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Remote Sensing Practice Test — Medium Level

A free 10-question Remote Sensing practice test for Science Olympiad, written at regional and state level. Every question and answer choice is listed below — correct answers and scoring are revealed when you take the timed test.

10 questions15 min timedMedium levelAI-generated — verify answers against reliable sources
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1. A satellite instrument can distinguish 4096 different brightness levels in each pixel, allowing it to detect very subtle changes in reflected light from the land surface. Which type of resolution is being described?

  • A.A) Spatial resolution
  • B.B) Temporal resolution
  • C.C) Spectral resolution
  • D.D) Radiometric resolution

2. A researcher is using Landsat-like imagery (30 m spatial resolution) to monitor drought impacts on cropland over a 10-year period. They compute NDVI for each image date. In a given field, the mean NDVI in early July decreases from 0.78 in a wet year to 0.42 in a drought year, while nearby urban areas remain near 0.10 both years. What is the most reasonable interpretation of this NDVI change in the field?

  • A.A) The decrease in NDVI indicates reduced vegetation greenness and density in the field, consistent with drought stress
  • B.B) The decrease in NDVI indicates a shift from vegetation to open water in the field, caused by increased irrigation during drought
  • C.C) The decrease in NDVI indicates that the sensor’s radiometric resolution has degraded over time, not an actual vegetation change
  • D.D) The decrease in NDVI indicates the field has been converted to urban land cover, similar to the nearby city

3. A satellite sensor records surface reflectance values over a cropland field as NIR = 0.52 and Red = 0.18. Using the NDVI formula NDVI = (NIR − Red) / (NIR + Red), what is the NDVI for this field, and therefore which value would you expect to see in the NDVI image for this pixel? (Assume values are rounded to two decimal places.)

  • A.A) 0.12
  • B.B) 0.35
  • C.C) 0.49
  • D.D) 0.78

4. Two pixels from a satellite image are analyzed to monitor vegetation change related to drought using NDVI. Pixel 1: NIR reflectance = 0.60, Red reflectance = 0.20 Pixel 2: NIR reflectance = 0.40, Red reflectance = 0.30 Based on the NDVI formula, (NIR − Red) / (NIR + Red), which statement is most accurate?

  • A.A) Pixel 1 has the higher NDVI and likely healthier vegetation
  • B.B) Pixel 2 has the higher NDVI and likely healthier vegetation
  • C.C) Both pixels have the same NDVI because their total reflectance (NIR + Red) is similar
  • D.D) NDVI cannot be compared between these pixels because only red reflectance matters for vegetation health

5. You are designing a satellite-based study to track daily development and movement of large storm systems that can trigger extreme rainfall events under a warming climate. Which combination of orbit and sensor type is best suited for this objective?

  • A.A) Geostationary orbit with a multispectral passive optical imager providing images every 5–15 minutes
  • B.B) Sun-synchronous polar orbit with a high-resolution (1 m) optical camera revisiting every 16 days
  • C.C) Sun-synchronous polar orbit with a lidar instrument measuring vertical profiles over a narrow ground track once per month
  • D.D) Medium Earth orbit with a synthetic aperture radar (SAR) sensor revisiting the same location every 10 days

6. You are using Landsat-like imagery (30 m spatial resolution) to monitor deforestation in a rectangular region that is 90 km east–west and 60 km north–south. Assuming every pixel is 30 m × 30 m and the image covers the area without gaps, approximately how many pixels represent this region? (1 km = 1000 m)

  • A.A) 60,000 pixels
  • B.B) 600,000 pixels
  • C.C) 6,000,000 pixels
  • D.D) 60,000,000 pixels

7. A research team wants to map how forest canopy height and structure are changing in a mountain region as the climate warms, in order to estimate changes in aboveground carbon storage. Which type of sensor would be most appropriate for directly measuring the 3D structure of the forest canopy from space or aircraft?

  • A.A) Passive multispectral optical sensor (e.g., Landsat, Sentinel-2)
  • B.B) Thermal infrared radiometer measuring surface temperature
  • C.C) Lidar system that uses laser pulses to measure distances to the canopy and ground
  • D.D) Passive microwave radiometer measuring natural microwave emission from the surface

8. A team is comparing long-term sea level rise with coastal subsidence to assess flooding risk for a delta city. They want to combine GRACE data, a satellite altimetry record (e.g., Jason series), and Sentinel-1 radar imagery in a GIS. Which pairing best matches each dataset with the climate-related quantity it primarily contributes to this analysis?

  • A.A) GRACE → groundwater and mass changes; Altimetry → absolute sea surface height; Sentinel-1 → land surface deformation and subsidence
  • B.B) GRACE → land surface deformation; Altimetry → groundwater storage; Sentinel-1 → sea surface temperature patterns
  • C.C) GRACE → cloud water content; Altimetry → rainfall intensity; Sentinel-1 → ocean surface salinity
  • D.D) GRACE → vegetation health; Altimetry → shoreline position; Sentinel-1 → atmospheric water vapor profiles

9. Different satellite missions are used to monitor various components of the climate system. Which pairing correctly matches the mission with the primary Earth system variable it is best known for measuring?

  • A.A) GRACE – long-term sea surface temperature patterns
  • B.B) SMAP – near-surface soil moisture related to drought and flooding
  • C.C) SWOT – atmospheric carbon dioxide concentrations over Mauna Loa
  • D.D) Jason series – groundwater storage changes in large aquifers

10. Students design an experiment to quantify deforestation and its impact on local surface temperature between 2005 and 2025 using freely available satellite data. They can access Landsat-like optical/thermal data (30 m, 16-day revisit) and MODIS-like data (coarser spatial resolution, near-daily revisit). Which approach best balances spatial detail and climate-relevant information?

  • A.A) Use Landsat-like optical bands to map forest cover change at 30 m, then extract surface temperature trends over forested vs. deforested pixels from the Landsat-like thermal band
  • B.B) Use only MODIS-like coarse-resolution NDVI to estimate forest loss, assuming surface temperature is the same for all land covers at that scale
  • C.C) Use Landsat-like true-color (visible only) images to visually estimate forest loss and use ground thermometers for temperature, ignoring satellite thermal data
  • D.D) Use only MODIS-like sea surface temperature data as a proxy for local land surface temperature change due to deforestation

Questions are AI-generated for Remote Sensing practice and can contain mistakes — check answers against reliable sources. Take the timed version to see correct answers, scoring, and explanations: start the Remote Sensing test.