Drought

Lake Chad has shrunk dramatically over the last four decades due to a decrease in rainfall and an increase in the amount of water used for irrigation projects. Its surface area was 25 000 sq km in the early 1960s, compared with 1350 sq km in 2001. Image acquired 19 December 2007 by the MERIS (Medium Resolution Imaging Spectrometer) instrument aboard ESA’s Envisat satellite. Image: ESA, CC BY-SA 3.0 IGO.

Definition

Drought may be considered in general terms a consequence of a reduction over an extended period of time in the amount of precipitation that is received, usually over a season or more in length. It is a temporary aberration, unlike aridity, which is a permanent feature of the climate. Seasonal aridity (i.e., a well-defined dry season) also needs to be distinguished from drought. It should be noted that drought is a normal, recurrent feature of climate, and it occurs in virtually all climatic regimes (UNDDR).

Facts and figures

Droughts are often predictable: periods of unusual dryness are normal in all weather systems. Advance warning is possible (WHO).

By 2025, 1.8 billion people will experience absolute water scarcity, and 2/3 of the world will be living under water stressed conditions (UNCCD).

Drought can be defined according to meteorological, agricultural, hydrological and socio-economic criteria.

  • Meteorological, when precipitation departs from the long-term normal
  • Agricultural, when there is insufficient soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought is typically evident after meteorological drought but before a hydrological drought
  • Hydrological, when deficiencies occur in surface and subsurface water supplies
  • Socio-economic, when human activities are affected by reduced precipitation and related water availability. This form of drought associates human activities with elements of meteorological, agricultural, and hydrological drought (FAO).

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SAM Satellite

GOES-16 currently serves as the operational geostationary weather satellite over the U.S. East coast. Later this year, GOES-17 will become operational as the GOES West satellite.

Both belong to the GOES-R series focuses on the detection and observation of environmental phenomena that directly affect public safety. The satellites provide advanced imaging with increased spatial resolution and faster coverage for more accurate forecasts, real-time mapping of lightning activity, and improved monitoring of solar activity and space weather.

The GOES-R Series is a four-satellite program (GOES-R/S/T/U) that will extend the availability of the operational GOES satellite system through 2036. 

Instruments:
ABI (Advanced Baseline Imager)
GLM (Geostationary Lightning Mapper)
EXIS (Extreme Ultraviolet and X-ray Irradiance Sensors)
SUVI (Solar Ultraviolet Imager)
MAG (Magnetometer)
SEISS (Space Environment In-Situ Suite)

Launch date:
19/11/2016

The AlSat-1B satellite was launched into orbit on September 26, 2016 from the Satish Dhawan Space Centre in Sriharikota, India. It was developed by the Algerian Space Agency (ASAL) in corporation with Surrey Satellite Technology Ltd (SSTL). The AlSat-1B satellite orbits at 670 km above the earth's surface and carries a 24m multispectral imager and a 12m panchromatic imager delivering images with a swath width of 140km.  The satellite carries two High Speed Data Recorders and two Flash Mass Memory Units capable of recording, managing and storing image data for high speed downlink via S-Band and X-Band transmitters. The data collected by AlSat-1B helps monitor climatological disasters (forest fires, glacial lake outbursts, droughts) and hydrological disasters (landslides and floods).

 

Launch date:
26/09/2016

Gaofen-3 was launched into orbit on August 10, 2016 from Taiyuan Satellite Launch Center in China. It was developed by the China Center for Resources Satellite Data and Application (CRESDA). Gaofen-3 orbits at 755 km above the earth's surface and is fitted with a Synthetic Aperture Radar (SAR) sensor that makes use of microwaves in the electromagnetic C-band. The spatial resolution of its imagery ranges between 1 and 500 meters. The data collected by Gaofen-3 helps monitor climatological disasters (droughts) and hydrological disasters (landslides and floods).

Launch date:
10/08/2016

Cartosat-2 is an advanced remote sensing satellite with a single panchromatic camera (PAN) capable of providing scene-specific spot imageries for cartographic applications. The camera is designed to provide imageries with better than one meter spatial resolution and a swath of 10 km. The satellite will have high agility with capability to steer along and across the track up to + 45 degrees. It will be placed in a sun-synchronous polar orbit at an altitude of 630 km. It will have a revisit period of four days. The re-visit can be improved to one day with suitable orbit manoeuvres.

Several new technologies like two mirror on axis single camera, Carbon Fabric Reinforced Plastic based electro optic structure, lightweight, large size mirrors, JPEG like data compression, advanced solid state recorder, high-torque reaction wheels and high performance star sensors are being employed in Cartosat-2.

