Print Version: Lesson 11 - Arctic NWP

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Arctic NWP

Arctic NWPSurface Observations

Map showing sounding locations in the Arctic

Locations for routine surface weather observations are in most cases quite widely spaced in the Arctic, primarily due to the lack of major population centers in the region. The end of the cold war caused a dramatic decrease in regular surface observations by the U.S., Canada, and Russia.

Currently, routine soundings are collected from scattered coastal locations throughout the Arctic. Still, the atmosphere over the vast ocean area of the Arctic is largely unmeasured. Unlike lower latitude locations, aircraft ascent/descent profiles are unavailable for almost the entire region.

Arctic NWPSatellite Observations

By far, the largest amount of data over the Arctic comes from the polar-orbiting satellite system. These satellites provide approximately 14 nearly-polar orbits each day, offering excellent spatial and temporal coverage. Operated by the U.S. and Europe, the system currently includes six spacecraft platforms containing both radiometers and microwave sounders. The radiometers provide estimates of cloud cover and sea surface temperature. Microwave sounders provide estimates of tropospheric and stratospheric temperature and water vapor. Together these instruments provide a wealth of data, but have limited capabilities for accurate low-level observations, particularly in the presence of clouds.

Arctic NWPModels

The lack of surface observations as input means that the analyses used to create the initial conditions for weather models are not robust. All global forecast models include the Arctic in their domains, but the data paucity at high latitudes means that the model predictions have only limited usefulness. Issues with model performance include predicting the locations of high amplitude ridges and troughs as well as resolving radiation fluxes and turbulence in the boundary layer. Arctic clouds—particularly stratus—are notoriously difficult to forecast or simulate in current weather prediction models.

Global models include the NCEP GFS and its ensembles, the Canadian GEM model and its ensembles, ECMWF models and their ensembles, UKMET, GSM, and NOGAPS.

Dedicated polar models include the polar version of the MM5 (PSU/NCAR Fifth-generation Mesoscale Model), which is used for both synoptic and climate studies. This model has been shown to perform well in comparisons with observations over Greenland, though a slight moist bias is seen near the surface. A polar version of WRF (Weather Research & Forecasting Model) also exists and has been tested over the Arctic and AntArctic. Both these models are run routinely only for operations in Antarctica.

Arctic NWPQuestions

Question 1

The majority of Arctic observational data in NWP models comes from which of the following sources? (Choose the best answer.)

The correct answer is b) "Satellites."

There are very few land-based observing stations in the Arctic, and even fewer that launch weather balloons to collect soundings.

Question 2

[True/False] Dedicated mesoscale models are routinely run for the Arctic Domain.

The correct answer is False.

Mesoscale models, like the MM5 or WRF, are run routinely for AntArctica, but not for the Arctic.

Arctic NWPReferences

Serreze, M. C. and R. G. Barry, The Arctic Climate System, Cambridge University Press, 2005.