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

More documents

Recommendations

Info

CFSR-Lite for the TOVS period, but dramatically better in the ATOVS period, asuggestion that the higher resolution CFSR and GFS assimilation systems are exploitinginformation in the ATOVS systems not available from TOVS. Note that the NH and SHCFSR and GFS scores at the end of the period are nearly comparable, an indication thatthe medium range skill of the prediction of synoptic scale features is now comparableover oceans and continents.9.2 Atmospheric MassMonitoring atmospheric mass as part of a reanalysis effort is now common, seeFig. 10 in Uppala et al (2005) and Fig. 1 in Trenberth and Smith(2005), which comparedtraces of surface pressure, precipitable water and dry pressure in ERA40, ERA15 and R1.Compared to previous reanalyses, the new CFSR is very well behaved in terms of theatmospheric mass or, very nearly equivalent, the surface pressure. One sanity check is tostudy the time variation of the ‘dry pressure’, which should almost always be conserved.The dry component of surface pressure is defined locally by subtracting the precipitablewater (in all its forms) from the total surface pressure, converted to pressure units. Indeed,the global mean of dry pressure is almost constant, with a standard deviation of 0.10 hPaaround its mean value of 983.01 hPa over the 1979-present period (not shown). Theglobal mean of the total pressure varies somewhat more, a standard deviation of 0.16 hPaaround its mean of 985.39 hPa, since the water content of the atmosphere is free to vary.However, even this variation is less than 1 hPa from maximum to minimum in the globalmean. In earlier reanalyses (Trenberth and Smith 2005), these variations were muchlarger and a consistency between total pressure and precipitable water was lacking.The mass balance of the atmospheric water component, with its input byevaporation (E) and output by precipitation (P), remains somewhat worrisome even in theCFSR. Global average monthly mean precipitation (P), evaporation (E) and E-P areshown in Figure 43. The global mean P is always larger than E (by a non-negligible fewtenths of a mm/day) and this imbalance grows around 1998, probably related to the ingestof new data systems, like AMSU. The decrease of global mean E-P after 1998 appears to- 46 -
e due to a change over the oceans (Figure. 43 b and c) and results from both an increasein precipitation (Figure. 43a) and a decrease in evaporation (Figure. 43b). Anotherfeature is an increase in the amplitude of the seasonal cycle of E-P over land, after 1999(Figure. 43c, blue curve), which appears to be due to a weaker seasonal amplitude inprecipitation (Figure. 43a). Further analyses are required to investigate the causes ofthese features in the CFSR. Assimilation of observations could, in principle, violate thegoverning equations, and the hydrological imbalance in the CFSR is one prominentexample of this violation.9.3 Atmospheric TidesWe now discuss the 2D atmospheric mass distribution in some detail here, namely theatmospheric thermal (solar radiation induced) tides in the CFSR. The previous reanalyseshave had many types of users. Among them, geodesists and oceanographers (Ponte andRay 2002; Ray and Ponte 2003; Velicogna et al 2001; de Viron et al 1999), who requireglobal atmospheric surface pressure, especially atmospheric tides, for their research andreal-time applications. Compared to R1, the new CFSR offers several very significantadvances for such users. First, and perhaps foremost, is the availability of hourly output.Figure 44 gives an example of the solar tides as analyzed by CFSR for March 1998 (anarbitrarily picked month). The 24 global maps in one figure give a compact display of thetides. Each map is obtained from data available on the model T382 Gaussian grid. In thered (blue) areas, the pressure is higher (lower) than the daily mean. Units are hPa. Timestarts in the upper left (00Z) corner, then proceeds down to 3Z, continues at the top of thenext column to 4Z and so on, to the end of the diurnal cycle at 23Z. The data at 0, 6, 12and 18 Z are from the actual analysis made at these times, while the data in between thesecycles is from the coupled guess forecast. One can clearly see the red and blue areaspropagate westward around the earth in one day. A cross-section along the equator showsa dominant wave number two pattern, corresponding to the semi-diurnal solar oscillation.This type of map is available for each month from 1979-present, at the CFSR website at:http://cfs.ncep.noaa.gov/cfsreanl- 47 -
Page 2 and 3: ABSTRACTThe NCEP Climate Forecast S
Page 4 and 5: 1. IntroductionThe first reanalysis
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: in the mid 1990’s, the period whe
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 97 and 98:
Figure 9: Same as in Figure 2, but
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 ...

Create successful ePaper yourself

Delete template?

Save as template?