DB1504T4004-2024农业气候年景评估方法

1504Assessmentmethodforagriculturalannualclimaticstatus 本文件按照GB/T1.1—2020《标准化工作导则第1部分：标准化文件的结构和起草规则》的规定农业气候年景评估方法GB/T20481-2017气象干旱气象要素年景annualmeteorologicalele气象灾害年景annualmeteorologicaldis农业气候年景agricultureannualclimati4农业气候年景评估方法4.1气象要素年景评估方法4.1.1要素选取4.1.2计算方法后进行加权累加，得到气象要素年景指数Ime。气象要素年景指数按公式（1）计算：Ime——气象要素年景指数；Is——日照年景指数。4.2气象灾害年景评估方法4.2.1灾害选取4.2.2计算方法后进行加权累加，得到气象灾害年景指数Imd。气象灾害年景指数按公式（2）计算：Imd=A×Idr+B×Irs+C×Ifr····················································Imd——气象灾害年景指数；Idr——干旱年景指数；B——权重系数，取值0.35；Irs——暴雨年景指数；Ifr——霜冻年景指数。4.3农业气候年景评估方法利用标准化（方法见附录B）后的气象要素年景指数Ime和气象灾害年景指数Imd加权累加，得到农业气候年景指数ICS。农业气候年景指数按公式（3）计算：ICS=A×Ime+B×Imd················································ICS——农业气候年景指数；Ime——气象要素年景指数；Imd——气象灾害年景指数。4.4农业气候年景等级确定ICS≤P10P10＜ICS≤P30P30＜ICS≤P70P70＜ICS≤P90P90<ICSA.1气温年景指数气温年景指数（仅计算对农业生产有影响的生长季期间，即4-9月，降水年景指数和日照年景指数/N········································Ti,j——为第j站第i旬平均气温，单位为摄氏度(℃);-,——为第j站第i旬平均气温的气候平均值，单位为摄氏度(℃);σi,j——为第j站第i旬平均气温的标准差；N——区域内参加统计的国家基准、基本气象观测站数。Ip=[Σ=1Σ10|(SPI30)i,j|]/N································(SPI30)i,j——为第j站第i旬末的30天标准化降水指数,按照GB/T20481-2017中附录D计算；N——区域内参加统计的国家基准、基本气象观测站数。/N········································Si,j——为第j站第i旬平均日照，单位为小时（hσi,j——为第j站第i旬平均日照的标准差；N——区域内参加统计的国家基准、基本气象观测站数。标准差、标准化及百分位计算方法·····························2··········································Yi——第i个样本值；···························l(p)=(1-y)xj+yx(j+1)·························································(B.4)y=p×n+-j································································(B.6)l(p)——第i个分位数；x——升序排列后样本序列；j——第j个序列数。确定单站日干旱异常值Iddr（表C.1）。累加当月区域内所有站点的逐日干旱异常值，得到月干旱异常值Imdr，具体计算见公式（C.1）。Imdr=Imdr——月干旱异常值；N——区域内参加统计的国家基准、基本气象观测站数；Iddr,i,j——第i天第j站的日干旱异常值。12345MCIMCI≤-2.0的月干旱异常系数wmdr（表C.2）。表C.2不同百分位（P）与月干旱异常12345加权累加当年生长季内（4-9月）逐月干旱异常值与该月干旱异常系数的乘积，权重系数为当月平均雨量与年平均雨量的比值，得到干旱年景指数Idr，计Idr=Σ=4Imdr,m×wmdr,m×Rm···················································Idr——干旱年景指数；Imdr,m——第m月干旱异常值；wmdr,m——第m月干旱异常系数；Rm——第m月月平均雨量与年平均雨量的比值。暴雨年景及等级的确定根据日降水量来计算，日降水量≥50mm定义为暴雨日（日降水量指前一日对某一单站，暴雨异常值Ri按公式（C.3）RA,i=···································RA,i——第i站平均暴雨量，单位为毫米（mmRM,i——第i站各暴雨日中的最大暴雨量，单位为毫米（mmRs,i——第i站总暴雨量，单位为毫米（mm）。累加当年区域内所有国家基准、基本气象观测站年暴雨异常值，即得到区域年度暴雨异常暴雨年景指数Irs，按公式（C.5）计算。Irs=Σ1Ri······································································Irs——暴雨年景指数；N——区域内参加统计的国家基准、基本气象Ri——第i站暴雨异常值。初霜日为夏末秋初气象站地面最低温度（T）小于或等于0℃的第一日，终霜日为春末夏初气象站霜冻灾害等级划分应符合表C.3及表C.4根据初、终霜冻灾害等级，参照表C.5确定初霜冻异常值FS和终霜冻异常值FE。0123Fi=Fsi+FEi··········································Fi——第i站霜冻灾害异常值；Fsi——第i站初霜冻灾害异常值；FEi——第i站终霜冻灾害异常值。···································Ifr——霜冻年景指数；N——区域内参加统计的国家基准