The NCEP Climate Forecast System Reanalysis - NOAA National ...

More documents

Recommendations

Info

1. IntroductionThe first reanalysis at NCEP conducted in the 1990s, resulting in theNCEP/NCAR Reanalysis (Kalnay et al. 1996) or R1 for brevity, would ultimately covermany years, from 1948 to the present (Kistler et al. 2001). It is still being executed atNCEP, to the benefit of countless users for monthly, even daily, updates of the currentstate of the atmosphere. At the same time, other reanalyses were being conducted, namely,ERA15 (Gibson et al. 1997) was executed for a more limited period (1979-1993) at theEuropean Center for Medium Range Forecasting (ECMWF), the Center for Ocean-Land-Atmosphere Studies (COLA) conducted a short reanalysis covering the period May 1982-Nov 1983 (Paolino et al. 1995) and the Goddard Space Flight Center (GSFC/NASA)conducted a reanalysis covering the period 1980-1994 (Schubert et al. 1997). ECMWFhas conducted two subsequent reanalyses, ERA40 (Uppala et al. 2005) and ERA-Interim.The Japan Meteorological Agency (JMA) conducted JRA25 (Onogi et al. 2005), whileGSFC is conducting MERRA (Bosilovich et al. 2008). A 100-year reanalysis using onlysurface pressure data is being conducted at ESRL/NOAA (Compo et al. 2006). Thegeneral purpose of conducting reanalyses is to produce multi-year global state-of-the-artgridded representations of atmospheric states, generated by a constant model and aconstant data assimilation system. To use the same model and data assimilation over avery long period was the great advance during the 1990s, since gridded data setsavailable before 1995 had been created in real time by ever changing models and analysismethods, even by hand analyses prior to about 1965. The hope was that a reanalysis,made after real time, would help in climate studies by eliminating fictitious trends causedby model and data assimilation changes in real time. Although ‘climate’ was theconsideration of overriding importance in justifying the enormous effort involved inconducting a multi-year reanalysis, the techniques used were those of numerical weatherprediction (NWP). This climate–weather linkage lives on to this day. In particular, theanalysis at any given time (t) is the result of a short forecast (the guess field), initialized- 4 -
from a previous analysis (valid at time t-∆t) , amended by assimilating new observationsavailable in a narrow window centered at t. The increment ∆t is by convention 6 hours,but it could, in principle, be shorter or longer. Not surprisingly, most of the laterreanalyses have been executed at operational weather prediction centers, the onlyexception being MERRA (Bosilovich et al 2008) conducted at GFSC/NASA.One very time consuming, but rewarding, part of the first reanalyses was to assemble andconvert older observational data sets into modern formats (such as BUFR), so they couldbe ingested into a modern modeling/data assimilation system. The data mining andpreparation of these data sets is a lasting legacy, and they have been exchanged amongnational and international partners, and used in several more reanalyses (Uppala et al2005; Onogi et al 2005, Bosilovich et al 2008). Every new reanalysis benefits from allprevious reanalyses, and it is likely that mistakes are discovered and corrected to thebenefit of the next user. This truly has been an ongoing activity in the international arena.Errors, big and small, were made in R1. Some were discovered and documented in:http://www.cpc.noaa.gov/products/wesley/reanalysis.html#problem.Kanamitsu et al (2002) executed a corrected version of R1, often called R2, covering onlythe satellite era of 1979-present. Importantly, in spite of correcting many errors andupdating some components of the system, “only minor differences are found between R1and R2 in the primary analysis variables, such as free atmospheric geopotential heightand winds in the Northern Hemisphere extratropics” (Kanatmitsu et al, 2002). Both R1and R2 are being continued at NCEP, an activity sometimes referred to as the ClimateData Assimilation Systems, specifically CDAS1 for R1 and CDAS2 for R2. Running aCDAS implies certain technologies and computer algorithms are frozen in time, which inthe face of ever changing data ingest and computer configurations can be a challenge, andultimately would be impossible. A new reanalysis (ERA-Interim) executed presently atthe ECMWF will be kept up to date (which ERA15 and its successor, ERA40, did not),thereby increasing its utility for real-time applications.- 5 -
