You have submitted GLOBE Observer Mosquito Habitat Mapper observations, but are still unsure how to access and analyze that data? This blog outlines the steps to download data into a spreadsheet, describes the data found in each column, and discusses what to do with the two sets of latitude and longitude data associated with each observation.
First you will need to download your data using GLOBE’s Advanced Data Access Tool (ADAT). This link also has video and text tutorials to get you started. Once you open ADAT, it prompts you to select filters, which will determine how much and what kind of data you will obtain.
As an example, let’s assume you want to examine all the GO Mosquito Habitat Mapper data from the U.S.:
Select filters you want:
Data Filters: Select Protocol: Mosquito Habitat Mapper. Click on green button, “add to filter.”
Site Filters: Select Country/State: United States. Click on green button, “add to filter.”
Finalize filter to obtain data: In upper left corner, click on green button, “apply filter.”
Under the number of Sites Found, select the green button, “Obtain Measurement Data.” (In most instances you will want more than the summary data). The data will download to your computer as a compressed ZIP file. Click to open, and you will see a spreadsheet, looking something like this:
Make a working copy of the spreadsheet
The first step is to make a copy of the original spreadsheet. Don’t modify the original spreadsheet because you may need to refer to it in the future. This is particularly important if you are downloading a large data set or have a slow connection.
Understand what data is contained in each column
The table below describes what data are found in each column of a downloaded GO Mosquito Habitat Mapper data sheet. For more information about the GLOBE database, consult the The GLOBE Data User Guide.
The next step is to format the downloaded spreadsheet so that it can be used in conjunction with your preferred analysis tools. This step is called data preparation. It is the preprocessing step that ensures that the data you work with are in a form that can be read by other programs. You will want to eliminate any information that is not pertinent to your analysis as well as ensure that data that you do want are in a usable and readable format.
Not all the information in the spreadsheet will be pertinent to your investigation. For most scientific investigations based on Mosquito Habitat Mapper data, the data columns H-AD will be useful to import into your analysis program. Columns A-G , on the other hand, may be useful to determine which rows or data you want to select (for instance, if you want to import all your own data, or all the data from a specific school), but you may want to delete these columns from your working spreadsheet prior to analysis.
Why are there two columns each for latitude, longitude, and elevation?
When preparing your data, be sure to eliminate one set of location coordinates in your data table, because analysis programs will not accept two sets of latitude and longitude measurements for a single observation. Data users unfamiliar with GLOBE data may be confused when they see two columns each for latitude, longitude and elevation: columns E, F, G and columns AC, AD, and AE, respectively (Fig. 4). Columns in red box provide location information of the GLOBE Sampling Site associated with the observation described in each row. The GLOBE convention is to identify a Sampling Site by the coordinates of the SW corner of the associated Military Grid Reference System (MGRS) grid box.
The location information in the blue box provides measured location information of the sample, as reported by user's GPS receiver in their mobile device. You can select either one of these location coordinate sets to use in your analysis.
What is MGRS?
GLOBE uses the Military Grid Reference System (MGRS) as a reference geographic coordinate system, and each observation has a MGRS coordinate assigned as it's GLOBE Sampling Site. You can read more about the MGRS grid in the GLOBE Data User Guide. For each unique observation (row) in the data set, the latitude, longitude, and elevation in in columns E, F and G were defined at the lower left corner of the associated MGRS grid box and refer to the coordinates of the observation's associated GLOBE Sampling Site (see Fig. 5, left). The “true” location of a GLOBE Observer measurement is the latitude and longitude recorded by the Global Position System (GPS) receiver from a person’s mobile device (see Fig. 5, right).
The next data preparation steps you will take depends on the analysis program or package you are planning to use. For a description of data preparation steps needed to import spreadsheet data into GIS mapping software, check out the webinars by GLOBE Master Trainer Dr. Becky Boger, Brooklyn College, and Dr. Joseph Kerski, ESRI.