Special (Research) Observations fall into three general categories:

• The first category includes targeted staring nadir observations of specific locations over sites for validation and other scientific interest. Such observations are made for as long as the target in within ±45° of the nadir direction (up to 210 seconds).
• The second category makes transect observations in the down-looking mode, covering about 900 km along the Aura orbit, or indefinitely in the limb mode.
• The third category makes consecutive nadir observations (the step & stare mode) for a latitude range along the Aura orbit.
• Special Observations can only be scheduled during the 9 or 10 orbit gaps in the Global Surveys.

Special Observation data is available from the Aura Validation Data Center (AVDC) at the Goddard Space Flight Center. Additionally, the data may be found and ordered from the Atmospheric Science Data Center (ASDC) at the Langley Research Center.

The data may be found and ordered at the following data pools:

• AVDC TES Instrument Data
• ASDC TES Data Sets

Modes and Types of Special Observations

Staring Mode Observations

• The Staring Mode is used for localized validation, volcano monitoring, and biomass burning observations.
• Adjustments to the following tables will be made at the discretion of the TES Science and Validation Teams.

Validation Sites

• There are a number of permanently-instrumented validation sites around the world.
• Some of the most useful sites for TES are those participating in the DoE Atmospheric Radiation Measurements (ARM) program (see table below).

• The NASA Network for the Detection of Stratospheric Change (NDSC) also makes useful tropospheric measurements (see table below).

• The sites listed in the table below are other locations that can be used for up-welling radiance measurements, some of which will be useful for calibrating the Pointing Control System (PCS).

See TES Special Observation Target Locations for a look at the locations around the world.

Volcanoes

• There are 10 volcanoes that the volcanology community is interested in having TES monitor (see table below).
• Each of these volcanoes emits copious amounts of gas (chiefly sulfur dioxide), the exact mixture of which is believed to be an eruption predictor.

Biomass Burning & Major Industrial Accidents

• Biomass burning, especially in the tropics in the September-October time frame, is a major source of atmospheric pollutants.
• Most burnings can be observed by TES with a delay of 48 hours or less depending on when the information is received.
• Major industrial accidents can be targeted if information is received in a timely manner.

Transect Mode Observations

• The Tansect Mode is used primarly for regional pollution studies and validation campaigns.
• The following table identifies the TES transect locations (which are subject to change).

• The figure below shows a schematic of the footprints for the Transect Mode.

Schematic of a segment of the TES transect mode (keystoning exaggerated for clarity)

• Multiple scans can be made at each step location; however, the overall length of the transect is limited to ±45� nadir angle (see table below).

• Limb transect mode observations are primarily used for instrument intercomparisons and are created by putting TES into its limb mode, making repetitive long scans.

Nadir-Only (Step & Stare) Mode

• The consecutive nadir scans are designed for research and validation purposes. Similar to the global survey nadir scans, the TES pointing control system will point the instrument to stare at a nadir location for the period of one or two scans and step forward to the next location along Aura's orbit.
• In single-scan mode, the distance between two consecutive nadir scans is about 35 km along Aura orbit.

Special Tests and Calibrations

• TES has a variety of test and calibration modes. Some involve the acquisition of interferograms, many do not. All of these tests are performed regularly for the life of the mission.