Page 2 and 3: ABSTRACTThe NCEP Climate Forecast S
Page 6 and 7: In this paper we only discuss globa
Page 8 and 9: the reanalysis was halted to addres
Page 10 and 11: online archive of data for reanalys
Page 12 and 13: density MESONET data is included in
Page 14 and 15: The 1B datasets were calibrated usi
Page 16 and 17: MetOp is Europe's first polar-orbit
Page 20 and 21: The third GSI feature enabled in th
Page 22 and 23: the hydrostatic assumption. Soon af
Page 24 and 25: esolution with 28 sigma layers in t
Page 26 and 27: SW and LW radiations at one-hour in
Page 28 and 29: SST data. The other uses AVHRR and
Page 30 and 31: y Gent and McWilliams (1990; see al
Page 32 and 33: from the Global Temperature-Salinit
Page 34 and 35: through the end of the data set in
Page 36 and 37: The passive microwave weather filte
Page 39 and 40: from the sea ice/ocean back to the
Page 41 and 42: weight is assigned to the gauge ana
Page 43 and 44: Stream 6: 1 Jan 1994 to 31 Mar 1999
Page 45 and 46: in the mid 1990’s, the period whe
Page 47: e due to a change over the oceans (
Page 52 and 53: In Figure 49, we show the temporal
Page 54 and 55:
distributed in time and space. Desp
Page 56 and 57:
forecast model at a lower resolutio
Page 58 and 59:
Appendix A: AcronymsAER Atmospheric
Page 60 and 61:
ONPCMDIPIRATAPROFLRQBOQuikSCATR1R2R
Page 62 and 63:
TMP2M 2m air temperature 24 / 473TM
Page 64 and 65:
Appendix C: The Data AccessTo addre
Page 66 and 67:
Figure 26 shows the global total bi
Page 68 and 69:
Argo Science Team, 2001: The global
Page 70 and 71:
Compo, G.P., J.S. Whitaker, and P.D
Page 72 and 73:
ozone Mapping and Profiler Suite (O
Page 75 and 76:
Global Forecast System. Manuscript
Page 77 and 78:
and climate models. Atmos. Chem. Ph
Page 79 and 80:
performance Earth system modeling w
Page 81 and 82:
with mesoscale numerical weather pr
Page 83 and 84:
experiments using SSM/I wind speed
Page 85 and 86:
Figure 21: Same as Figure 2, but fo
Page 87 and 88:
Figure 45: The fit of 6-hour foreca
Page 89 and 90:
Figure 1: Diagram illustrating CFSR
Page 91 and 92:
Figure 3: Same as in Figure 2, but
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Figure 15: Radiance instruments on
Page 105 and 106:
Figure 17: Same as in Figure 16, bu
Page 107 and 108:
Figure 19: Global average Tb first
Page 109 and 110:
Figure 21: Same as in Figure 16, bu
Page 111:
Figure 23: Comparisons of the SSU b
Page 114 and 115:
Figure 26: The global total bias fo
Page 116 and 117:
Figure 28: The yearly total of trop
Page 118 and 119:
Figure 30: The vertical structure o
Page 120 and 121:
Figure 32: The global number of tem
Page 122 and 123:
Figure 34: The same as Figure 33, b
Page 124 and 125:
Figure 36: Monthly mean Sea ice ext
Page 126 and 127:
Figure 38: 2-meter volumetric soil
Page 128 and 129:
Figure 40: Schematic of the executi
Page 130 and 131:
Figure 42: Yearly averaged Southern
Page 132 and 133:
Figure 44: Monthly mean hourly surf
Page 134 and 135:
Figure 46: Global mean temperature
Page 136 and 137:
Figure 48: Zonal mean total ozone d
Page 138 and 139:
Figure 50: The subsurface temperatu
Page 140 and 141:
Figure 52: Vertical profiles of the
Page 142 and 143:
Figure 54: Zonal surface velocities
Page 144 and 145:
ProgramPREVENTSACQCACAR_CQCCQCCQCVA
Page 146:
Satellite Starting date Ending Date
show all

The NCEP Climate Forecast System Reanalysis - NOAA National ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?