Atmospheric Brown Cloud

The Indian Ocean Experiment (INDOEX) carried out in February 1999 in the islands of the Maldives revealed a 3 km-thick toxic umbrella, or ‘Brown Cloud’, stretching over Afghanistan, Pakistan, Bangladesh, Bhutan, India, the Maldives, Nepal, and Sri Lanka, which are among the most densely populated places in the world. The finding came from observations gathered by more than 200 scientists supplemented by satellite readings and computer modelling. The haze is 80 percent man-made and composed of a grimy cocktail of toxic ash, black carbon, sulphate, nitrates, acids, and aerosols – tiny solid or liquid particles suspended in the atmosphere. The haze can extend far beyond the Indian subcontinent. Nobel Laureate Paul Crutzen and Prof. V. Ramanathan visited Kathmandu in March 2001 to discuss the situation supported by UNEP and coordinated by ICIMOD, and followed up by conducting a pilot study. The year-long study was very informative and led to a long-term study to elucidate the exact reasons for the cloud. A permanent observatory known as the Nepal Climate Observatory (NCO) was setup at ICIMOD Headquarters and the ICIMOD Knowledge Park at Godavari at Godavari and equipped with radiation, aerosol, and rainwater chemistry measurement instruments, and meteorological instruments. This project relates to the implementation of the Nepal observatory and measurement protocols, and is now in the third phase (Phase II).


Phase II: 2010 - 2012
Phase I: 2004 - 2009
Pilot Phase: 2002 - 2003

Geographical coverage

Nepal at two locations

  1. Godavari, Lalitpur (27.59°N,  85.38°E, 1590 m above mean sea level)
  2. ICIMOD Headquarters, Khumaltar (27.38°N, 85.19°E, 1315 m above mean sea level)

Core financial partners/development partners/sponsors

Implementing partners

Supported by research work at the universities.

Contact information

Bidya B. Pradhan
Environment Officer, MENRIS