Beginning with Cartosat 2C, a Multi-spectral camera was added and a lower 505... read more

Launch date:
22/06/2016

Sentinel-1 is a two satellite constellation with the prime objectives of land and ocean monitoring. The goal of the mission is to provide C-Band Synthetic Aperture Radar (SAR) data continuity following the retirement of ERS-2 and the end of the Envisat mission.
To accomplish this the satellites carry a C-SAR sensor, which offers medium and high resolution imaging in all weather conditiions. The C-SAR is capable of obtaining night imagery and detecting small movement on the ground, which makes it useful for land and sea monitoring.
Sentinel-1 will work in a pre-programmed operation mode to avoid conflicts and to produce a consistent long-term data archive built for applications based on long time series.
The mission benefits numerous services. For example, services that relate to the monitoring of Arctic sea-ice extent, routine sea-ice mapping, surveillance of the marine environment, including oil-spill monitoring and ship detection for maritime security, monitoring... read more

Launch date:
25/04/2016

Carrying a suite of cutting-edge instruments, Sentinel-3 will measure systematically Earth’s oceans, land, ice and atmosphere to monitor and understand large-scale global dynamics. It will provide essential information in near-real time for ocean and weather forecasting.
The mission is based on two identical satellites orbiting in constellation for optimum global coverage and data delivery. For example, with a swath width of 1270 km, the ocean and land colour instrument will provide global coverage every two days. Sentinel-3A was launched on 16 February 2016.
With a focus towards our oceans, Sentinel-3 measures the temperature, colour and height of the sea surface as well as the thickness of sea ice. These measurements will be used, for example, to monitor changes in sea level, marine pollution and biological productivity.
Over land, this innovative mission will provide a bigger picture by monitoring wildfires, mapping the way land is used, provide indices of... read more

Launch date:
16/02/2016

Today, weather satellites scan the whole Earth, meaning not a single tropical storm or severe weather system goes undetected. The early detection and warnings they provide have saved thousands of lives.
Meteosat data is of unique value to nowcasting of high impact weather in support of safety of life and property.
It has been shown to improve weather forecasts and severe weather warnings which, in turn helps limit damage to property and benefits industry e.g. transport, agriculture and energy.
Meteosat-11 is the prime operational geostationary satellite, positioned at 0 degrees and providing full disc imagery every 15 minutes. It also provides Search and Rescue monitoring and Data Collection Platform relay service.

Instruments:
GERB (Geostationary Earth Radiation Budget)
MSG Comms (Communications Package for MSG)
SEVIRI (Spinning Enhanced Visible and Infra-Red Imager)
 

Launch date:
16/07/2015

The Sentinels are a fleet of satellites designed specifically to deliver the wealth of data and imagery that are central to the European Commission’s Copernicus programme.
Sentinel-2 carries an innovative wide swath high-resolution multispectral imager with 13 spectral bands for a new perspective of our land and vegetation. The combination of high resolution, novel spectral capabilities, a swath width of 290 km and frequent revisit times provides unprecedented views of Earth.
The mission is based on a constellation of two identical satellites in the same orbit, 180° apart for optimal coverage and data delivery. Together they cover all Earth’s land surfaces, large islands, inland and coastal waters every five days at the equator. Sentinel-2A was launched on 23 June 2015.
As well as monitoring plant growth, Sentinel-2 can be used to map changes in land cover and to monitor the world’s forests. It also provides information on pollution in lakes and coastal waters.... read more

Launch date:
23/06/2015

KOMPSAT-3A is the world’s first civilian satellite that is equipped with a high-resolution, infrared(MWIR) sensor which enables nighttime observation. It also provides the optical images with high resolution of 50 cm or less for the second in the world following the US.
The technology of improving the optical image quality by 30% or more without degradation using diagonal data to provide 38-cm-class images was developed for the second following the EU.
The high-resolution electro-optical spaceborne camera AEISS-A(Advanced Earth Imaging Sensor System-A) developed by KARI and accommodated on KOMPSAT-3A platform features 50cm class optical photography, which marks the highest resolution among cameras mounted on domestic satellites. The IR sensor, which is capable of detecting heat on the ground, is used to observe fire, volcanic activity and urban thermal islands during nighttime, even under any weather conditions.
KOMPSAT-3A operates in the sun’s synchronous orbit at... read more

Launch date:
26/03/2015

CBERS is a cooperative program between CAST (Chinese Academy of Space Technology) of the People's Republic of China, and INPE (Instituto de Pesquisas Espaciais) of Brazil (government agreement of both countries for the development and operation of two satellites). The program was signed in July 1988 to establish a complete remote sensing system (space and ground segment) to supply both countries with multispectral remotely sensed imagery.
In Nov. 2002, the governments of China and Brazil decided to expand the initial agreement by including another two satellites of the same kind, CBERS-3 and 4, as the second generation of the Sino-Brazilian cooperation effort. The planned cooperative CBERS-3&4 program of CAST and INPE employs enhanced versions of spacecraft and instruments. The specification of the project was agreed upon and closed in July 2004.

Instruments:
DCS (Data Collection System)
MUXCAM (Multispectral Camera)
PANMUX (... read more

Launch date:
06/12/2014

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