GATE 2019 Paper with Answer Keys for Atmospheric and Oceanic Sciences (XE-H)
Q. 1 – Q. 7 carry one mark each & Q. 8 – Q. 11 carry two marks each.
XE (B to H): Q. 1 – Q. 9 carry one mark each & Q. 10 – Q. 22 carry two marks each.
XL-P:
Q. 1 – Q. 5 carry one mark each & Q. 6 – Q. 15 carry two marks each
XL (Q to U): Q. 1 – Q. 10 carry one mark each & Q. 11 – Q. 20 carry two marks each.
Q.1- In the equatorial belt, the Madden-Julian Oscillation (MJO) propagates
(A) northward
(B) southward
(C) eastward
(D) westward
Ans: (C) eastward
Q.2- Potential temperature increases with height in an atmosphere. Upon adiabatic vertical displacement, a parcel of dry air is
(A) stable
(B) absolutely unstable
(C) neutral
(D) conditionally unstable
Ans: (A) stable
Q.3- Oxygen minimum zones in the ocean are formed in the layers where
(A) Photosynthesis is dominant
(B) Sunlight is maximum
(C) Decomposition of organic matter is dominant
(D) Iron availability is maximum
Ans: (C) Decomposition of organic matter is dominant
Q.4- Water level in an estuary rises and falls in response to tidal forces. Assume that the only tidal period in an estuary is 12 hours. The speed of the ebb current in that estuary would be maximum
(A) At high tide
(B) At low tide
(C) About 3 hours after high tide
(D) About 6 hours after low tide
Ans: (C) About 3 hours after high tide
Q.5- The most abundant ions in seawater are
(A) Sodium and chloride ions
(B) Magnesium and chloride ions
(C) Calcium and chloride ions
(D) Magnesium and sulphide ions
Ans: (A) Sodium and chloride ions
Q.6- Which among the following statements is true with respect to the axis of the Indian monsoon trough
(A) Relative vorticity is cyclonic at 850 hPa
(B) Relative vorticity is anticyclonic at 850 hPa
(C) It shifts to the south during break monsoon
(D) It moves to the head Bay of Bengal when a monsoon depression is present over the Indian subcontinent
Ans: (A) Relative vorticity is cyclonic at 850 hPa
Q.7- A student considered the following possibilities regarding trade wind inversion:
(P) Zonal component of wind is westerly
(Q) Zonal component of wind is easterly
(R) Meridional component of wind is poleward
(S) Meridional component of wind is equatorward
The only combination of correct statements is
(A) P,S
(B) Q,S
(C) Q,R
(D) P,R
Ans: (B) Q,S
Q.8- Which of the following statements about thermal wind is NOT correct:
(A) Flow is in geostrophic balance
(B) Horizontal temperature gradient is non-zero
(C) Wind speed varies with height
(D) Flow is quasi-geostrophic
Ans: (D) Flow is quasi-geostrophic
Q.9- A numerical weather forecasting model follows sigma (σ) coordinate system in the vertical. At two locations A and B, the surface pressure is 1000 hPa and 500 hPa respectively. The values of pressure at A and B (in that order) for σ = 0.5 are:
(A) 2000 hPa, 1000 hPa
(B) 500 hPa, 250 hPa
(C) 999.5 hPa, 499.5 hPa
(D) 500 hPa, 0 hPa
Ans: (B) 500 hPa, 250 hPa
Q.10- At a given temperature and pressure, equilibrium vapor pressure over the surface of a rain droplet compared to that over a flat surface of pure water is
(A) Always less
(B) Always more
(C) Always equal
(D) Can be less, equal to or more depending on the size and chemical composition of the cloud condensation nuclei, and droplet radius
Ans: (D) Can be less, equal to or more depending on the size and chemical composition of the cloud condensation nuclei, and droplet radius
Q.11- Velocity field in a geophysical flow is given by u = -5x, v = 4y, w = 0 where u, v, w are zonal, meridional and vertical components of velocity, and x and y refer to eastward and northward distance. Which among the following statements is NOT true for the flow at 45oN:
(A) Flow is incompressible
(B) Relative vorticity is zero
(C) Potential vorticity is positive
(D) Flow is compressible
Ans: (A) Flow is incompressible
Q.12- The distance between Mars and Earth is 0.52 times the distance between Sun and Earth. If the solar constant on Earth is 1370 W m-2, then the solar constant on Mars is __ W m-2. (Round off to one decimal place.)
