurements. There is but one estimate of the upward shortwave component. Each of the components is summed minute-by-minute throughout the course of the day to yield a daily sum in units of MJ/m**2. The same procedure is applied each day of the month to yield a monthly sum for each component.

To date, we have developed for EF12 a monthly summary table for each month, along with time series plots of the daily and monthly components of shortwave and longwave radiation. We currently are visually inspecting all data flagged as ‘bad’ or missing because we have found cases in which neither condition is correct. The tables and time series will be finalized after we determine replacement values for bad and missing data. Thus, an associated goal is to assess the reliability and robustness of the data set across the 14+ years of records and make appropriate adjustments. Similar analyses will be applied to the remaining five extended facilities that were considered to have the most spatially homogeneous surface properties among all extended facilities.