Lectures 3 Flashcards

Question

Sea Surface Temp

Answer 1

The temperature of the sea is the most important parameter in understanding the role of the ocean as a heat reservoir. SST is an important geophysical parameter, providing the boundary condition used in the estimation of heat flux at the air-sea interface. On the global scale this is important for climate modeling, study of the earth's heat balance, and insight into atmospheric and oceanic circulation patterns and anomalies (such as El Niño)

Answer 2

SST can be derived from two types of satellite data, thermal infrared and passive microwave:  Thermal sensors  Sensors used for deriving SST include AVHRR, Along Track scanning Radiometer (ATSR), GOES, MODIS  good spatial resolution and accuracy  long heritage (over 30 years)  with thermal infrared (8-14 μm) the skin temperature (20 μm) at the sea-air interface can be measured  TIR measurements are affected by water vapor and clouds in the atmosphere, thus  atmospheric corrections are required Sea Surface Temperature (SST) Passive microwave sensors  PM sensors include SMMR, SSM/I, TMI, AMSR  clouds are transparent  long heritage (over 30 years)  relatively insensitive to atmospheric effects  lower spatial resolution and accuracy than with thermal, Due to lower signal strength of the Earth's Planck radiation curve in the microwave region  sensitive to surface roughness (waves) and precipitation  measures SST at depth of 1 mm

Answer 3

Three methods can be used: * Split window: uses 2 channels (windows) that overlap in spectral sensitivity (formula coefficients differ day / night) * Dual window: uses 2 channels that do not overlap * Triple window: uses 3 channels

Answer 4

* Ocean is important as the atmosphere in transporting heat * Mechanism is ocean currents * Warm ocean currents transport warm water from the tropics northward where they release energy to the air * Cold ocean currents transport cold water from higher latitudes toward the equator

Answer 5

```  Winds  Bottom topography  Sea-surface height  Sea-surface temperature  Coriolis forces resulting from the rotation of the earth ```

Answer 6

The factor influencing the oceanic circulation determines the platform Sea Surface Height • Early platforms are Geosat and ERS-1 were designed for the remote estimation of sea-surface height • NASA/CNES satellite TOPEX/POSEIDON, a sea- surface height sensor of high accuracy with an RMS error of 4.7 cm for TOPEX and 5.1 cm for POSEIDON • Jason-1 (similar to TOPEX/POSEIDON)

Answer 7

``` NASA scatterometer (NSCAT)  produced data from Sept 1996 - June 1997  C-band  50 km grid resolution  QuikSCAT SeaWinds scatterometer  June 1999-November 2009  C-band  25 km spatial resolution for wind vectors  measures winds of 3- 20 ms-1, with 2 ms-1 accuracy  ERS1/2 scatterometer,  Advanced scatterometer (ASCAT) METOP-A launched Oct. 2006 METOP-A launched Sept. 2012 METOP-C Planned 17 ```

Answer 8

Altimeters

Answer 9

* Backscattered energy indicates surface roughness * Orientation in imagery determines direction ex: ERS-2 SAR

Answer 10

Holy Child--always happens during x-mas Unusual warming extensive ocean warming in the equatorial eastern Pacific along the coast of Peru and Ecuador. brings nutrient-poor tropical water southward along the west coast of South America in major events that recur at intervals of 3-7 years. associated with atmospheric circulations having important consequences for weather and climate around the globe.

Answer 11

unusually cold ocean temperatures in the Equatorial Pacific

Answer 12

At higher latitudes, El Niño and La Niña are among a number of factors that influence climate * most clearly seen in wintertime * El Niño : warmer winter in the North Central States cooler in the Southeast and the Southwest * La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest

Answer 13

Over the ocean: * Microwave emissivity of rain (liquid water) is about 0.9 * Emissivity of the ocean is much lower (0.5) * Changes in emissivity (as seen by the measured brightness temperature) provide and estimate of surface rain rate Over the land surface: * Microwave scattering by frozen hydrometeors is used as a measure of rain rate * Physical or empirical models relate the scattering signature to surface rain rates

Answer 14

* Precipitation Radar (PR) * TRMM Microwave Imager (TMI) * Visible and Infrared Scanner (VIRS) * Cloud and Earth Radiant Energy Sensor (CERES) * Lightning Imaging Sensor (LIS)

Answer 15

Gravity Recovery and Climate Experiment Lake water storage anomalies Terrestrial water storage

Answer 16

Hyperspectral imager--more than 200 bands, with 10-nm bandwidth

Answer 17

* Physical basis * Spectral refelctance * Assessment of plant stress * Vegetation classification * Estimation of biomass * Angular reflectance characteristics * Vegetation indices * Phenological cycles * Multi-sensor, multi-resoltuion considerations