It is instructive to recall the definition of an extreme weather and extreme climate events as provided in the IPCC 5th Assessment Report (WG 1 Glossary):
"An extreme weather event is an event that is rare at a particular place and time of year. Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of a probability density function estimated from observations.  By definition, the characteristics of what is called extreme weather may vary from place to place in an absolute sense.  When a pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total that is itself extreme (e.g., drought or heavy rainfall over a season)."

High-resolution products, potentially useful for the SWCEM, are available, often on a quasi-real time basis, e.g. for monitoring precipitation, land surface temperatures, soil moisture and vegetation.  The existence and adequacy of such products provides opportunities to evaluate the products for monitoring extreme weather and climate events on a short-term (pentad (5-day) or weekly) basis.  Although it is likely that current satellite products alone may be not fully adequate from the beginning, the quasi-operational use of the satellite products in a demonstration phase will, in conjunction with surface-based observations, help to improve quality and contributions of the satellite products themselves.  A unique advantage of satellite observations is their larger scale spatial coverage which complements the potentially more accurate but spatially sparse ground-based observations.


The SWCEM Demonstration Project (SEMDP) East Asia and Western Pacific regional subproject (SEMDP-EAWP) began in 2018 with a duration of two years.  The invited WMO RCCs and NMHSs in the SEMDP regional subproject have validated satellite derived products with CLIMAT and/or SYNOP data for monitoring persistent heavy/little rainfall and drought.  It is a goal to do the monitoring over relatively short periods from pentads (5-day) up to a month.  It is noted that currently extreme events are rather diagnosed on a monthly basis by most of the RCCs.  For drought events a period of about a month is considered.

The 2-year SEMDP-EAWP has concentrated on products at national and regional levels.  Items to be worked on include:

  • Monitoring persistent heavy/little rainfall and droughts;
  • Making best use of existing and newly developed satellite derived products and time series of measurements;
  • Making best use of products that combine satellite information with in-situ data;
  • Validating satellite derived products with surface-based observations;
  • Making use of recommended practices for monitoring extreme weather and climate events;
  • Recommendations as to which products should be transitioned from research to operations, including an assessment of those products.

SWCEM-EAWP in Operation

A couple of RCCs have already volunteered to pursue SEMDP-EAWP over a period of two years.  After the demonstration phase, the results of monitoring with satellite derived products will be reviewed and reflected in the SWCEM East Asia and Western Pacific regional operational subproject (SWCEM-EAWP).

The Eighteenth World Meteorological Congress (Cg-18) in June 2019 adopted the SWCEM Implementation Plan, endorsed its implementation from 1 January 2020, and requested technical commissions and relevant regional associations:

  1. To establish a consultative process to assist Members and relevant international organizations and programmes with the implementation of the SWCEM regional operational subproject implemented in East Asia and Western Pacific, as well as connecting with the existing activities, such as RA II WIGOS Project, RA V TT-SU (Task Team on Satellite Utilization) and AOMSUC (Asia/Oceania Meteorological Satellite Users’ conference);
  2. To develop an action plan for phased SWCEM implementation with strengthened end-user engagement;
  3. To consider the possibility of implementing similar projects in Africa and South America;

and invites the relevant international organizations and programmes to contribute to and support the implementation of the SWCEM regional operational subproject in East Asia and Western Pacific.

Related Documents

SWCEM Steering Group Meetings