Special Observations
Special Observations can only be scheduled during the 9 or 10 orbit gaps in the Global Surveys, and are conducted in any of three basic modes:
- Stare: In nadir mode, point at specific locations over sites for validation and other scientific interest for up to about 4 minutes. Such observations are made for as long as the target is in within ±45° of the nadir direction (up to 210 seconds).
- Transect: In nadir mode, point at a set of contiguous areas to cover about 850 km, or indefinitely in limb mode.
- Step-&-Stare: Point at nadir for 4 seconds (5.2 seconds with necessary reset). During that time, Aura moves 39 km in its orbit, and its nadir point on Earth's surface moves 35 km. Point at nadir again. Repeat indefinitely.
The mode used -- targeted, transect, step-and stare, or limb -- depends on the science requirement. Volcanoes, for example, would usually be targeted with the stare mode (point at the caldera and hold the view there for as long as possible). Biomass burning, on the other hand, could use any mode depending on whether we wish to measure the fire itself or look for specific gases in the plume coming from the fire. Limb transects are normally used for intercomparison with the other Aura instruments.
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).
| ARM site |
TES footprint mean elevation (m) |
Coordinates (Decimal Degrees) |
Approx. Aura (Ascending) Overpass Time |
| Latitude |
E. Longitude |
Local Mean Solar Time |
Coordinated Universal Time |
| Southern Great Plains |
314 |
36.617 |
262.500 |
14:02:37 |
20:32:37 |
| Barrow, Alaska |
2 |
71.323 |
203.384 |
15:19:04 |
1:45:32 |
| Barrow. Alaska, off-shore pt. |
0 |
71.400 |
203.200 |
15:19:33 |
1:46:45 |
| Atqasuk, Alaska |
18 |
70.472 |
202.592 |
15:14:01 |
1:43:49 |
| Manus Island |
1 |
-2.058 |
147.425 |
13:36:49 |
3:47:07 |
| Manus Island, off-shore pt. |
0 |
-2.180 |
147.450 |
13:36:44 |
3:46:56 |
| Nauru Island |
5 |
-0.521 |
166.916 |
13:37:42 |
2:30:02 |
| Nauru Island, off-shore pt. |
0 |
-0.500 |
166.820 |
13:37:43 |
2:30:26 |
| Darwin, Australia |
1 |
-12.425 |
130.891 |
13:30:43 |
4:47:09 |
| Darwin, Australia, off-shore pt. |
0 |
-12.320 |
130.780 |
13:30:47 |
4:47:39 |
The NASA Network for the Detection of Stratospheric Change (NDSC) also makes useful tropospheric measurements (see table below).
| NDSC site |
TES footprint mean elevation (m) |
Coordinates (Decimal Degrees) |
Approx. Aura (Ascending) Overpass Time |
| Latitude |
E. Longitude |
Local Mean Solar Time |
Coordinated Universal Time |
| Table Mountain, CA |
1905 |
34.400 |
242.300 |
14:00:41 |
21:51:29 |
| Lauder, NZ |
379 |
-45.040 |
169.680 |
13:04:46 |
1:46:03 |
| Hilo, Hawaii |
11 |
19.720 |
204.930 |
13:49:51 |
0:10:08 |
| Hilo, off-shore pt. |
0 |
19.800 |
205.000 |
13:50 |
0:10 |
| Reunion Island |
10 |
-21.800 |
55.500 |
13:24:46 |
9:42:46 |
| Reunion Island, off-shore pt. |
0 |
-21.400 |
55.500 |
13:25 |
9:43 |
Other sites which are useful for up-welling radiance measurements, some of which are used for calibrating the Pointing Control System (PCS), are listed in the table below.
| Location |
TES footprint mean elevation (m) |
Coordinates (Decimal Degrees) |
Approx. Aura (Ascending) Overpass Time |
| Latitude |
E. Longitude |
Local Mean Solar Time |
Coordinated Universal Time |
| Lake Tahoe, CA |
1898 |
39.100 |
239.970 |
14:04:50 |
22:04:50 |
| Lake Tahoe, CA (N. shore) |
1905 |
39.240 |
239.940 |
14:05 |
22:05 |
| ASTER site (MN lakes) |
TBD |
TBD |
TBD |
TBD |
TBD |
| Chesapeake Lighthouse |
0 |
TBD |
TBD |
TBD |
TBD |
| Mediterranean |
0 |
TBD |
TBD |
TBD |
TBD |
See TES Special Observation Target Locations (GIF, 25 KB) 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.
| Name |
Location |
Latitude |
Longitude |
| Colima |
Mexico |
19.420 |
256.280 |
| Erebus |
Antarctica |
-77.525 |
167.120 |
| Etna |
Sicily |
37.730 |
15.000 |
| Fuego |
Guatemala |
14.480 |
269.120 |
| Kilauea/Pu'u O'o |
Hawai'i |
19.392 |
204.892 |
| Lascar |
Chile |
-23.370 |
292.270 |
| Masaya |
Nicaragua |
11.980 |
273.850 |
| Pacaya |
Guatemala |
14.380 |
269.400 |
| Sakurajima |
Japan |
31.580 |
130.670 |
| White Island |
New Zealand |
-37.520 |
177.180 |
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).
| Location |
Elevation (m) |
Latitude (°) |
Longitude (°) |
| Ascension Island |
429 |
<-7.95 |
<-14.37 |
| East Mediterranean |
0 |
35.0 |
32.0 |
| Saudi Arabia |
777 |
25.0 |
45.0 |
| Oklahoma |
171 |
35.0 |
265.0 |
The schematic below shows the footprint for 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).
| Number of scans/step |
Maximum Transect Length (km) |
| 1 |
949 |
| 2 |
349 |
| 3 |
220 |
| 4 |
132 |
Limb transect mode observations are primarily used for instrument intercomparisons and are created by putting TES into its limb mode and making repetitive long scans.
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.
Archived Special Observations Data
Archived data are 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. Specific pages for acquiring TES data are the ASDC TES Data Sets page, and the AVDC (scroll down for TES data links).
