Earth Data School
About
Full catalog/M2TUNPQDT
M2TUNPQDT·v5.12.4·dataset

How moisture is changing by altitude, daily cycle (model)

MERRA-2 tavgU_3d_qdt_Np: 3d,diurnal,Time-Averaged,Pressure-Level,Assimilation,Moist Tendencies 0.625 x 0.5 degree V5.12.4 (M2TUNPQDT) at GES DISC
atmosphere NASA GES_DISC Level 4 active
In plain English

What it measures. Tracks how atmospheric moisture — water vapor, cloud liquid, and cloud ice — is gaining or losing at different altitudes, separated by what's driving it, such as air movement versus cloud and rain processes. Averaged by month but kept separate for each part of the day.

How it's made. Comes from MERRA-2, NASA's computer model that merges satellite-era observations into a consistent global picture, gridded across 42 atmospheric pressure levels.

How & where you'd use it. A research input for studying the daily and seasonal behavior of water in the atmosphere; it's a specialist building-block dataset rather than one for casual use.

What's measured

ATMOSPHERE › ATMOSPHERIC WATER VAPOR › WATER VAPOR INDICATORS › HUMIDITY › SPECIFIC HUMIDITYATMOSPHERE › ATMOSPHERIC WATER VAPOR › WATER VAPOR PROCESSES › WATER VAPOR TENDENCYATMOSPHERE › ATMOSPHERIC WATER VAPOR › WATER VAPOR PROCESSES

Coverage & cadence

  • Time span1980-01-01 → ongoing
  • Measured byMERRA-2 (NOT APPLICABLE)
  • Processing levelLevel 4
  • Spatial extent-180, -90, 180, 90
  • StatusACTIVE

What you can do with it

  • Map air pollutants — NO₂, aerosols, ozone
  • Track greenhouse gases and Earth's energy budget
  • Feed weather and air-quality analysis
Official description

M2TUNPQDT (or tavgU_3d_qdt_Np) is a 3-dimensional monthly diurnal means data collection in Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2). This collection consists of assimilations of moist tendencies on the 42 pressure levels, such as tendency of ice (or liquid) water due to dynamics, total ice (or liquid) water tendency due to moist, total specific humidity analysis tendency, and specific humidity tendency due to moist. The information on the pressure levels can be found in the section 4.2 of the MERRA-2 File Specification document. This data collection is the monthly mean of data fields for each 3-hour and time-stamped at the central time starting from 01:30 UTC, e.g.: 01:30, 04:30, … , 22:30 UTC. MERRA-2 is the latest version of global atmospheric reanalysis for the satellite era produced by NASA Global Modeling and Assimilation Office (GMAO) using the Goddard Earth Observing System Model (GEOS) version 5.12.4. The dataset covers the period of 1980-present with the latency of ~3 weeks after the end of a month. Data Reprocessing: Please check “Records of MERRA-2 Data Reprocessing and Service Changes” linked from the “Documentation” tab on this page. Note that a reprocessed data filename is different from the original file. MERRA-2 Mailing List: Sign up to receive information on reprocessing of data, changing of tools and services, as well as data announcements from GMAO. Contact the GES DISC Help Desk (gsfc-dl-help-disc@mail.nasa.gov) to be added to the list. Questions: If you have a question, please read "MERRA-2 File Specification Document", “MERRA-2 Data Access – Quick Start Guide”, and FAQs linked from the ”Documentation” tab on this page. If that does not answer your question, you may post your question to the NASA Earthdata Forum (forum.earthdata.nasa.gov) or email the GES DISC Help Desk (gsfc-dl-help-disc@mail.nasa.gov).

Get the data

m2tunpqdt_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="M2TUNPQDT",
    version="5.12.4",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from GES_DISC
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.