Ans: 592.8 to 593.2
Q.13- Ideal gas equation for dry air is expressed as p = ρd Rd T, where p is pressure, ρd is density, T is temperature and Rd is gas constant. If CO2 concentration in Earth’s atmosphere quadruples due to fossil fuel burning, then the new gas constant is __ J kg-1 K-1. (Round off to two decimal places.) Take the universal gas constant (R*) = 8.314 J K-1 mole-1, molecular weight of CO2 = 44, and present value of Rd = 287 J kg-1 K-1, present concentration of CO2 = 500 mg kg-1.
Ans: 286.40 287.30
Q.14- On a calm evening under a clear sky, the lowest 20 m of the atmosphere is continuously losing energy at a rate of 10 W m-2 due to radiative cooling. Sensible and latent heat flux exchange with the ground is zero. If air temperature and dew point depression at 6 p.m. are 25oC and 8oC, respectively, the probability of fog formation at midnight is __ %. (Round off to the nearest integer.) Take Cp = 1005 J kg-1 K-1, density of air = 1.15 kg m-3
Ans: 99 to 100
Q.15- The dynamical core of a general circulation model uses 256 spherical harmonic waves to cover the globe in east-west direction. If two grids of the model exactly resolve the shortest of those waves, then the grid spacing at the equator is __ km. (Round off to one decimal place.) Take radius of the earth (RE) = 6400 km.
Ans: 78.4 to 78.6
Q.16- It rains 10 cm in a day over an ocean with a mixed layer depth of 5 m and initial salinity 30 g kg-1. The rain water uniformly mixes with the existing mixed layer water. The final salinity after the rain is __ g kg-1. (Round off to one decimal place.)
Ans: 29.3 to 29.5
Q.17- A moist air parcel is lifted adiabatically to 800 hPa level. Initial temperature and pressure of the parcel are 300 K and 1010 hPa, and the partial pressure of water vapor is 10 hPa. The partial pressure of the water vapor at the new location is __ hPa. (Round off to one decimal place.) Take saturation vapor pressure of water at temperature T as
e_s\left(T\right)=Ae^{-\frac BT}where A = 2.53 × 109 hPa, B = 5420 K, gas constant (R) = 287 J kg-1 K-1, and Cp = 1005 J kg-1 K-1.
Ans: 7.8 to 8.1
Q.18- In steady state, global mean precipitation P is equal to global mean evaporation E from the surface of the earth. If P is 2.8 mm day-1, then global mean surface latent heat flux is __ W m-2. (Round off to the nearest integer). Take latent heat of evaporation of water as 2.5×106 J kg-1.
Ans: 75 to 85
Q.19- A column of seawater from surface to 1000 m depth is initially at rest at the equator. The column is moved to 30oN with no change in column depth. In the absence of friction, the vertical component of relative vorticity of the water in the column at 30oN is __ ×10-5 s-1. (Round off to one decimal place.)
Ans: -7.6 to -7.0
Q.20- Consider two north-south (i.e. meridional) sections A and B in the ocean, separated by 100 km; section B is to the east of section A (as shown in figure below). The steady northward wind stress at A and B are 0.1 N/m2 and 0.2 N/m2, respectively; zonal wind stress is zero everywhere. Density of seawater is 1000 kg m-3. At 30oN, the vertical velocity at the base of the Ekman layer is __ meters per day. (Round off to one decimal place.)
Ans: 1.1 to 1.3
Q.21- A tsunami is a long gravity wave, i.e. its wavelength is much larger than the depth of the ocean. A tsunami moves from point A to point B (see figure below); water depth at A is 2000 m, and water depth at B is 500 m. Assume no frictional losses. By energy conservation, Cg <E>is constant, where Cg is group speed and <E>is the total (potential plus kinetic) energy density of the wave field. If the amplitude of the tsunami at point A is 1 m, its amplitude at B is __ m. (Round off to two decimal places.)
Ans: 1.30 to 1.50
Q.22- At mid-latitudes, long Rossby waves obey the dispersion relation σ = – βk / L-2, where σ is frequency, k is zonal wavenumber, β is rate of change of Coriolis parameter with northward distance (units m-1 s-1), and L is Rossby radius. If L = 100 km, the speed of the long Rossby wave at 45oN is __ m s-1. (Round off to two decimal places.) Take radius of the earth as 6400 km.
Ans: 0.13 to 0.19
END OF THE QUESTION PAPER