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Advanced Webinar: Applications of GPM IMERG Reanalysis for Assessing Extreme Dry and Wet Periods

Date Range: 
January 28, 2020. January 30, 2020. February 4, 2020.

It is well recognized that long-term precipitation measurements are necessary for understanding and monitoring regional precipitation characteristics. This includes characteristics crucial for monitoring water resources and hazards, like floods and droughts. TRMM was the first NASA mission dedicated to observing precipitation. It operated from November 1997 to April 2015. The Global Precipitation Measurement (GPM) Mission launched in February 2014 as a follow-on to TRMM. Both TRMM and GPM satellites, together with additional national and international satellites, were used to produce multi-satellite products such as TMPA and IMERG. Until recently these two separate products covered different time periods. There was a lack of long-term, continuous, precipitation time series. 

Recently, GPM-IMERG retrospectively analyzed TRMM-TMPA data to produce a consistent, combined precipitation time series from 2000-present. This extended IMERG data product is available at half-hourly resolution and 0.1x0.1 degree spatial resolution. The product will be useful for deriving long-term mean precipitation as reference. It will also help with monitoring extreme precipitation at regional scale.

Past ARSET trainings on water resources and flood management covered TMPA and IMERG data and their applications in detail. This advanced webinar will focus on analysis and interpretation of the new long-term IMERG data, focused on extreme dry and wet period monitoring and management. The webinar will include lectures and hands-on exercises to derive regional precipitation statistics.

Learning Objectives: 

By the end of this training, attendees will be able to: 

  • Derive regional precipitation statistics (mean, standard deviation, anomalies, percentile values) 
  • Calculate and interpret the Standardized Precipitation Index (SPI) for assessing extreme dry and wet periods
Course Format: 
  • Three, two-hour parts that include lectures and demonstrations, exercises, and question and answer sessions
  • There will be identical sessions at two different times of the day

Local, regional, state, federal, and international entities, including public and private sector organizations, engaged in water resources and disaster management.

Course Agenda: 
Part One: Calculation of Precipitation Statistics Using IMERG

This session will provide a brief overview of IMERG data including its strengths and caveats and how to access and download IMERG data. The lecture will then follow with a hands-on exercise on the calculation of regional statistics utilizing precipitation IMERG data.



Part Two: Calculate Standardized Precipitation Index (SPI) based on IMERG to Monitor Wet and Dry Conditions

This session will show attendees how to calculate SPI on defined time scales of 1 to 3 months as well as diagnosis of wet and dry conditions based on SPI. The session will then follow with an exercise calculating SPI on 1 to 3 month time scales.



Part Three: Flood and Drought Risk Assessment Based on SPI

This session will focus on the analysis of SPI for ~20-year period (2000 to present) to assess the frequency and spatial extent of extreme wet and dry conditions, together with socioeconomic data to understand flood and drought risk.



Application Area: 
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